Symposium BM1 : Spatiotemporally and Morphologically-Controlled Biomaterials for Medical Applications

The innovative engineering methodologies that allow for the preparation of functional polymer materials by simple strategies have significant fundamental interest and enormous potential to address unmet clinical needs. This talk will focus on the design principle that is simple, novel and applicable, for the development of polymeric materials for distinct applications. In treating three pulmonary diseases, two degradable nanoparticle systems based on one functional polyphosphoester will be discussed, with the highlight of the simple, efficient and versatile chemistry involved in each stage of the production. For the prolonged gastric retention with improved safety profile, the development of three polymer systems will be presented, giving the emphasis to a novel pH-responsive supramolecular gel that helped to achieve a 5-7 days gastric retention in a large animal model promising the application to solve the poor medication adherence.

Drug-eluting material systems have proven useful in a variety of clinical settings, including preventing restenosis with stenting, treating cancer and enhancing wound healing. These systems benefit from tunable drug release kinetics, continuous drug release, and local delivery, which together provide spatiotemporal control over drug availability and diminish drug toxicity. I will describe our efforts to overcome one major hurdle to widespread use of drug-eluting systems in vivo – that they carry a finite depot of drug and require invasive procedures to refill. I will describe a technology to modify materials so as to capture blood-circulating drug refills, allowing for repeated refilling of the depots for local release. Bioorthogonal chemistry and nucleic acid-based methods for selective depot replenishment will be discussed. Repeated drug refilling and release improved outcomes in cancer models and allowed for selective drug homing in models of lower limb ischemia and osteomyelitis. Refillable drug delivery devices that enable repeated and spatiotemporally controlled drug release may have clinical applications in cancer therapy, wound healing, immunotherapy, and drug-eluting vascular grafts and stents.

New biosensors, entirely made of biodegradable materials and designed for being implanted in the human body, are currently emerging. These sensors open the field for new therapeutic applications, without need for a second surgery to remove the devices after their predefined period of use. The development of new spatiotemporally-controlled biomaterials is required for being used in such sensors.
In the present work, we investigate the use of the biodegradable elastomer POMaC in a new stretchable strain and pressure sensor developed in the context of tendons recovery monitoring. This biomaterial is used both as a key structural and packaging material. Various synthesis approaches, combining exposure to UV irradiation (photocrosslinked POMaC) and oven curing (polycondensation crosslinked POMaC), are evaluated. The material response to long-term mechanical cycling before and after in vitro degradation in PBS solution is also investigated. We show in particular that the tensile modulus and resistance to cycling of POMaC can be adjusted using an appropriate synthesis approach, to better fit the final therapeutic application. Moreover, a strategy for the final packaging of the sensor based on sealing with UV-exposed prePOMaC is investigated. We show efficient packaging properties, with negligible sensor signal variation after hours of immersion in PBS solution.
Our investigations on the synthesis and assembly of this biodegradable elastomer permit the development of a sensor with high sensitivity, fast response time and long-term stability, allowing its use in the context of tendon tissues recovery monitoring.

Despite the rise of 3D printing of thermoplastics both in industry and the general public, a key limitation preventing the widespread use of cell-based 3D printing is the lack of suitable bio-inks that are cell-compatible and have the required properties for printing. Current commonly used biomaterials have distinct limitations when used as a bio-ink including difficulty maintaining a homogeneous cell suspension, avoiding cell damage during extrusion, customizing the printed matrix properties to facilitate cell-matrix interactions, and printing within a bath to prevent cell dehydration while preserving high print resolution. We designed a new family of tunable biomaterials specifically designed for cell-based 3D printing. These hydrogel-based bio-inks are produced from a blend of engineered recombinant proteins and peptide-modified, alginate polysaccharides. The use of engineered proteins provides control of ligand presentation for cellular attachment and signaling, while the alginate enables cyto-compatible, rapid crosslinking within a hydrated sample. This design is advantageous due to the ability of the bio-ink to undergo two-stages of crosslinking: (i) weak, peptide-based, self-assembly to homogeneously encapsulate cells within the ink cartridge, to prevent cell settling in the print cartridge, and to mechanically shield the cells from damaging forces during extrusion and (ii) electrostatic crosslinking of alginate upon printing within a calcium bath to rapidly stabilize the construct and to tailor the final mechanical properties for optimal cell-matrix interactions with full cell hydration.

Enzymatic transformation is essential mechanism for signal transduction in the cell. In this work, we report the use of enzyme to regulate the peptide folding and self-assembly, thus induced the supramolecular hydrogelation. HPLC and LC-MS analysis identify that the designed phosphopeptide is the substrate of protein phosphatase. Circular dichroism (CD) spectra show the enzyme is able to modulate the rate of peptide folding and self-assembly. Electron microscopy reveals that the enzymatic reaction converts the unfolding peptide to protofibrils, and nanofibrils. Rheology confirmed the formation of stable hydrogel. As the first case of enzyme-triggered peptide folding and self-assembly, this work not only provide an approach to generate sophisticated materials, but also offer insight how to modulate the interaction of peptide and cellular environment.

Hydrogels are attractive as cell carriers and bioinks in injection-based therapies and 3D bioprinting as they can protect cells from damaging shear forces during the injection or the additive manufacturing process. Hydrogels can also offer extracellular matrix mimicking environments for both tissue engineering applications and 3D cell culture. Different applications and processing conditions require hydrogels with significantly different properties. To this end, we have established a flexible modular strategy for fabrication of supramolecular hydrogels that offer means to tightly control both the self-assembly process as well as the mechanical and structural properties of the hydrogels. A set of different modular peptide-polymer hybrids have been synthesized using de novo designed peptides that dimerize and fold into well-defined alpha-helical motifs.^[1,2] The peptides were grafted to four-arm PEGs and hyaluronic acid using click chemistry. Self-assembly of physical hydrogels was triggered by peptide dimerization and folding. The properties of the hydrogels can be rationally and dynamically modulated using peptides with different affinities for dimerization and by complexation of cations. In addition to offer means to dynamically assemble and disassemble the hydrogels, the storage modulus of the hydrogels can be varied from about 200 to 1000 Pa when using peptides with affinities for dimerization spanning from the nanomolar to the picomolar range.^[3] This novel strategy thus enables fabrication of dynamic stimuli-responsive soft materials for biomedical applications with properties that can be programmed using defined and tunable peptide-mediated interactions.


[1] D. Aili, F.-I. Tai, K. Enander, L. Baltzer, B. Liedberg, “Self-assembling fibers and nano-rings from disulphide linked helix-loop-helix polypeptides”, Angew. Chem., Int. Ed., 2008, 47, 5554-5556.

[2] C. Aronsson, S. Dånmark, F. Zhou, P. Öberg, K. Enander, H. Su, D. Aili, "Self-Sorting Heterodimeric Coiled Coil Peptides with Defined and Tuneable Self-Assembly Properties”, Sci. Rep., 2015, 5, 14063; doi:10.1038/srep14063.

[3] S. Dånmark, C. Aronsson, D. Aili, "Tailoring Supramolecular Peptide-Poly(ethylene glycol) Hydrogels by Coiled Coil Self-Assembly and Self-Sorting", Biomacromolecules, 2016, 17, 2260–2267.

The ability to create three-dimensional (3D) biomaterial structures with high resolution and aspect-ratio enables significant biomedical applications. Numerous methods including 3D printing technologies have been developed to fabricate microdevices and particles with well-defined 3D structure. However, these techniques are limited in terms of shape, aspect ratio, scalability, and either require potentially toxic additives or lack the fine resolution demanded for some applications. Here we present a novel method - termed StampEd Assembly of polymer Layers (SEAL) - which can create versatile 3D microstructures of pure biodegradable polymers such as poly-lactic-glycolid acid (PLGA), and use this method to create a robust drug delivery platform with unique pulsatile release kinetics. SEAL combines computer-chip manufacturing technologies, micromolding, and a novel layer-by-layer assembly process to fabricate 3D microstructures of biomedically relevant materials without processing additives. We employed SEAL to create PLGA/drug core-shell microparticles for controlled drug delivery applications. These SEAL-fabricated particles exhibited delayed, pulsatile release for up to 2 months, which is particularly exciting to the development of single-injection vaccines. We also demonstrate the use of SEAL for creating particles using an enteric polymer that exhibits pH-dependent release following oral administration for selective colon targeting. Finally, we show that the SEAL method is compatible with sensitive biomacromolecules such as the highly instable inactivated polio vaccine (IPV). As such, SEAL is a powerful method that can supplement 3D printing when high resolution, high-throughput, and biocompatibility are required for proper device function. We anticipate many applications from this platform technology such as the creation of 3D tissue synthetic scaffolds with well-defined microstructure and injectable drug delivery devices with unique targeting or release kinetics based on complex 3D architecture and/or material composition.

Functionalized nanoparticles (NPs) are versatile materials with heterogeneous surface properties that can be engineered to mimic typical biological macromolecules. Recently, a particular class of charged, amphiphilic NPs were shown to embed within lipid bilayers to obtain configurations similar to transmembrane proteins. Embedding involves the dynamic rearrangement of NP surface properties to adapt to the bilayer environment. This behavior is surprising, however, because the NPs must also transport charged groups across the hydrophobic bilayer core within short timescales to stably insert into the bilayer. Here, we use atomistic molecular dynamic simulations to gain a mechanistic understanding of this rapid charge transport. We show that charged species grafted to a bilayer-embedded scaffold – such as the NPs or multispanning transmembrane proteins – translocate across the bilayer more rapidly than isolated ions. We further study the system features that affect translocation rates in order to identify methods to facilitate the translocation of specific charged groups. This work suggests design guidelines for synthetic materials capable of transporting charged, soluble small molecules across bilayers, which may be useful for ferrying therapeutic molecules to the interior of cells for drug delivery applications.

Robotics deals with automated machines that can locomote themselves and operate tasks in various environments over many orders of magnitudes in scale. One of the most inspiring goals is the construction of smart and powerful nanorobotic systems for operation in the human body. However, viscous forces dominate inertial forces at such small scales, leading to the “low-Reynolds number challenge” for nanoscale propulsion. This presentation will discuss newly created multi-functional nanorobots which can overcome this challenge by utilizing local chemical reactions to achieve efficient movement in biological matrices. With selectively engineered materials, the nanorobots possess numerous attractive properties, including biocompatibility, biodegradability, high loading capacity, and the ability to autonomously release of payloads ‘on-the-fly’. The increased capabilities and sophistication of these tiny robots hold considerable promise for a variety of biomedical applications ranging from drug delivery to minimally invasive surgery. Particularly, using zinc-based micromotors as model robots, we reported the first in vivo study of artificial micromotors in a living organism. Such in vivo evaluation examines the distribution, retention, cargo delivery, and acute toxicity profile of synthetic motors in mouse stomachs via oral administration. We demonstrate that the acid-driven propulsion in the stomach effectively enhances the binding and retention of the motors as well as of cargo payloads on the stomach wall.
In another design, we demonstrate an enteric micromotor system capable of precise positioning and controllable retention in desired segments of the Gastrointestinal (GI) tract. These motors, consisting of magnesium-based tubular micromotors coated with an enteric polymer layer, act as a robust nanobiotechnology tool for site-specific GI delivery. The micromotors can deliver payload to particular location via dissolution of their enteric coating to activate their propulsion at the target site towards localized tissue penetration and retention. Our work is anticipated to significantly advance the emerging field of biomedical nanorobots and to open the door to in vivo evaluation and clinical applications of these biomedical nanorobots.

Ref:
[1] Artificial Micromotors in the Mouse’s Stomach: A Step toward in Vivo Use of Synthetic Motors. ACS Nano, 2015, 9, 117–123.
[2] An Enteric Micromotor can Selectively Position and Spontaneously Propel in the Gastrointestinal Tract. Submitted to Nature Mater.

Sepsis is the most common cause of death in hospitalised patients, with an annual incidence of 1 million cases and 200,000 deaths in the USA alone¹. Moreover, approximately 25% of sepsis cases are complicated by the development of Acute Respiratory Distress Syndrome (ARDS), which also incurs a high mortality rate². Both sepsis and ARDS are characterised by excessive pro-inflammatory responses, for which there are currently no effective treatments. Instead, supportive therapy within the critical care setting forms the mainstay of treatment and so novel therapeutic strategies are urgently required.

Given the fundamental role of sialic acid-binding immunoglobulin-like lectins (Siglecs) in modulating immune responses, these receptors represent potential anti-inflammatory targets in sepsis and ARDS. In particular, previous studies demonstrated that engagement of murine Siglec-E negatively regulates Toll-like receptor (TLR)-mediated inflammation³. In this current work, a novel sialylated nanoparticle was developed to actively target Siglec receptors expressed on macrophages, with potential therapeutic utility in sepsis and ARDS.

Polylactic-co-glycolic acid (PLGA) nanoparticles were formulated via a salting-out approach and decorated with α2,8 N-acetylneuraminic acid targeting moieties (α2,8 NANA-NP). Physicochemical characterisation of α2,8 NANA-NP revealed an average diameter of 152 ± 13 nm and a polydispersity index of 0.16 ± 0.08, indicative of a monodisperse size distribution. When tested in cultures of lipopolysaccharide (LPS)-stimulated murine macrophages, α2,8 NANA-NP potently inhibited the secretion of pro-inflammatory tumour necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) cytokines in a Siglec-E dependent manner. Therapeutic efficacy was also confirmed in both systemic and pulmonary in vivo models of inflammation, where α2,8 NANA-NP enhanced survival rates, attenuated neutrophil infiltration, inhibited pro-inflammatory cytokine production and augmented anti-inflammatory IL-10 levels, amongst other readouts. Mechanistic studies uncovered that the functionality of α2,8 NANA-NP was both macrophage- and IL-10-dependent, given the loss of efficacy in clodronate-treated and IL-10 knockout mice, respectively. Moreover, the translational potential of this nanoplatform was demonstrated in cultures of primary human monocytes and macrophages, and also in a human ex vivo lung perfusion model, where α2,8 NANA-NP significantly attenuated LPS-induced inflammation.

Collectively, these findings demonstrate that the targeted cross-linking and activation of Siglecs can be exploited therapeutically in models of sepsis and ARDS. In addition to these syndromes, α2,8 NANA-NP may also find potential application in other conditions underpinned by aberrant pro-inflammatory signalling.

¹ Immunity 2014, 40(4), 463-75
² Intensive Care Med 2004, 30(1), 51-61
³ J Immunol 2009, 183(12), 7703-9

Inorganic nanocrystals with unique optical, electronic, magnetic, and structural properties have found widespread use in biosensing, bioimaging, surface-enhanced spectroscopy, drug delivery, and catalysis. Organization of the nanocrystals into superstructures often leads to collective properties that are different from those in the discrete units. Controlled assembly of the nanocrystals is currently under intense research and development for a wide range of applications in electronic devices, biosensing, and drug delivery. This talk summarizes our recent results in developing plasmonic and magnetic superstructures for cancer diagnostic and therapeutic applications. Metallic nanostructures with localized surface plasmon resonance arising from the collective excitation of conduction electrons LSPR spectral shifts induced by interparticle plasmonic coupling have attracted considerable research interest in controlled assembly of plasmonic nanoparticles, which, in conjugation with responsive “smart” coatings, has been exploited to detect a wide range of molecular targets and environmental factors. We have developed versatile approaches to engineer nanoparticle surface with polymer ligands and assemble the nanoparticles into well-defined structures in aqueous dispersion and at oil-water interfaces, which hold great promise in traceable drug delivery, surface enhanced Raman scattering, and biosensing. We have developed a new approach, built upon the use of mussel-inspired polydopamine, to preparing robust multifunctional nanochains of magnetic nanoparticles with readily tailorable surface chemistry for applications in different environments. We have found that the resulting rigid magnetic nanochains undertake localized rotation when placed in a spinning magnetic field, making it possible for the nanochains to serve as nanomotors and nanoscale stir bars to promote molecular transport and mixing in extremely small spaces, which is highly desirable for applications in microreactors and ultrasmall sensing devices. More interestingly, conjugation of DNA aptamer ligands of specific receptors overexpressed on cancer cell membrane led to targeted nanochains that bound to selective cancer cells, and subsequent exposure to a spinning magnetic field caused pronounced cell death via magnetolysis of cell membranes.

Therapeutic delivery of proteins and nucleic acids is a difficult goal. Of the many challenges in the delivery process, perhaps the most demanding is providing these biologics with access to the cytosol. Most delivery strategies employ endosomal uptake, requiring endosomal escape for the payload biologics to be effective. In our research, we have developed an alternative strategy that uses nanoparticle-stabilized nanocapsules (NPSCs) to deliver proteins and nucleic acids (siRNA and DNA) directly to the cytosol. These NPSCs use a membrane fusion process to bypass the endosomal pathway, providing highly effective payload delivery. The direct access to the cytosol makes NPSCs effective tools for therapeutic delivery, particularly in conjunction with intracellular targeting. Mechanistic studies of NPSCs and their use in vivo for immunomodulation will be discussed.

In the currently ongoing outbreak, zika (ZIKV) is co-circulating with dengue virus (DENV) and chikungunya (CHKV), which also share the same vector, the mosquitoes Aedes aegypti and Aedes albopictus. Infection by any of the three diseases leads to similar flu-like symptoms, complicating proper disease management. Point-of-care diagnostics are critically needed for rapid response in patient treatment, resource allocation and to predict epidemics. Lateral flow devices are ideal candidates to diagnose diseases in remote areas because they can be operated by non-experts, are cheap, portable, and do not require electric power to be operated. We present results on a machine-readable multiplexed lateral flow device for the detection of several tropical disease markers. By making the device readable by a mobile phone, it is able to provide real-time epidemiologic data to monitor disease distribution. The device relies on a lateral flow immunoassay, which uses capillary flow and the accumulation of ligand-coated nanoparticles to detect the presence of target proteins. Gold nanoparticle-antibody conjugates are critical to ensure that the device will have enough sensitivity to detect the illness even at low concentrations of target protein, such as in early stages of the disease. The sensitivity of lateral flow devices greatly depends on the nature of the ligand-target pair and their binding thermodynamics on the nanoparticle interface. We engineer the nanoparticle shape, size, surface chemistry, and biofunctionalization in order to lower the overall detection limit of the device. The nanoparticle surface properties and biofunctionalization are characterized by gel electrophoresis, DLS, and fluorescence/optical spectroscopy in conjunction with chemical displacement.
These new, effective, low-cost devices would be very useful in developing countries, but also for developed countries, where they can contribute to lowering the overall cost of healthcare and enable widespread use for other applications such as crowdsourcing.

Glioblastoma multiforme (GBM) is a devastating disease with extremely poor survival statistics owing to high rates of disease recurrence. Typical treatment of patients diagnosed with GBM is surgical resection of accessible tumorous tissue followed by radiotherapy and chemotherapy. Chemotherapeutic choices are limited on account of most drugs’ poor propensity to cross the blood brain barrier. Systemic treatment with unspecified concentrations of chemotherapy is ineffective and risks adverse side effects. An alternative approach involves the use of supramolecular hydrogels, which can be readily loaded with therapeutic agents for sustained localized delivery.

High water content (99%) and biocompatible hydrogels based on hyaluronic acid (HA) backbones developed within the our group rely on non-covalent cross-links between polymers, formed by utilizing the dynamic host-guest chemistry of cucurbit[8]uril (CB[8]). In this system, amino acid derived “guest moieties” that are bound to HA polymers complex in a 2:1 fashion with a “host-molecule” CB[8], creating multiple cross-links resulting in gelation. As these complexes are non-covalent they can be broken with mechanical stress and instantly reformed upon relaxation due to fast binding kinetics. This material can encapsulate water-soluble drug compounds, be injected through a needle and rapidly self heal preventing any cargo loss. Tissue strength and elasticity can also be replicated in the hydrogel properties by simply modulating the polymer or CB[8] concentration.

In vitro release studies of various drug compounds encapsulated in the hydrogel have been performed and efficacy against multiple patient-derived human GBM cell lines determined. In vivo experiments with a mouse model are currently underway. We envisage that access to such drug-delivery technology will lead to clinical studies in the near future with an overall goal to prevent disease recurrence and improve patient survival rates.

Mitochondria are vital organelles to eukaryotic cells. Since damage and dysfunction of mitochondria cause cell apoptosis, mitochondrial specific targeting gains lots of interest in cancer therapeutics. Delivery of cancer specific drug into mitochondria has already been established in recent years by various approaches such as conjugation of drug molecule with mitochondria targeting ligands. However, mitochondrial damage due to self-assembly of amphiphilic molecules inside mitochondria still remains challenging. It is already well proved that peptides have intrinsic ability to form various self-assembled structure such as fiber, ribbon, sphere and vesicle. Study of selfassembling behavior of peptide inside the live cell organelle is least established till now. Here, we introduce mitochondria targeting short peptide containing sequence as Py-FFK(TPP) [Py = Pyrenebutyric acid, TPP = Triphenyl phosphonium, F = phenyl alanine, K = lysine]. The TPP moiety can provide mitochondrial specific targeting to mitochondria and pyrene butyric acid provides both a self-assembling building block and a fluorescent probe. The peptide exhibited well-defined morphology in water, high mitochondrial localization and cancer-cell cytotoxicity. The improved mitochondrial localization of peptide is attributed to the TPP moiety and high hydrophobicity. Under the mitochondrial environment the peptide can undergo aggregation due to increased concentration above the critial aggregation cocnetraion (40 uM). The self-assembly of the peptide induces mitochondrial stress and thereby generates ROS and causes cell death.

A surface that can suppress nonspecific binding and resist biofouling is critical for the performance of biomedical and analytical devices. A number of bio-inert chemical functions has been identified using self-assembled monolayers (SAM). Significant effort has been made to apply these chemistries in the development of biomedical products; however, a durable and easy to use bio-inert coating is still lacking. We developed coating formulations for the treatment of various surfaces to reduce protein binding and cell adhesion. We demonstrated that the bio-inert coating is stable under gamma irradiation and the treated plastic surface strongly resists adhesion of various cells including 3T3, MCF-7 and MDA-MB-231.

This presentation will cover several recent advances in the development of light- and inflammation-responsive polymers as tools for biological research and drug delivery. In the area of light-responsive materials, four exciting strategies will be discussed: chemically amplifying the light signal to accelerate degradation, single-photon absorption of red light, novel upconverting structures enabling efficient conversion of more biologically compatible wavelengths, and application of previously reported polymers to the treatment of various diseases. The chemical amplification strategy relies on phototriggered unmasking of acidic groups that hydrolyze adjacent ketals, which overcomes ketals’ requirement of low pH for efficient degradation. Particles composed of the photocaged-acid/ ketal polymer degrade rapidly upon brief irradiation. The red light-degradable polymer incorporates a photocage not previously used in responsive materials, which cleaves in hydrophobic environments (unlike coumarins). Particles composed of this polymer, when subcutaneously injected and irradiated through tissue, release sufficient drug to significantly reduce carrageenan-induced paw inflammation in mice. Finally, we have evidence that a UV-degradable polymer (Fomina et al., J Am Chem Soc 2010) may be useful for the delivery of anti-angiogenics in the eye to treat macular degeneration. This strategy would preserve clinician control over dose timing while reducing the frequency of intravitreal injections. UV-degradable particles are stable in the eye for months and release a therapeutically effective dose of a small molecule anti-angiogenic; the irradiation required for release is well-tolerated by the eye.
Inflammation-responsive materials have been recently applied in the lab towards prevention of systemic inflammatory response syndrome (SIRS), treatment of Age Related Macular Degeneration with a single annual injection of a drug depot of VEGF Trap and detection of atherosclerotic plaque likely to disrupt and cause a heart attack or stroke. The first project involves delivering anti-inflammatory drugs in nanoparticles composed of our polythioether ketal (published in 2011). Using this strategy to deliver drugs 12 h prior to the bacterial toxin LPS reduces mortality in mice, suggesting that such nanoparticles could lead to a means of preventing organ failure following systemic infection or trauma. In the second, particles composed of dextran modified to be acid- and H₂O₂-responsive encapsulate Gd-based nanocrystals with unprecedented relaxivity, such that MRI signal is silenced until encountering inflammation, where particles loosen and nanocrystals can relax surrounding water molecules. This material’s ability to detect inflammation in vivo has been demonstrated using fluorescence activation;

Porphyrins are aromatic, organic, light-absorbing molecules that occur abundantly in nature, especially in the form of molecular self-assemblies. In 2011, we first discovered ‘porphysomes’, the self-assembled porphyrin-lipid nanoparticles with intrinsic multimodal photonic properties. The high-density porphyrin packing in bilayers enables the absorption and conversion of light energy to heat with extremely high efficiency, making them ideal candidates for photothermal therapy and photoacoustic imaging. Upon nanostructure dissociation, fluorescence and photodynamic activity of porphyrin monomers are restored. In addition, metal ions can be directly incorporated into the porphyrin building blocks of the preformed porphysomes thus unlocking their potential for PET and MRI. By changing the way porphyrin-lipid assembles, we developed HDL-like porphyrin nanoparticles (<20nm), porphyrin microbubbles (~2um), giant porphyrin vesicle (~100um) and hybrid porphyrin-gold nanoparticles, expanding the purview of porphyrin nanophotonics. By mimicking light harvest systems in photosynthetic bacteria, we introduced high-ordered porphyrin aggregates into supramolecular assemblies, resulting unprecedented photonic properties (e.g., reversible photoacoustic nanosensors). Such optical properties are also responsible for our discovery of the ultrasound-induced microbubbles-to-nanoparticle conversion phenomenon, which may open the door to bypass the enhanced permeability and retention effect when delivering drugs to tumors. By closing the nano-micro-nano loop, the simple yet intrinsic multimodal nature of porphyrin self-assembly represents a new frontier in cancer imaging and therapy.

Drug carriers have traditionally been spherical and designed to be more difficult to clear by using synthetic polymers that are hydrophilic such as PEG. We have explored filamentous shapes and also 'Self' signaling by peptides rather than PEG in various efforts to advance delivery science. In the first example (1), we sought to improve the delivery of aromatic drugs using micelles, particularly elongated filomicelles, and to that end aromatic groups were integrated into the hydrophobic block of a degradable di-block copolymer. These aromatic filomicelles were formed by self-directed assembly of amphiphilic di-block copolymer PEG-PBCL with suitable block ratios. Long and flexible worm-like micelles with an aromatic core were loaded with a common chemotherapeutic, Paclitaxel, for tests of release as well as effects on cancer cell lines in vitro and in vivo. For carcinoma lines in vitro and initial tests in vivo, flexible filomicelles with an aromatic core form an efficient drug delivery system that leads to higher cell death than previously reported systems, while inducing aneuploidy in surviving cells. In the second example, we explore better biomimickry with a 'Self' polypeptide. ‘Self’ cells are spared due to a polypeptide found on all cells that marks cells as ‘Self’, limiting their phagocytic clearance in vitro and in vivo – even when displayed on nanoparticles (2). Application to nanoparticle-based tumor imaging will be illustrated, as will application of the pathway to a cell-based therapy for cancer that exploits the ability of phagocytic cells to deeply penetrate into disease sites such as tumors.

(1) P.R. Nair, K. S. Anbazhagan, K.R. Spinler, M.R. Vakili A. Lavasanifar, and D.E. Discher. Filomicelles from aromatic di-block copolymers increase paclitaxel-induced tumor cell death and aneuploidy compared to aliphatic copolymer. Nanomedicine (May/June 2016).
(2) Rodriguez, P.L.; Harada, T.; Christian, D.A.; Pantano, D.A.; Tsai, R.K.; and Discher, D.E. Minimal 'Self' peptides that inhibit phagocytic clearance and enhance delivery of nanoparticles. Science 2013 339: 971-975

Molecules or materials that can undergo property changes upon stimulation by a specific biological target promise a myriad of biomedical applications. We have been interested in a molecular ligand scaffold that can undergo in situ assembly, ideally even in the complex in vivo settings, after the activation by a specific molecular target. This assembling process would transform small ligands to large molecular complexes even nanoparticles at the target-presenting location. We envision that such systems can then be applied to in vivo imaging of the target activity and drug delivery. There are many reported examples of these small ligand assemblies, however, few could take place in vivo. This presentation will introduce our effort in developing such a molecular ligand scaffold for in vivo molecular imaging. We call it Target-Enabled in Situ Ligand Assembly (TESLA).

Our TESLA platform is based on a biocompatible chemical condensation reaction between two chemical groups -- 1,2-aminothiol and 2-cyanobenzothiazole. TESLA ligands possess both groups and upon the activation by the target, TESLA ligands will chemically condense, followed by assembly and formation of nanoparticles. Several TESLA ligands have been designed to validate the strategy in vitro, in living cells under the control of pH, disulfide reduction and/or enzymatic cleavage. Importantly, this TESLA platform is also working in living animals, and I will describe examples of TESLA probes in image treatment-induced apoptosis in tumor cells in vivo with whole-body fluorescence imaging, positron emission tomography (PET), and magnetic resonance imaging (MRI). We expect more TESLA probes may be designed to image many molecular targets and enable medical applications beyond imaging.

Biology offers an endless variety of functional solutions to motion, sensing, and control. This talk will summarize parts of a program focused on biomimetic and biostimulated soft actuators.

It remains a huge scientific challenge to understand and mimic the utilisation of chemical energy in
biological systems to achieve the highly adaptable organisation and sophisticated functions like
active transport, motility, self-repair, replication, and adaptability. The development of biomimetic
systems with similar energy consuming organisation and functions requires a radical departure
from equilibrium self-assembly approaches, towards out-of-equilibrium systems driven by the
continuous input of energy.
In our research we focus on the development of active materials driven by chemicals fuels. First, I
will discuss how active materials can result from the transient self-assembly of synthetic molecules,
driven by the consumption of a chemical fuel. In these materials, reaction rates and fuel levels,
instead of equilibrium composition, determine properties such as lifetime, stiffness, and selfregeneration
capability. Then, I will discuss our recent steps to achieve temporal and spatial over
fuel-driven self-assembly by the development of a chemical reaction network that allow for
feedback control. Such systems will form the basis for self-organising systems and for design and
construction of energy-consuming dynamic devices and materials.
References:
[1] J. Boekhoven, A.M. Brizard, K.N. Kowlgi, G.J. Koper, R. Eelkema, J.H. van Esch, Angew. Chem. Int. Ed. 2010, 49
DOI: 10.1002/anie.201001511.
[2] J. Boekhoven, W. Hendriksen, G. Koper, R. Eelkema, J.H. van Esch, Science 2015, 349, 1075.
[3] A.G.L. Olive, N. Hakimin Abdullah, I. Ziemecka, E. Mendes, R. Eelkema, J.H. van Esch, Angew. Chem. Int. Ed. 2014,
53, DOI:10.1002/anie.201310776.

Molecular designs that afford tunable supramolecular assemblies are of interest in a variety of applications, including drug delivery, sensing, and diagnostics. When these assemblies are nanoscopic in size and are responsive to specific stimulus, then the interests in these nanoscale scaffolds are even higher. We have developed amphiphilic supramolecular assemblies featuring these characteristics. In addition, these assemblies also can bind guest molecules efficiently and release them in response to specific triggers. Our utlimate goal is to develop design algorithms that lend themselves to predictably design nanoscale assembleis that respond to physical, chemical, or biological stimuli. Fundamental and translational implications of these findings would be numerous. We will report our progress in this area.

Nanomedicine has offered new solutions for cancer diagnosis and therapy. However, the survival improvement offered by current nanomedicines remains modest. To further advance the development of nanomedicines, it is crucial to investigate and understand the correlation between the properties of nanomedicines (e.g., particle size) and biological responses to lay the foundation for the design of next-generation nanomedicines with optimum efficacy against cancers. Here, we report the development of size-controlled, monodisperse drug-silica nanoconjugates and systematically evaluation of their size effect on antitumor efficacy in both primary and metastatic tumor models. We find that the 50-nm nanoconjugate has the most optimal antitumor efficacy compared to 200- and 20-nm nanoconjugates. The silica-drug nanoconjugates show great potential for clinical applications because of their long-term biocompatibility and their capability of in vivo clearance. I will also present our recent progress of developing polymeric nanoparticles for cancer treatment.

Nanoparticles find intriguing applications in drug delivery. The morphological properties of nanoparticles can greatly impact their ability to cross biological barriers such as cell membranes, intestinal epithelium, blood brain barrier and vascular endothelium. Several recent studies, including our own, have outlined the role of particle morphology in their transport across these barriers and these studies have shown that particle morphology can indeed significantly alter their transport. In many cases, morphology operates in synergy with other parameters such as size and surface chemistry to bring out unique interplay between these key parameters. My talk will present an overview of the current understanding of the role of particle morphology in crossing these varied barriers and lessons learned about the similarity and differences in the role of particle morphology in determining delivery across the barriers.

Nature has developed a fascinating strategy of cryptobiosis (“secret life”) for counteracting the stressful, and often lethal, environmental conditions that fluctuate sporadically over time. For example, certain bacteria sporulate to transform from a metabolically active, vegetative state to an ametabolic endospore state. The bacterial endospores, encased within tough biomolecular shells, withstand the extremes of harmful stressors, such as radiation, desiccation, and malnutrition, for extended periods of time and return to a vegetative state by breaking their protective shells apart when their environment becomes hospitable for living. Certain ciliates and even higher organisms, e.g., tardigrades, and others are also found to adopt a cryptobiotic strategy for their survival. A common feature of cryptobiosis is the structural presence of tough sheaths on cellular structures. However, most cells and cellular assemblies are not “spore-forming” and vulnerable to the outside threats. In particular, mammalian cells, enclosed with labile lipid bilayers, are highly susceptible to in vitro conditions in the laboratory and daily-life settings, making manipulation and preservation difficult outside of specialized conditions. The instability of living cells has been a main bottleneck to the advanced development of cell-based applications, such as cell therapy and cell-based sensors.

Recent studies have sought to chemically control and tailor the metabolic behaviors of non-spore-forming cells, as well as enhancing their viability against adverse environmental conditions, by forming thin (< 100 nm), tough artificial shells. These living “cell-in-shell” structures, called artificial spores (chemically-formed spore-like structures), enable control of cell division, protection against physical and chemical stresses, and cell-surface functionalizability, as well as providing the cells with exogenous properties that are not innate to the cells but are introduced chemically, such as magnetism, heat-tolerance, and UV-resistance. In addition, recent developments in the field have further advanced the synthetic tools available to the stage of chemical sporulation and germination of mammalian cells, where cytoprotective shells are formed on labile mammalian cells and broken apart on demand. Based on these demonstrations, the (degradable) cell-in-shell hybrids are anticipated to find their applications in various biomedical and bionanotechnological areas, such as cytotherapeutics, high-throughput screening, sensors, and biocatalysis, as well as providing a versatile research platform for single-cell biology.

The use of alternating layer-by-layer (LbL) assembly enables a modular platform that can control release of therapeutics over a broad range of time scales, from several seconds to multiple months. We have developed systems that can address a range of different wound healing needs by taking advantage of this tunable platform and the ability to incorporate drugs programmed to release at a range of different rates and with staged release behavior. The nature of the layering process enables the incorporation of different drugs within different regions of the thin film architecture; the result is an ability to uniquely tailor both the independent release profiles of different therapeutics from the same film, and the order of release of molecules to targeted regions of the body.
This approach can be used to assemble thrombin protein and self-assembling peptides in a dry film conformal coating on a fully resorbable sponge to engage rapid hemostasis over a period of seconds to minutes; these systems can be stored for extended time periods in medical facilities, thus allowing rapid deployment by medical staff and a means of introducing more effective hemostasis for cases of internal bleeding and hemorrhage. The addition of the co-release of anti-infective agents such as vancomycin to these systems adds additional value to the soldier by preventing infection across a broad spectrum, which is particularly relevant on the battlefield. On the other hand, staging of release of multiple growth factor proteins can achieve the regeneration of collagen and remodeling of tissue in wounds at appropriate time points to facilitate wound closure and tissue vascularization. Moreover, multilayered release coatings as thin as a half micron to several microns can be designed to deliver different growth factor proteins or siRNA and other biologic drugs directly to wounds to correct the dysregulation of wound healing processes that have gone awry, from burn and scar tissue to the closure of chronic wounds such as diabetic ulcers.

Subunit vaccines are well-defined at molecular level and have been widely developed in modern vaccine industry due to their good safety, great ease of manufacture and storage. However, compared with live vaccines, their immunogenicity is poor, particularly for the CD8⁺ T-cell responses. Subunit vaccines and adjuvants have therefore been formulated into nanomaterials to raise immune responses, but only few of them can elicit CD8⁺ T-cell responses. More importantly, the antigens and adjuvants are needed to be covalently conjugated or simultaneously formulated into the same nano-carrier, which makes their production in large scale more challenging. We had developed an injectable supramolecular hydrogel of a self-assembling D-tetrapeptide as a very promising adjuvant to raise both humoral and cellular immune responses. Antigens including OVA and attenuated tumor cells can be simply incorporated within the hydrogel by vortex or gentle shaking before injections. We found that the resulting hydrogels with physically entrapped antigens are extremely potent vaccines that can significantly stimulate CD8⁺ T-cell response and remarkably inhibited tumor growth. Our hydrogel should enable a wide range of subunit vaccines and make the manufacture of modern vaccines much easier.

Reference:
Zichao Luo, Qinjie Wu, Chengbiao Yang, Huaimin Wang, Tao He, Hao Chen, Xingyi Li,* Changyang Gong*, Zhimou Yang* A powerful CD8⁺ T-cell stimulating D-tetra-peptide hydrogel as a very promising vaccine adjuvant, Adv. Mater. Under Revision.
Huaimin Wang，Zichao Luo，Youzhi Wang，Tao He，Chengbiao Yang，Chunhua Ren，Linsha Ma，Changyang Gong*，Xingyi Li*，Zhimou Yang*，Enzyme-catalyzed Formation of Supramolecular Hydrogels as Promising Vaccine Adjuvants，Adv. Funct. Mater., 2016, 26(11): 1822-1829.
Yue Tian, Huaimin Wang, Ye Liu, Lina Mao, Wenwen Chen, Zhening Zhu, Wenwen Liu, Wenfu Zheng, Yuyun Zhao, Deling Kong, Zhimou Yang*, Wei Zhang, Yiming Shao*, Xingyu Jiang*, A Peptide-based Nanofibrous Hydrogel as a Promising DNA Nanovector for Optimizing the Efficacy of HIV Vaccine, Nano Lett., 2014, 14(3): 1439-1445.

Three-dimensionally porous scaffolds are indispensable for tissue engineering and regenerative medicine as they provide physical supports and adjustable microenvironments for cells to attach, stretch, migrate, proliferate, and differentiate. An ideal scaffold should possess certain properties such as appropriate pore size, porosity, and interconnectivity, among others. To this end, porous scaffolds with an inverse opal structure emerged. Unlike other scaffolds that are fabricated by stochastic porogen methods with random structures, an inverse opal scaffold is characterized by uniform and well-controlled pores and interconnecting windows, in addition to their highly reproducible structure among different batches of production. In this talk, I will start with a biref discussion of the motivation for developing the inverse opal scaffolds and an introduction to the fabrication method. I will then highlight the advantages of using such porous scaffolds over their counterparts with non-uniform structures through side-by-side comparisons. Finally, I will discuss a few examples on the unique applications of the inverse opal scaffolds in regenerative medicine and offer some perspectives on the future directions.

Self-sorting event is ubiquitous in living systemrs and it should be one of the crucial factors for their dynamic and flexible functions. Therefore, it is recently considered that self-sorted supramolecular assemblies such as supramolecular nanofibers are invaluable for complex but well-organized systems with sophisticated functions like living cells. To design and control the self-sorting events in synthetic materials, understanding their structures and dynamics in detail is indispensable. I herein describe in situ real-time imaging of self-sorted supramolecular nanofibers consisting of a peptide gelator and an amphiphilic phosphate gelator by using confocal laser scanning microscopy and super resolution imaging. Design and selection of orthogonal supramolecular fibers and appropriate fluorescent probes allowed us to visualize the self-sorted fibers entangled in 2D and 3D in the hydrogel state with 80 nm resolution. In situ time-lapse imaging unveiled that the physicochemical properties remained intact in the orthogonal fibers and that there is a remarkable difference in the fiber formation rate between the two fibers. Moreover, we are able to directly visualize the stochastic non-synchronous fiber formation with the cooperative mechanism in real-time, which cannot be detected by conventional techniques. I would also like to discuss the function of supramolecular hydrogels made of such self-sorted fibers.

Reconstructive, cardiac, vascular, and transplant surgeries rely heavily on the anastomosis of venous and arterial vessels. However, traditional suturing techniques have an increased rate of failure as the size of the vessels decrease. Millimeter-sized vessels are difficult even for experienced surgeons and anastomosing micron-sized vessels is barely possible with conventional microsurgical techniques. Herein, we report the design of a peptide-based hydrogel capable of undergoing multiple consecutive phase transitions enabling its use as an injectable temporary intraluminal stent during micron-scale anastomosis. The peptide (APC1) undergoes an initial sol-gel phase transition under physiological conditions to form a self-supporting hydrogel directly in a syringe. The resultant gel demonstrates shear-thin/recovery rheological properties that allow its syringe delivery directly into the lumen of collapsed vessels re- establishing their shape and providing mechanical support. The transparent gel can also be applied to the interspace between vessel ends, providing a flexible medium into which the vessels can be inserted, physically manipulated, but temporally fixed after placement, allowing clamp-free approximation with minimal lumina handling. Suturing is performed directly through the shear-thinning gel medium. On completion, gel applied external to the vessel is washed away. The final gel- from the vessel interior is enabled by the incorporation of a photo-caged amino acid, 4-methoxy-7-nitroindolinyl glutamic acid [E(MNI)], into the primary peptide sequence. Irradiation of the material with 365 nm light de-cages the residue and disrupts the hydrogel network allowing the resumption of blood flow. Biophysical and in-vivo experiments show that this responsive hydrogel has the potential to decrease the surgical difficulty associated with anastomosing ultra-small vessels, adding a new tool to the armamentarium for micro- and supermicrosurgical procedures.

Supramolecular assemblies, biopolymers, and proteins found in extracellular matrices and in the cytosol control many functions of the cell in a highly dynamic fashion. The assemblies commonly take the form of supramolecular polymers formed by protein monomers. Another important family of biopolymers includes charged polysaccharides with complex and aperiodic sequences that can bind many proteins. The highly dynamic structures serve as scaffolds for biological signals and mediators of fundamental processes such as cell division and migration. This lecture will describe the development of a novel synthetic platform of materials that enables the temporal switching of signals presented to cells in order to control their behavior. The new biomaterials are constructed with DNA and peptide nucleic acids conjugated to peptides. Using these systems we have observed reversible migration of neural stem cells and also reversible biological attachment of cells to substrates. A second platform to be described in this lecture involves the use of glycopeptide filaments with capacity for multipotent activation of signaling proteins. The lecture will discuss the importance of these two emerging platforms in regenerative medicine.

The tremendous functionality of living systems is based on sequence-specific polymers and it is increasingly clear that much simpler oligomers, such as peptides, are suitable building blocks for supramolecular nanomaterials with myriad applications. However, the design and selection of self-assembling sequences is challenging due to the vast combinatorial space available. In this take, we will present our recently developed methodology that enables the peptide sequence space to be searched for self-assembling structures. In this approach, unprotected homo- and hetero dipeptides including aromatic, aliphatic, polar and charged amino acids are subjected to continuous enzymatic condensation, hydrolysis and sequence exchange to create a dynamic combinatorial peptide library. The free energy change associated with the assembly process itself giving rise to selective amplification of self-assembling candidates. By changing the environmental conditions during the selection process, different sequences and consequent nanoscale morphologies are selected. Thus, dynamic peptide libraries enable directed discovery of peptide nanomaterials under user-defined conditions. Applications in discovery of theranostic peptide nanoparticles for cancer therapeutics will be discussed.

Biomimetic, three-dimensional cell culture opens the opportunity to both improve our understanding of disease progression and achieve more predictive drug screening. We have designed a series of crosslinked hydrogels based on hyaluronan, a naturally occurring polysaccharide that makes up the extracellular matrix of cells throughout the body. Hyaluronan is upregulated in breast and other cancers and is often a marker for breast cancer, making it an excellent biomaterial in which to design other key biomimetic properties. To gain greater insight into the factors that influence cell migration in breast and brain cancer, we have designed Diels-Alder crosslinked hyaluronan hydrogels where mechanical and chemical properties are independently controlled, thereby providing insight into why some of the key factors of the extracellular matrix that influences cell migration. Since glioblastoma is an invasive cancer and breast cancer cells migrate to other sites, the role of the extracellular matrix and other cell types on these biological phenomena can help us understand disease progression. To gain greater insight into cell fate when exposed chemotherapeutic drugs, we have synthesized aldehyde-crosslinked hyaluronan hydrogels where the chemistry allows the cells to be cultured in a 3D environment. Here the cellular response to chemotherapeutic drugs can be explored and compared to those observed when cells are cultured in 2D or in the standard Matrigel. A key advantage of the these hyaluronan-based hydrogels is their well-defined chemistry and reproducibility, a key limiting affect of Matrigel.

Low-molecular-weight hydrogels have attracted attention as a functional soft material for a variety of applications (tissue engineering, DDS carriers and cell cultivation). The low-molecular-weight gelators can be designed to self-assemble in response to various stimuli owing to their variability of the molecular structures. In particular, enzyme-responsive low-molecular-weight gelators have high potential in the biochemical and medical applications. Here we report a peptide-lipid low-molecular-weight gelator designed to transform from a gelator precursor to a gelator by a cancer-related enzyme. The transformation was mediated by a proteolytic enzyme, matrix metalloproteinase-7 (MMP-7) that was secreted by cancer cells, resulting in the gelation. We anticipated that the gelation by a low-molecular-weight gelator inside or around cancer cells would affect the low-molecular-weight gelator of cancer cells. In the present study, we succeeded in the uptake of the low-molecular-weight gelator and also in the gelation of cytoplasm of cancer cells, inducing the selective death of cancer cells based on the intracellular self-assembly of our low-molecular-weight gelator.
The gelator precursor consisted of three moieties, a low-molecular-weight gelator, an enzyme-cleavage site and a gelation-preventing moiety. The properties of the gelator precursor were evaluated by transmission electron microscopy, gelation test and HPLC analysis. These investigations revealed that the hydrolysis of the gelator precursor by MMP-7 produced the gelator molecules, which self-assembled to form entangled nanofibres, resulting in the gelation of an aqueous phase.
To investigate the cytotoxicity of the gelator precursor, the gelator precursor was added to cultures of the mammalian cells. The gelator precursor had cytotoxicity to HeLa cells (cancer cells) but not to normal cells. The cytotoxicity was correlated with the amount of MMPs secreted by cells.
To explore the mechanism of the cancer-cell death, a gelator analogue containing a fluorophore was added to the cell culture with the gelator precursor. The fluorescence microscope observation revealed the cell uptake of the gelator and the low fluidity of the cell interior, suggesting the gel-like structure inside a cell. This study proposes that the molecular self-assembly inside cancer cells can be available as a novel strategy for developing a novel anti-cancer drug.

Functional luminescent nanoparticles are promising materials for in vitro and in vivo optical imaging and therapy due to their unique optical and chemical properties. In this talk, I will present two new types of biocompatible luminescence nanoparticles. The first type of materials is upconversion nanoparticles (UCNPs). They absorb low energy near-infrared (NIR) light and emit high-energy shorter wavelength photons. Their special features allow them to overcome various problems associated with conventional imaging probe at both single molecule and ensemble levels. I will present new developments regarding engineering UCNPs towards deep tissue imaging, photodynamic therapy, optogenetic applications in neuroscience and immunotherapy. The second type of nanoparticles is persistent luminescence nanoparticles (PLNPs). They are bioluminescence-like and possess unprecedented in vivo deep tissue energy rechargeability, outstanding signal-to-noise-ratio with no need for an excitation resource (light) during imaging, and they can be directly detected with existing imaging systems. These nanoparticles continue to emit light for minutes or hours and, in some cases, days, after turning off the excitation source. These long-lasting, light-emitting nanocrystals can provide noninvasive imaging technology for evaluating structural and functional biological processes in living animals and patients.

Nucleic acids are generally regarded as the payload molecule in gene therapy, requiring a carrier for intracellular delivery. Given the recent discovery that spherical nucleic acids enter cells rapidly compared to their linear counterpart, however, nucleic acids also have the potential to function as a delivery vehicle. We report a strategy where the nucleic acid component acts as both a payload for intracellular gene regulation and the delivery vehicle for the drug component. A bioreductively activated, self-immolative disulfide linker is used to tether the drug, allowing free drug to be released upon cell uptake. We found that the DNA-drug nanostructures enter cells ca. 100 times faster than free DNA, exhibit increased stability against nuclease, and show nearly identical cytotoxicity as free drug toward cancer cells. These DNA-drug nanostructures allow one to separately access a gene target and a drug target using only the payloads themselves, bypassing the need for a complex co-carrier system.

Cancer is the second leading cause of death in the United States, next only to heart disease. More effective diagnostic and therapeutic strategies are in urgent need for better management of patients with cancers. Both inorganic and organic (or polymeric) nanoparticles (NPs) have been widely explored for therapeutic and diagnostic applications. Among others, inorganic NPs are attractive for the treatment, diagnosis, and detection of tumors, because of their unique features as compared with their organic and polymeric counterparts. For example, the surface plasmonic resonance and photothermal effect of Au NPs leverage their functions in simultaneous cancer imaging such as photothermal and photoacoustic imaging, as well as photothermal ablation of tumors. The response of magnetic NPs to magnetic fields enables their contrast-enhanced magnetic resonance imaging (MR) imaging and targeted delivery of therapeutic agents. For this purpose, single NPs are often used and functionalized with organic or polymeric ligands to improve their stability, biocompatibility and functionality.
While single NPs are attractive, the self-assembly of NPs can yield materials with new or advanced properties that are different from their individuals. For example, the organization of Au NPs allows for tuning the absorption of NP ensembles in the near-infrared (NIR) window which is highly desired for in vivo applications. The clustering of magnetic NPs within micelles dramatically increases the MR imaging contrast and responsiveness to external magnetic field. It is, therefore, expected that the ability to design assembled structures with tailored spatial arrangement of NPs may facilitate the utilization of inorganic NPs in biomedical applications. In this talk, I will present our efforts to develop new strategies for the self-assembly of polymer-functionalized inorganic NPs into functional hybrid materials and to evaluate the hybrid assemblies for cancer imaging and treatment. Specifically, I will introduce i) the molecular or atomic mimicking assembly of gold and magnetic NPs into a diverse range of complex nanoarchitectures; and ii) the utilization of hybrid assemblies, particularly vesicular structures containing gold NPs, magnetic NPs or both for effective multimodality cancer imaging (i.e., photothermal, photoacoustic, and MR imaging) and combinational cancer therapy (i.e., photothermal ablation of tumor, photodynamic therapy, and targeted delivery-based chemotherapy).

3D printing is a promising approach for designer biomaterial architectures with information-rich structure and dynamic functionality. In particular, stimuli-responsive hydrogels consisting of crosslinked, hydrophilic polymers could be used for tissue engineering, drug delivery and other biomedical applications. One design consideration is that these biomaterials must be responsive to at least two physicochemical stimuli – the first to pattern desired structures and additional orthogonal stimuli to trigger dynamic behaviors such as degradation. Here, we show reversible 3D printing of alginate hydrogel microstructures using stereolithography (SLA) and subsequent degradation using ion chelation. Alginate is crosslinked by divalent cations, which can be generated by selective illumination of photoacid generators (PAG) in the presence of insoluble salts with these cations. We systematically explore how hydrogel degradation kinetics, pattern fidelity and mechanical properties depend on the concentration and composition of divalent cations in the precursor solution. We use degradable 3D printed alginate structures as “obstacle courses” to investigate collective epithelial migration in confined geometries. We envision other applications in 3D biofabrication of soft robots, organs on chips and other bioinspired microdevices.

Hydrogels are an important class of biomaterial that have received much attention for tissue engineering and controlled drug-delivery applications on account of their similarity to soft biological tissue and highly tunable mechanical properties. Supramolecular hydrogels are dynamically cross-linked polymer networks exhibiting viscous flow under shear stress (shear-thinning) and rapid recovery of mechanical properties when the applied stress is relaxed (self-healing). These properties afford minimally invasive implantation in vivo though direct injection or catheter delivery to tissues, contributing to a rapid gain in interest in their application for drug delivery and tissue engineering. Herein, we discuss the preparation and application of shear-thinning, injectable hydrogels driven by non-covalent interactions between modified biopolymers (BPs) and biodegradable nanoparticles (NPs) comprised of poly(ethylene glycol)-block-poly(lactic acid) (PEG-b-PLA). Owing to the non-covalent interactions between PEG-b-PLA NPs and BPs, the hydrogels flow under applied stress and their mechanical properties recover completely within seconds when the stress is relaxed, demonstrating the shear-thinning and injectable nature of the material. Moreover, the hierarchical construction of these biphasic hydrogels allows for multiple therapeutic compounds to be entrapped simultaneously and delivered with differential release profiles in vitro and in vivo. Delivery of the loaded therapeutics is controlled both by Fickian diffusion from the hydrogel and erosion-based release from the gel surface and can be tuned over several months, enabling novel long-term treatment strategies for chronic diseases. Furthermore, their mild formation and unique flow properties allow for facile encapsulation and implantation of thereapeutically-relevant cells with enhanced viability and retention within the implantation site. Overall, this presentation will demonstrate the facile synthesis of an injectable hydrogel affording minimally invasive application in vivo and controlled release of therapeutics and therapeutic cells.

Multiple sclerosis (MS) and other autoimmune diseases occur when the immune system incorrectly attacks self-molecules. In MS, for example, the immune system attacks myelin – a matrix that insulates neurons in the brain. The effects of this attack are devastating, degrading patient motor function until even simple tasks are impossible. Current treatments for autoimmunity are not curative and leave patients immunocompromised. For these reasons, new experimental therapies seek tolerance against specific self-antigens, without the broad suppression of current treatments. Responses toward self-antigens are generated in lymph nodes and the spleen, with the development of inflammation or tolerance influenced by the concentration and form of antigen reaching these sites. In particular, recent studies show that the configuration in which antigens are presented in lymph nodes can alter the processing of these ligands to activate natural regulatory pathways involved in tolerance. Thus efficient delivery of self-antigen to LNs with uniform, tunable control over peptide morphology or display density could enable more specific and effective therapies for autoimmune diseases. Toward this goal, we used simulation and experimental measurements to design nanocrystalline semiconductor quantum dots (QDs) that display dense arrangements of myelin self-peptides associated with disease in MS. These peptide-QD conjugates are uniform in size (<20 nm) and enable tunable display of 10-150 peptides per QD. In cell culture, this configurability allows direct control over the level of expansion of myelin-reactive T cells, while in mice, the conjugates are rapidly concentrated in draining lymph nodes; the intrinsic fluorescence of the QDs allows direct visualization of this process without addition of other components or fluorescent labels. During a pre-clinical mouse model of MS, treatment with peptide-QDs reduced disease incidence 10-fold and eliminated paralysis in mice. Strikingly, the degree of tolerance – and the underlying expansion of regulatory T cells measured in these mice – correlated with the density of myelin molecules installed and presented by the QDs. This is the first time QDs have been used to induce tolerance, creating new opportunities to study and combat autoimmunity by simultaneously controlling the display of peptide ligands in lymph node or other immunological tissues, while visualizing the trafficking and processing of these conjugates.

Macroporous natural dynamic materials (DM) were extracted from date palm (Phoenix dactylifera L.) and coated by natural polymers composite (carboxymethyl cellulose, polyvinyl alcohol and crosslinked by ethyleneglycol diglycidylether). The polymer coated bioinspired dynamic materials (PDM) were used in in-vitro investigations of controlled delivery of albandazol. DM, PDM and drugs loaded capsules (PDM-ALB) were characterized by scanning electron microscope (SEM), surface area (BET), Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The length of DM was found to be 20-20.5 mm and the pore sized was between 50-135 nm, as measured using SEM. The studies revealed that maximum loading of the drug is at pH 6.0 (97.2%, with 50 mg/ml,). The results indicate that by increasing the pH from 1.4 to 7.4, the cumulative release rates of albandazol in physiological buffer solution (PBS) is more than two times as in simulated gastric fluid (SGF). In addition, the in-vitro toxicity against Caco-2 cells was tested by the 3-[4,5-dimethylthiazole-2-yl]-2,5 diphenyltetrazolium bromide (MTT) assay, and the results showed that PDM are biocompatible materials. The overall results encourage continuing studies on the clinical use of PDM as drug carriers.
Keywords: Terpolymer, FTIR, activation energy, antimicrobial activity, metal complexes.

In recent years there have been significant technological advances in the development of applications and electronic devices, on the other hand, there have been significant research in various areas such as medicine, optics, physics, chemistry, electronics, etc. Together both approaches, both scientific and technological, have converged in the development of new techniques for medical diagnosis. These new medical diagnostic techniques based on the use of the properties of light and the interaction of the same with biological samples are known as optical biopsy or, optical methods for non-invasive medical diagnosis. In particular, there are non-invasive analytical sciences to biomedical research in optical techniques. Which provide detailed information on the molecular composition, structure and interaction of the relationship between diseases and biochemical changes. One of the techniques most used today is Raman spectroscopy, which provides a "fingerprint" of the molecular structure of the sample that can be used to identify the material being analyzed.

However a disadvantage is that small amounts of clinically significant substances in biological samples beyond the detection limit of conventional Raman spectrometers, making them difficult or impossible to detect. Due to this low intensity in the Raman signal for biological samples, a variety of agents have been manufactured metal nanoparticles with unique optical properties for diagnostic and medical treatment. To perform Raman amplification of this signal, it is necessary to implement the technique known as surface enhanced Raman spectroscopy (SERS). Hydroquinone is a molecule of great interest because it is a substance found in skin lightening creams, which, when applied in high concentrations, it can be the cause of skin cancer. By means of Raman spectroscopy, a qualitative analysis for subsequent medical diagnosis is made.

The combination of an environment-sensitive fluorophore, 4-nitro-2,1,3-benzoxadiazole (NBD), and peptides have yielded supramolecular nanofibers with enhanced cellular uptake, brighter fluorescence, and significant fluorescence responses to external stimuli. We had designed and synthesized NBD-FFYEEGGH that can form supramolecular nanofibers and emit brighter than its counterpart of NBD-EEGGH without the self-assembling property. The nanofibers of NBD-FFYEEGGH could specifically bind to Cu²⁺, leading to the formation of fluorescence quenched elongated nanofibers. This fluorescence quenching property was enhanced in self-assembling nanofibers and could be applied for detection of Cu²⁺ in vitro and within cells. In a further step, an enzyme-cleavable DEVD peptide was placed between NBD-FFY and the copper binding tripeptide GGH. The resulting self-assembling peptide NBD-FFFDEVDGGH also showed strong fluorescence quenching to Cu 2+. Upon the enzymatic cleavage to remove the Cu²⁺-binding GGH tripeptide from the peptide, the fluorescence was restored. The cellular uptake of nanofibers was better than that of free molecules because of endocytosis. The supramolecular nanofibers with fluorescence turn-on property could therefore be applied for detection of caspase-3 activity in vitro and within cells. We believe that the combination of environment-sensitive fluorescence and fast responses of supramolecular nanostructures would lead to a useful platform to detect many important analytes.
Moreover,we had reported optimized ratiometric fluorescent probes by peptide self-assembly.The resulting self-assembled nanoprobes show extraordinary stability in aqueous solutions and extremely low background fluorescence in buffer solutions. Our optimized probes with much bigger ratiometric fluorescence ratios also show an enhanced cellular uptake, lower background noise, and much brighter fluorescence signal in the cell experiment. Our study provides a versatile and very useful strategy to design and produce fluorescent probes with better performance.

Stimuli-responsive hydrogels have been used for chemical and biological sensing. Depending on the chemical side groups and moieties available on the hydrogel framework, the hydrogel undergoes a volume change in response to the presence of target stimuli, such as solution pH, temperature, and target biomolecules. The volume change of the hydrogel-based sensor is typically transduced into optical signals, including reflectance from hydrogel thin films, resonance spectra of hydrogel photonic crystals or direct measurement of volume change in microscope. The lack of direct electrical readout limits its utility for sensor applications. In this paper, we experimentally demonstrate the use of a carbon nanotube (CNT)-hydrogel composite as a biosensor that allows for transduction of the volume change to the change of its electrical conductance upon the binding of target molecules.
A neutravidin (nAv)-responsive conductive hydrogel was developed to demonstrate the detection of target nAv proteins by measuring the electrical conductance of the hydrogel. The high electrical conductivity and high aspect ratio of CNTs make them suitable for forming electrically conductive composite with adjustable functionalities. However, it is extremely difficult to process hydrophobic CNTs in water or hydrophilic hydrogel prepolymer mixtures without forming any aggregated CNT clusters. The issue was mitigated by applying carboxymethyl cellulose (CMC) polymer to serve as a mediator to improve the dispersion of CNT in hydrogel prepolymer solutions. The bioresponsive hydrogel was formed by thermal curing of a prepolymer mixture consisting of two parts – (1) bioresponsive hydrogel frameworks composed of acrylamide (AAm), cross-linker methylene bis-acrylamide (mbisAAm) and succinylated biotin (biotin-NHS), and (2) conductive polymer solution formed by CNT/CMC mixture. To facilitate electrical characterization and sensor device integration, the hybrid composite thin film (< 10 µm) was patterned and cured on interdigitated gold electrodes. Current-voltage measurements under various PBS buffer concentrations and solutions with pH ranging from 2 - 11 suggest that the conductance of the hybrid hydrogel is almost independent of ionic strength and pH level. The former results from the large CNT density in hydrogel whereas the latter pH independency can be attributed to the fact that the pKa’s of AAm (4.7) and CMC (4.5) are very close such that the hydrogel remains ionized throughout the pH range. The conductance of the nAv-repsonisve hydrogel was found to increase with the presence of nAv. Becuse each nAv has four biotin binding sites, the existence of nAv further cross-links the hydrogel framework via binding of up to four biotin moieties resulting in the deswell of hydrogel and therefore decrease the distance between neighboring CNTs. The capability of electrical readout avoids the need of any bulky optics required for conventional optical-based assays.

Self-assembling polymeric based macromolecules have shown a great deal of promise for many biomedical material applications. While there have been some advancements, many obstacles hinder material development including a shortage in the fundamental understanding of how self-assembly occurs. This establishes the need for developing a method of modelling such interactions on an extremely small scale. Dissipative particle dynamics (DPD) is a coarse-grained meso-scale modeling technique which has proven to be a reliable tool for modeling phase behavior, yet has previously lacked the ability to capture long-range interactions without extremely high computational costs. Such interactions are vital to properly reproducing the assembly of relatively complex polymer chains. Very recently we developed a method to examine single-chain polyelectrolytes by implementing an implicit solvent ionic strength model in combination with a soft repulsive potential. This method was able to appropriately reproduce the morphological impacts on polyelectrolyte assemblies by imparting solvent effects on the self-repulsion of the individual electrolyte monomers. Our work utilizes a similar approach to model two different amphiphilic self-assembling macromolecular systems: diblock ssDNA (ssDNA bonded to a synthetic hydrophobic polymer) and elastin-like polypeptides (ELPs). Both the diblock ssDNA and ELP systems started from randomly distributed conformations throughout a periodic system then assembled into micelles. Upon micelle assembly of the diblock ssDNA, similarly coarse-grained complimentary ssDNA were added, resulting in a bridged network of micelles. From this method, we were able to observe the assembly efficiency as a function of the relationship between length of the ssDNA constituting the micelle to that of the ssDNA complimenting those chains. The ELPs studied were amphiphilic sequence controlled poly-pentapeptides. Four different 120 pentapeptide constructs were studied with varied hydrophilic and hydrophobic segment distributions. The resulting micelles formed by the different constructs were then compared to demonstrate the morphological impacts due to the change in pentapeptide distribution. We were then able to observe specific measurable differences amongst the four different micelle systems such as relative radius of gyration and aggregation. These two modeled systems provide insight into promoting and controlling the assembly of these macromolecules, ultimately building a foundation to which these components can be used to generate impactful biomedical materials.

Introduction: Triple negative breast cancer (TNBC) is an aggressive type of breast cancer for which there is no available targeted therapy, thus there is a need to develop novel and effective targeted therapy. Herein, we report a quantum dot (QD)-based multifunctional unimolecular micelles for targeted TNBC therapy. Fluorescent QDs were used as the core of the unimolecular micelle. To achieve active tumor targeting, the unimolecular micelles were conjugated with an anti-epidermal growth factor receptor (EGFR) nanobody (Nb) 7D12. Nb, as a single-domain antibody, has several advantages over whole antibodies and other antibody fragments including smaller sizes (~ 16 kDa) and higher stability. 7D12 Nb can specifically and efficiently bind to the EGFRs overexpressed on the surfaces of the TNBC cells. An anticancer drug, aminoflavone (AF), was loaded into the unimolecular micelles. The cellular uptake of the micelles by TNBC cells were studied in vitro, and the biodistribution and anti-cancer efficacy were studied in vivo.
Methods: The indium phosphide-core, zinc sulfide-shell QDs (InP/ZnS QDs) with fluorescence emission ranging from 500 to 800 nm were first synthesized and their surfaces were then modified with amphiphilic block copolymers poly(lactide)-b-poly(ethylene glycol)-OCH3/maleimide (PLA-PEG-OCH3/Mal). PLA formed a hydrophobic inner region providing a reservoir for AF. 7D12 Nbs were selectively conjugated to the distal ends of PEG by the thiol-maleimide reaction. Fluorescent QDs were used for detecting micelles both in vitro and in vivo. The cellular uptake of the micelles was studied by flow cytometry and fluorescence microscopy. The in vivo biodistribution and anti-cancer efficacy of the AF-loaded micelles were studied in an orthotopic TNBC xenograft mouse model.
Results: Stable QD-based unimolecular micelles were formed in an aqueous solution. 7D12 Nb-conjugated (i.e., targeted) micelles exhibited significantly higher cellular uptake than Nb-lacking (i.e., non-targeted) micelles in EGFR-overexpressing MDA-MB-468 TNBC Cells based on flow cytometry and fluorescence microscopy analyses,indicating excellent targeting capability of the 7D12 Nbs in EGFR-overexpressing TNBC cells. In addition, targeted micelles showed much higher tumor accumulation compared to the non-targeted ones in vivo. More importantly, the AF-loaded, targeted micelles exhibited the highest anti-cancer efficacy in an orthotopic TNBC mouse model.
Conclusion: The QD-based unimolecular micelles showed a stable fluorescence for both in vitro and in vivo imaging. 7D12 Nb conjugation significantly increased the cellular uptake and tumor inhibitory effect of the micelles in EGFR-overexpressing TNBC cells. As a result, the QD-based, Nb-conjugated theranostic unimolecular micelle can be an effective therapeutic option for TNBC treatment.

Due to the versatile optical/magnetic properties of lanthanide elements, nanoparticles doped with multiple lanthanide ions have been attracting research interest in fabricating multifunctional bio-probes integrated different diagnostic/therapeutic capabilities. However, challenges are there in properly designing and synthesizing multilayer, epitaxially-grown nanoparticles with desired size, shape and layered structures. Herein we have systematically investigated the ionic properties of lanthanides and developed strategies in preparing uniform and monodispersed multilayer lanthanide core-shell nanoparticles. These nanoparticles are concentric, with distinct layers composed of different lanthanide elements. Each element is responsible for different function and they are not interfering with each other. For example, these nanoparticles have significant enhancement in both upconverting and downconverting photoluminescence, making them good candidate for optical imaging probes and photodynamic therapy transducers. Also, these nanoparticles have enhanced relaxivity for MRI because of large particle size compared to conventional small molecule chelate contrast agents. Overall, the versatility of our system makes it highly promising for fabricating multifunctional bio-probes suitable for simultaneous imaging and therapy.

Drug carriers exhibiting pH-responsive characteristics have been mainly investigated as potential candidates for oral delivery, due to their ability to preserve the activity of the drugs, specifically biopharmaceuticals, from the harsh conditions of the gastrointestinal (GI) tract, while delivering them to the desired target. Previously, we successfully prepared microparticles composed of poly(methacrylic acid-co- methyl methacrylate) copolymers, using emulsion polymerization methods, and demonstrated their pH-responsive behavior in simulated gastric environment. In the present study, we have developed a novel, easy, and inexpensive approach for fabricating pH-responsive microspheres targeting nutrient and drug delivery to the small intestine. Scanning electron microscopy (SEM) analysis showed the formation of spherical microparticles with diameters ranging from 22.36 ± 0.11µm to 41.16 ± 0.06µm. The loading capacity of the synthesized microparticles was evaluated by encapsulating a wide range of ingredients, i.e. sulforhodamine b, lactase, and fluorescent particles (100 nm, 1µm, 4µm). pH-dependent release profile from the microparticles was monitored by measuring time-dependent fluorescence during simulated digestion process (stomach: incubation at pH 2.0 and 37 °C for 2 hours, intestine: incubation at pH 7.1 and 37 °C for 4 hours) and the microparticles morphological change and structural integrity were further characterized using SEM and fluorescence microscopy. Biomolecules encapsulated in the particles were proven to maintain at least 67% of their activity at gastric acidic conditions. Our encapsulation system offers several advantages such as easy loading, high encapsulation efficiency, and rapid release in response to pH change (acidic to neutral). This study proves that our pH-responsive encapsulation systems can be used as a general platform for applications in food, pharmaceutical, and health sciences.

Block copolymers have been widely used in nanostructured materials with various morphologies by means of self-assembly. With the oppositely charged block copolymers composed of poly(ethylene glycol) (PEG) and poly(amino acid)-based ionomers, we have recently developed polyion complex vesicles (PICsomes). PICsomes are prepared in aqueous media in controlled size from 100 to 400 nm keeping their narrow size distribution. Moreover, they can easily encapsulate hydrophilic compounds in the inner cavity and release them in controlled manner through their semi-permeable membrane structure; therefore, it is expected to have promising potential as drug delivery carriers. However, previously reported PICsomes are formed mainly by electrostatic interaction, and eventually they may disintegrate under the physiological salt condition, which is a critical issue for their application to drug delivery carriers. In this study, we introduced additional moieties into the side-chains of ionomers to exert hydrogen bonding and/or hydrophobic interaction for enhancing the stability of PICsomes. For introduction of hydrogen bonding, guanidinium group, which forms strong hydrogen bond with carboxyl group, was introduced into the side chain of polycation as an additional cation source. For introduction of hydrophobic interaction, the longer carbon chains were attached to the end of the polymer side chain. With these newly synthesized polymers, PICsomes were successfully obtained under the physiological salt condition. Moreover, these PICsomes were able to maintain their vesicle structure and narrow size distribution even in proteinous solution or at physiological temperature of 40 degree celsius. These results clearly show the potential utility of these newly developed PICsomes for biomedical applications including as a novel drug delivery carrier.

Antimicrobial resistance (AMR) is one of the biggest current healthcare challenges globally. Continued widespread antibiotic misuse has accelerated the development of resistant strains of incurable infections, responsible for over 25,000 deaths in Europe a year. Antibiotic misuse can only be mitigated through accurate and rapid diagnosis.

Lipidomics promises much to address these concerns. This rapidly developing analytical field focuses on the functional and signaling roles of lipids in biological systems and diseases, rather than considering only their structural role. The advent of lipidomics would complement existing analysis techniques and offer novel and straightforward insight into the biological workings of emerging disease strains. Combined with instant analysis techniques such as Desorption Electrospray Ionisation Mass Spectroscopy (DESI-MS), lipidomics will provide rapid point-of-care diagnosis.

Recent research focusing on the respiratory system has proven the direct correlation between the bioactive lipid composition of nasal sputum and the condition of the respiratory apparatus. However, current lipid extraction methods are slow and tedious, limiting the introduction of lipidomics as a means of routine clinical diagnosis.

This proposal involves using novel Polydimethylsiloxane (PDMS) based sol-gel synthesised gels functionalised with Octadecylsilane (ODS) to efficiently extract bioactive lipids from the nasal cavity. The functionalisation allows the in-situ extraction of lipids from biological fluids, and their retention when washed with aqueous solution to wash out biological 'contaminants' such as proteins. This results in a lipid-only containing scaffold that can be directly analysed by DESI-MS for instant lipid profiling, a much faster and efficient process than current lipid extraction.

Relative to control samples, the proposed functionalised gels retain 98% of extracted lipids even when washed through with PBS (as opposed to 9% in control scaffolds), but less than 10% of proteins. Furthermore, the scaffolds still allow 99% lipid elution from the scaffold when using a Folch solution (2:1 Chloroform:Methanol v/v). The proposed scaffolds can therefore be used an an efficient in-situ lipid extraction and separation tool for further analyisis, such as liquid chromatography (LC)-MS.

The proposed ODS-functionalisation also provides a sharper and clear signal-to-noise ratio under DESI-MS analysis than currently used methods, allowing for more precise quantification of lipid components.

When applied to clinical samples, such scaffolds could be inserted into the area of interest, removed and analysed via DESI-MS within minutes. This means of rapid lipidomics profiling has the potential to vastly improve patient diagnosis, directly benefitting short term care through time saving, whilst concurrently honing targeted vaccine options to mitigate against long-term antibiotic misuse, the major cause of AMR.

Multimodality bioimaging systems have been emerging to complement the limitations of a single imaging modality with the versatility of other imaging modalities which enable early diagnosis of diseases such as cancers. Nanomaterials including vesicles, micelles, nanoparticles and nanocapsules have been utilized as promising scaffolds for multimodality imaging by modifying their surfaces with various imaging probes and targeting ligands. However, the modification mostly performed by tedious covalent approaches often requires laborious and time-consuming multistep processes. Alternatively, some noncovalent modifications using host-guest interactions of β-cyclodextrin (β-CD) to adamantane (Ad) were reported. It, however, has an intrinsic limitation for in vivo applications due to the low binding affinity (K ~10⁴ M^-1). Cucurbit[6]uril (CB[6]) has exceptionally high binding affinity and selectivity to polyamines like spermidine (K ~10¹¹ M^-1). Taking advantage of the unique host-guest chemistry, here we demonstrate easily functionalizable multimodality in vivo imaging system using CB[6]s based polymer nanocapsule (CB[6]-PN) as a scaffold. The surface of the PN consisting of CB[6]s was successfully modified with various spermidine-conjugated functional tags (MAG3 and cyanine 7 for PET and NIR imaging, respectively) in a modular manner. Successful multimodality in vivo imaging of tumor in mice suggests that the exceptional selectivity and stability of host-guest interaction of CB[6] to spermidine even under in vivo conditions make CB[6]PN a promising platform for multimodality imaging of cancer.

In stem cell based tissue engineering, especially that uses differentiated cells, identification of cell type is of great necessity. With the growing knowledge of induced pluripotent stem cells in the recent years, many methods were developed aiming to remove undifferentiated iPSCs due to their tendency of forming teratoma. While antibodies and fusion marker protein are good enough for analysis purpose in laboratory use, they are nor applicable for examining cells for clinical use. A safe (non-toxic and uses no exogenous protein or gene) and thorough method is needed to serve as the safety-guard procedure before transplantation. To solve this problem, we have engineered synthetic peptides, which are designed to identify iPSCs in a mixed culture containing both iPSCs and differentiated cells. The synthetic peptides response to an ecto-enzyme marker of stem cells: alkaline phosphatase. By losing one phosphate group, the hydrophobic products spontaneously self assemble to form toxic aggregates, which induce death of the stem cells. Besides serving as the safety guard procedure before transplantation, we found that applying the synthetic peptides during the differentiation resulted in higher ratio of desired cells in the population at the end point. Since both peptide and mRNA can easily be manipulated to recognize marker enzymes and microRNAs that are specific to other types of cells, we believe our approach will not only facilitate the transition of iPSC technology from laboratorial to clinical use, but also have a great potential in other aspects of in biomedical cell based therapies and targeted treatments.

Supramolecular self-assembly has been widely adopted in cancer therapeutics.^1,2 One of the most used approaches is to encapsulate the cancer cells by forming hydrogels on pericellular matrix.^3-5 This “encapsulation” strategy is effective to inhibit the growth of cancer cells. However, it requires high doses to form solid gels on pericellular environments, and shows unavoidable encapsulation to the surrounding healthy cells. Taking deep insights into cell structures, cell membrane protrudes as filopodia, lamellipodia, stress fibers, microvilli, and invadopodia provided by actin cytoskeleton. The membrane protrusions evolve in diverse cell processes, such as water or nutrient uptake, cell adhesion and cell movement. Multiple trans-membrane signaling receptors accumulate and immobilize on actin skeleton of the membrane protrusions. Stimulates on membrane protrusion will be sensitively inducted and transduced into biochemical pathways. Therefore, selective self-assembly on membrane protrusions can offer direct stimulates on cells and provide precise control on cell fates.
Herein we present the design of novel hydrogelators based on ruthenium(II) complex with response to placental alkaline phosphatase (PLAP), an enzymes that is abundant on membrane protrusions and overexpressed in cancer cells. The luminescent Ru(II)-based hydrogelator contains multiple enzyme-reactive sites to facilitate PLAP-induced self-assembly. Confocal laser scanning microscopy (CLSM) images and scanning electronic microscopy (SEM) images show that nano-scaled self-assembled structures selectively attach with filopodia or locate on the tips of membrane protrusions. Self-assembly on membrane protrusions activates Caspase-8 and Caspase-3 signaling pathway and eventually induces cancer cell death. These results provide a new horizon on the precise control of cancerous cell fates by adopting enzyme-orientated self-assembled approach.

Reference:
1 X. Du, J. Zhou, J. Shi, et al. Chem. Rev., 2015, 115, 13165-13307.
2 O. Julien, M.Ｋampmann, M. C. Bassik, et al. Nat. Chem. Biol., 2014, 10, 969-976.
3 R. A. Pires, Y. M. Abul-Haija, D. S. Costa, et al. J. Am. Chem. Soc., 2015, 137, 576-579.
4 A. Tanaka, Y. Fukuoka, Y. Morimoto, et al. J. Am. Chem. Soc., 2015, 137, 770-775.
5 J. Zhou, X. Du, N. Yamagata, et al. J. Am. Chem. Soc., 2016, 138, 3813-3823.

Glioblastoma is a highly aggressive brain malignancy characterized by a low median survival of 15 months in patients after diagnosis. Enhanced tumorigenicity of glioblastoma is often associated with overexpression of the Epidermal Growth Factor Receptor (EGFR) on the cell surface. Despite this, clinically approved EGFR inhibitors (e.g. Erlotinib; ERL) have failed to provide a therapeutic benefit in glioblastoma patients due to poor transport of the small molecule chemotherapeutic across the blood-brain barrier (BBB). Direct administration of drug-loaded biocompatible materials into brain parenchyma would bypass the BBB, while affording sustained and preferential delivery of the loaded EGFR inhibitor directly to tumor cells. Interestingly, recent studies have shown synergistic activity of ERL, and the DNA damaging agent Doxorubicin (DOX), when co-administered to cells under a time-staggered ERL→DOX regimen. In this work, we design a multicomponent, syringe-injectable hydrogel material that is capable of sequentially releasing loaded ERL and DOX to tumor cells. We employ the de novo designed MAX8 amphiphilic peptide capable of folding and self-assembling under physiological conditions to form a rigid hydrogel material. Importantly, self-assembly can be triggered in the presence of free ERL, as well as DOX-loaded liposomes, allowing for co-encapsulation of the two therapeutic agents within different compartments of the resulting gel. We show that this multicomponent encapsulation strategy achieves both rapid delivery of ERL, and concomitant sustained release of DOX, under physiological environments. This time-staggered release profile leads to significant anti-proliferative and apoptotic activity towards LN229 human glioblastoma cells, even when only microgram quantities of each drug was loaded into the material. Based on these results, the therapeutic activity of these programmable hydrogels is currently being investigated in pre-clinical glioblastoma in vivo mouse models. Overall, multicomponent lipopeptidogels show significant promise as new delivery devices that can sequentially release loaded chemotherapeutics directly to brain tumor cells, while minimizing collateral toxicity to the healthy neural tissue.

Nanodiamonds (ND) with tailored surface chemistry were shown to induce vascular barrier leakiness. The ND-induced leakiness was found to be mediated by the increase in intracellular reactive oxygen species (ROS) and Ca2+. These in turn triggered the loss in endothelial cell - endothelial cell connections of the vascular barrier and also triggered quasi stable cytoskeletal remodelling. This ND mediated increase in leakiness allowed more doxorubicin drug to penetrate through the vascular barrier to reach the cancer cells. This increase in the doxorubicin penetration subsequently led to increase in the cancer killing effect. Overall, tuning the vascular barrier leakiness through ND surface functionalization could provide an important alternative strategy for the cancer nanomedicine to traverse across the vascular barrier.

Blood transfusion is one of the most common procedures for treating patients who suffer from serious blood loss or diseases that disrupt normal functions or production of blood. Not only the shortage of blood donation, but mismatching in blood type makes transfusion more difficult, as it may cause fatal immunologic reactions such as cross-type agglutination and hemolysis, resulting in life-threatening situation. Although ABO/D (Rh) blood typing is useful for finding an appropriate blood donor, people who have a Rh-negative type, a rare blood type, are very hard to get transfused because of the lack of matching blood.
To overcome the blood type mismatching problem, many researchers have tried to produce universal red blood cells (RBCs), which can be transfused to anyone regardless of their blood type. ABO/D type of blood is determined by the specific blood group antigens exclusively located on the surface of RBCs. So far, there have been three major approaches to make universal RBCs: (1) ex vivo RBC production from stem cells, (2) enzymatic removal of antigens on RBC surfaces, and (3) immunocamouflage of RBCs. Among them, immunocamouflage is a promising strategy that modifies the surface of living RBCs using nonimmunogenic materials to prevent the antibodies from binding to antigens on RBC surfaces. These surface-modified RBCs are not recognized by recipient’s immune system, therefore, could be used as universal RBCs.
Here, we report a new simple method to modify the surface of RBCs with metal-polyphenol complex composed of natural polyphenol (tannic acid; TA) and metal ion (ferric ion; Fe^III) for immunocamouflage. By adding aqueous solutions of TA and Fe^III into the suspension of RBCs, TA-Fe^III coordination complex quickly (in seconds) formed on the individual RBCs, like a shell, and the process was biocompatible and cost-effective. Successful surface modification by TA-Fe^III complex was confirmed and characterized by confocal laser scanning microscopy, scanning electron microscopy, atomic force microscopy and Raman spectroscopy. An antibody-mediated hemagglutination assay and measurement of oxygen consumption by RBCs showed that TA-Fe^III complex shell could reduce antigen-antibody reactions while maintaining the oxygen-carrying capacity of RBCs. We expect that these results would contribute to realization of universal RBCs for clinical use.

Introduction
Bioactive glass can stimulate bone regeneration [1]. However, the lack of ability to share cyclic load has limited its clinical use. Hybrids have nanoscale co-networks of organic and inorganic components reducing brittleness. Covalent bonding between components can be generated by a coupling agent. Here, polycaprolactone (PCL) was chosen as the biodegradable polymer. The challenge was to bond PCL to the coupling agent since commercial PCL lacks functional groups. Here, PCL was synthesized so that it contains glycidyloxypropyl trimethoxysilane (GPTMS) units. The objectives include: (i) synthesizing of poly (CL-GPTMS) copolymers that directly bond to silica network; (ii) further developing the polymers with different repeating units; (iii) improving hybrid mechanical properties by changing the ratio between inorganic and organic contents as well as the molecular weight of the polymer.

Experimental
Synthesis of PCL-r-GPTMS random copolymer: Ring opening polymerization was applied to polymerize Caprolactone (CL) with GPTMS at 110°C for 24 hours. Polymers were precipitated in cold methanol to remove unreacted monomers.
PCL-r-GPTMS and silica hybrid synthesis: Tetramethylorthosilicate (TEOS) was hydrolysed with water, mixed with the copolymer to form the sol. The mixture was aged and dried for 3 weeks at 40°C.
Characterization techniques: Copolymers were assessed by solution state hydrogen NMR and GPC. Hybrids were tested by TGA/DSC, FTIR, AFM and SEM. The mechanical properties were tested by compression tests. Cytotoxicity tests and cell attachments were also performed.

Result and discussion
¹H-NMR spectra demonstrated the successful copolymerization of CL and GPTMS. FTIR, AFM and SEM analyses on the hybrids confirmed the homogeneous inorganic/organic network. Compression tests showed the hybrids were flexible and the toughness was significantly improved compared to hybrids using isocyanatopropyltriethoxysilane (ICPTES) as a coupling agent [2]. The elastomeric behavior was found to be more evident with higher polymer content in the hybrids. The Young’s modulus varies from 5 MPa to 1.2 GPa and strain at failure was found in the range from 25 to 4.5 percent according to various silica content.

Conclusion
PCL-GPTMS copolymers with build-in functionality were successfully fabricated. They enabled the bottom up synthesis of the innovative sol-gel silica/PCL hybrids. These hybrids were uniform, flexible and tougher than existing hybrids. Different mechanical properties were achieved by varying synthesis parameters. Therefore the hybrids can serve as the prototype for new generation of bioactive glass/PCL hybrids.

References
[1] J. R. Jones, "Review of bioactive glass: From Hench to hybrids," Acta Biomaterialia, vol. 9, pp. 4457-4486, 1// 2013.
[2] S.-H. Rhee, J.-Y. Choi, and H.-M. Kim, "Preparation of a bioactive and degradable poly(ε-caprolactone)/silica hybrid through a sol–gel method," Biomaterials, vol. 23, pp. 4915-4921, 12// 2002.

Over the past two decades, nanotubes (e.g. carbon nanotubes, peptide nanotubes, DNA nanotubes, and protein nanotubes) have attracted extensive interest in biological applications due to their unique physiochemical properties. We report here a new platform of supramolecular nanotubes that are formed by self-assembly of rationally designed prodrugs. We have synthesized a great diversity of prodrugs of different surface chemistries and functionalities (e.g. cationic, anionic, non-ionic, and tumor-targeting ligands) that are capable of associating in aqueous solutions into a tubular morphology, with a width of approximately 10 nm and lengths on the scale of several micrometers. We further demonstrated that other functional molecules such as imaging agents and small molecule drugs can be easily incorporated into these nanotubes through passive diffusion without altering their morphology, affording a facile yet effective means to dope in a variety of different functionalities. Our in vitro results revealed that these drug-containing nanotubes exhibited sustainable drug release in the presence of glutathione, a cancer-relevant reducing agent, and showed great efficacy against U87 MG cancer cell lines. We believe that this versatile soft nanotube platform has a remarkable potential in cancer treatment and diagnosis.

Synthetic biology entails the design and engineering of cells with novel pathways and activities and is likely to be a driving force of medicine in the future. For these synthetic systems to function, multiple diverse elements ranging from DNA to small molecule drugs, need to be delivered to the same cell. We are not aware of a delivery system that permits the incorporation of both types of molecular moiety into a single delivery device. In this study we incorporated plasmid DNA and the small molecule drug, doxycycline into LbL microcapsules. We show that these components can be co- delivered to cells and the induction of luciferase gene expression confirmed that these components also interact within the cell. This enabled the demonstration of a novel intracellular regulated transcriptional circuit. LbL assembled microcapsules represent an innovative multifunctional tool for the delivery of synthetic biology systems.

The ultimate goal of drug delivery is to transport sufficient drugs to disease sites while at the same time minimizing their entry to healthy tissues. Although a variety of nanoplatforms have been developed, it still remains a challenging task to create nanocarriers with both prolonged circulation time and effective cell uptake capacity due to the required contradictory properties. In this work, we show that rationally designed drug amphiphiles could self-assemble into ultralong supramolecular nanotubes in aqueous solution capable of transforming into smaller objects under dilution and/or sonication. Transmission electron microscope and dynamic light scattering were used to monitor the morphologically transforming process. Our in vitro results revealed that the fragmented smaller objects can be effectively internalized into cancer cells, in sharp contrast to the poor cellular entry of the ultralong nanotubes. We future demonstrated that these nanotubes can be used to deliver anticancer drugs of a different type.

We describe recent studies on design, characterization and automated planning and control of stimuli responsive untethered soft grippers. We utilized photopatterning to fabricate these grippers composed of a rigid, non-swellable SU-8 layer and a second magneto-thermally responsive (pNIPAM-AAc doped with iron oxide) hydrogel layer. These gripper structures spontaneously and reversibly closed and opened on heating and cooling. Further, the incorporation of biocompatible magnetic nanoparticles allowed them to be controlled by magnetic fields. Additionally, closed-loop control software was used to regulate the current in a three-axis electromagnetic coil system, remotely manipulating the local magnetic field gradients to move the magnetic grippers. Finally, a Peltier element was used to change the temperature and control the opening and closing motion. Thus, a fully automated system for moving and opening the soft-grippers was developed. We discuss application of this system for pick and place of a variety of cargo including porcine muscle tissues for potential applications in microassembly, soft-robotics, medicine and minimally invasive surgery.

A hydrogel, consisting carboxylic acid group and N-isopropylacrylamide as pendants on its polymeric network, usually exhibits volume expansion when being deprotonated or shrinking when being heated. Here we demonstrate an anti-intuitive case that a hydrogel, containing carboxylic acid group at the crosslinking points of the polymeric network, shrinks upon deprotonation or expands upon heating. Moreover, solid state ¹³C-NMR reveals that the unexpected shape change originates from the high percentage of the crosslinker in the polymers. As the first example of the use of responsive crosslinker to control the pH responsiveness of the nanogels and increase the loading of charged groups, this work illustrates a new way to design soft matters with unusual behaviors.

Conducting polymers have been widely utilized for biosensors and bioelectronics because they offer a suitable matrix for efficient entrapment of the biorecognition elements (e.g. proteins and enzymes) without labeling, chemical surface modification, or templating steps that may interfere with bioactivity of the biorecognition elements and signal transduction. However, the development of highly sensitive and selective microarrays of conducting polymer (CP) biosensors to detect biologically critical molecules in vivo has been challenging due to high noise level of detection resulting from low electrode surface areas. In typical biosensors, surfaces are functionalized with a ligand having high affinity for the target molecule. Conventional chemical approaches, such as self-assembled monolayers (SAM) run the risk of altering the molecule’s functional group, and thus ligand-binding properties. While many works have attempted to increase surface areas of microelectrodes using hard and soft templating of CPs, less study has been done to investigate the effect of CP thickness and roughness on the efficiency of detection and entrapment, respectively. In this work, we investigate two common CPs, poly (pyrrole) (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT), for entrapment of avidin using galvanostatic (GSTAT) and potentiostatic (PSTAT) methods. PPy has been considered as the most suitable matrix for entrapment due to its excellent aqueous solubility. PEDOT displays superior chemical stability and electrical conductivity, making it an ideal candidate for high sensitivity in the long term. The PPy and PEDOT films will be electrodeposited on Au electrodes from a solution containing EDOT or Py monomers and avidin as the dopant in galvanostatic mode (i.e. current density from 0.1 to 1.5 mA/cm²) or potentiostatic mode (i.e. voltage from 0.7 to 2.0V) and at set intervals from 1-20min. Each sample will be analyzed using scanning electron microscopy (SEM) and scanning atomic force microscopy (AFM) to assess any trends in surface roughness and film thickness. Preliminary data for PEDOT films formed via GSTAT showed an increase in surface roughness from 9.73 nm at 1 min to 22.4 nm at 20 min for current density of 1.0 mA/cm². The samples under SEM showed film thickness increase from 0.1um at 1 min to 2.8 um at 20 min. Qualitative analysis showed similar trends for other current densities, and increases in roughness with increasing current density. The knowledge gained here will be used to entrap vital biomolecules within the CP matrix physically, and hence maintain original biological functionality. Ongoing studies seek to optimize both avidin entrapment and CP film characteristics to fabricate efficient biosensors for real-world applications.

Since cancer is an extremely heterogeneous disease of origin, scientists are always trying to define novel approaches that can eliminate this disease. Over decades now, surgery, radiotherapy and chemotherapy have been the conventional methods to eradicate cancer. Unfortunately, cancer resistance has developed, in which tumor cells became resistant to the majority of chemotherapeutics. Consequently, people started to use combination therapy as a more intensified protocol to counteract the aggressiveness of cancer. However, the results are not satisfactory till now and lots of optimizations are needed in order to make sure that synergistic not antagonistic effects are happening. That is why scientists started to revisit cancer immunotherapy field after long years of its discovery. They are rapidly defining new approaches for harnessing the immune system against cancer. Different methodologies are developed in the last ten years, yet optimizations are still in process. Nanotechnology is a promising tool in harnessing immune system against cancer. However, targeting as a technique still paving the way for the optimum particle-cell interaction. Bioengineering the immune system using nanomaterials as delivery vehicles is meant to understand, target and manipulate the immune system. This is of great interest owing to the significant role of immunity in disease control. In the current study, we aim at targeting immune cells infiltrating the tumor. The challenge is that the population of cancer cells is much more than the immune cells. In this study, the response of different immune cell lines towards internalization of different engineered lipid-based nanoparticles (NPs) was investigated at different time frames. Three sets of fluorescently labelled nano-liposomes were engineered as a model for different surface charges, the cationic, anionic and near neutral. Physical stability of the NPs was evaluated by monitoring the changes in size and zeta potential. Dendritic Cells, macrophages, T-cells and natural Killer cells were isolated from the tumors of the B16 melanoma tumors and spleens of the mice. The three sets of NPs were tested against the isolated cell lines. The cellular uptake (internalization) was assessed by normalizing the fluorescence of the cells against their protein concentration, then all samples were acquired to flow cytometry, and shifts in fluorescence histograms on horizontal axis were monitored against PE channel on the vertical axis. Results reveal the presence of preferential internalization of specific surface charge over others in some cell lines in different time frames. For the first time differences in the internalization pattern are reported in the same immune cell line isolated from two different contexts tumor and spleen. These results might serve as a guideline for a rational design of successful nano-carriers that can maximize the targeting and hence the therapeutic efficacy towards certain population of immune cells.

Manipulation of nanocomposites in conjunction with biomolecules is crucial for the development of novel bio-conjugates for applications in medical areas, for both, diagnosis and therapy. These so-called theranostic materials represent the state-of-the-art in the development of nanoscale-based materials for fighting cancer. Gold nanorods (AuNRs) and graphene have found promising applications in medicine, mainly because of the absorption band in the infrared region exhibited by these materials. The absorption in the near infrared region makes them appropriate for in vivo photothermal applications due to the maximum radiation penetration through tissue. Besides, investigations on novel nanomaterials for photo-hyperthermia applications are of great importance to understand the toxicity of nanomaterials at the molecular scale and the influence of lipids in the uptake process, bringing important benefits to the field of personalized nanomedicine. We report on the development of a nanosystem comprising cell membrane-coated AuNRS, which have been synthesized by colloidal seed-mediated, surfactant-assisted approach, followed by coating with human lung adenocarcinoma epithelial cell (A549) membrane. Glutamine-graphene oxide nanocomplexes were also synthesized and applied in the photohyperthermia studies. The nanoconjugates presented higher toxicity to cancer cells compared to healthy fibroblasts. The incorporation of gold nanorods into real membrane monolayers was also studied using Langmuir techniques via kinetics absorption and surface pressure measurements and revealed significant differences on how the AuNRs interact with the cell membranes depending on the size of the gold nanorods, indicating that the lipids present in the covering membrane exerted high influence on the uptake process. These results revealed the potential of cell membrane-coated nanomaterials and open opportunities for the development of more efficient nanosystems for cancer applications.

Cell motility plays a critical role in major physiological events including embryogenesis, wound repair and metastasis. It is well-known, that extracellular matrix (ECM) provide external cues to direct and influence cellular behavior. It is through such cell-ECM interactions, that tissues can be orchestrated to move in a concerted manner. Many tissue-engineered scaffolds are designed to mimic the ECM, and to provide cells with appropriate mechanical, biological and topographical cues. While a variety of biomolecules have been used in cell-ECM studies, there have been relatively little focus on integrin-mediated cellular behavior. In our laboratory, we develop a novel protein-based hydrogel platform, where we can independently control the mechanical, biological and topographical cues. By systematically varying the hydrogel properties, we can study the effect of two or more material properties on cell motility. For instance, when integrin-specific proteins were incorporated within the hydrogel, we found that cells migrating on substrates that bind to the alpha5beta1 integrins, exhibit a significantly different behavior, compared to on substrates that bind to the alpha3beta1 integrins. We are now investigating if these differences may vary in response to changing mechanical stiffness or in the presence of topographical cues.

The diagnosis and treatments of pancreatic cancer remain difficult owing to the complicated interactions between components in the pancreatic tumor niche. Studies have shown that pancreatic stellate cells (PSCs) are the major stromal cells affecting the growth and metastasis of tumor cells by means of paracrine effects and extracellular matrix (ECM) protein deposition and organization. The complex network of biochemical and biophysical cues in the pancreatic desmoplasia not only presents challenges to the fundamental understanding of tumor progression, but also hinders the development of therapeutic strategies against pancreatic cancer. PSCs remain in a quiescent/dormant state until they are ‘activated’ by various environmental cues. While the mechanisms of PSC activation are increasingly being described in the literature, the influence of matrix stiffness on PSC activation is largely unexplored. The main hypothesis of the current study is that matrix stiffness affects myofibroblastic activation of PSCs. To test this hypothesis, we have prepared cell-laden hydrogels with dynamically tunable stiffness for probing the myofibroblastic activation of PSCs in three-dimension (3D). To mimic the stiffening environment in a tumor niche, we designed cell-laden hydrogels with in situ stiffening capability. This was achieved by using peptide linker with additional tyrosine residues. Although tyrosinase has been explored for hydrogel crosslinking and in situ cell encapsulation, this crosslinking mechanism has not been explored for in situ stiffening of cell-laden hydrogels. In situ stiffening is achieved by incubating the cell-laden hydrogels in media containing tyrosinase, an enzyme that catalyzes the oxidation of tyrosine into dihydroxyphenylalanine (DOPA), DOPA quinone, finally into DOPA dimer. The formation of DOPA dimer led to additional crosslinks and thus stiffening the cell-laden hydrogel. In addition to systematically studying the various parameters relevant to enzymatic reaction and hydrogel stiffness, we also designed experiments to probe the influence of dynamic matrix stiffening on cell fate. Protease-sensitive peptides were used to crosslink hydrogels, whereas integrin-binding ligands (e.g., RGD motif) were immobilized in the network to afford cell-matrix interaction. PSC-laden hydrogels were placed in media containing tyrosinase for 6 hours to achieve in situ gel stiffening. We found that PSCs encapsulated and cultured in stiffened matrix (modulus from 1 to 3kPa) expressed higher level of αSMA and hypoxia-inducible factor 1α (HIF-1α), suggestive of a myofibroblastic phenotype. In summary, this hydrogel system provides a convenient and cytocompatible means of studying mechanobiology in 3D.

Thrombosis is the formation of a blood clot (thrombus) inside a blood vessel, obstructing blood vessels to critical organs such as heart and brain through the circulatory system and is a leading cause of death, nearly a third of the deaths each year in the western world. Thrombosis is characterized by the recruitment and aggregation of platelets and fibrin deposition. Fibrin exists in the form of cross-linked mesh deposited both inside and on the surface of atherosclerotic plaques and plays an important role in the stabilization of thrombus. Hydrogen peroxide (H₂O₂) is a key mediator of platelet activation and aggregation and therefore, H₂O₂-mediated platelet activation is one of mechanisms leading to prothrombotic phenotypes. By taking the advantages of unique physicochemical and biological characteristics of thrombus such as the elevated level of H₂O₂ and abundance of fibrin, we developed fibrin-targeted imaging and anti-thrombotic nanoparticles, termed FTIAN for imaging and therapeutics for thrombosis. FTIAN was designed to target fibrin specifically to image thrombus, scavenge H₂O₂ and prevent platelet activation, leading to the inhibition of thrombus formation in injured vasculature. When desired, FTIAN could also serve as a drug delivery system to occlusive thrombosis. In the present work, we report the rational design of FTIAN and its translational potential as a nano-theranostic agent for obstructed thrombotic diseases. FTIAN consists of H₂O₂-scavenging boronate antioxidant fluorescent biopolymer (BAP-IR) and fibrin-specific lipopeptide (CREKA). FTIAN of ~120 nm could rapidly scavenge H₂O₂ and exert potent antioxidant and anti-inflammatory activity in activated macrophages and platelets. In a mouse model of FeCl₂-induced carotid arterial thrombosis, FTIAN imaged specifically thrombus formation and remarkably suppressed the thrombus formation. We anticipate that FTIAN holds great potential as theranostics for obstructed thrombotic diseases.

Actively targeted drug delivery systems are widely studied to improve the therapeutic efficiency and reduce the side effects of chemotherapeutic agents. This study used Doxorubicin as a model chemotherapeutic agent due its high potency, its wide use for treatment of various types of cancer and its well-known side effects. Although doxorubicin has been the focus of many nanopharmaceutical studies, it remains a challenging drug to formulate. Its hydrophilic nature limits to a great extent its loading efficiency to very low values. It also has two ionizable functional groups which the formulation process highly sensitive to pH changes.

This study introduces a novel core/shell drug delivery system based on electrostatic interactions. The system includes the anticancer agent, doxorubicin, coated by negatively charged chitosan-graft-polyacrylate copolymer which is then coated by PEGylated trimethyl chitosan. The function of the negatively charged inner layer is to improve the loading efficiency of the drug and to provide synergistic anticancer activity. The outer layer provides an outer positive charge to allow intracellular uptake. The PEGylation in turn provides immune stealth characteristics and prolonged circulation time.

Several formulation parameters were optimized systemically using Design Expert V10 software to determine the relations between different factors as the pH of the medium, amount of chitosan-g-polyacrylate and PEGylated trimethyl chitosan. The developed experimental model was used to optimize the size, charge (higher positive charge) and loading efficiency of the formulation. The formulations were chemically conjugated to glycerrhetinic acid and lactobionic acid which accumulate in the liver allowing active targeting of hepatocarcinoma.

Formulations were characterized using dynamic light scattering, infrared spectroscopy, differential scanning calorimetery and scanning electron microscopy. Loading efficiency as well as drug release profile were studied using UV-Vis spectrometery. The efficiency of the developed formulations was evaluated using cytotoxicity assay on HCC cell line as well as mice animal model with induced hepatocellular carcinoma.

The used drug loading efficiency of the developed delivery system was higher than most of the previously reported formulation (40 – 50% at a drug to polymer ratio of 1:3). The size of the optimum formulation (300 – 500 nm) allowed passive targeting of the tumor. The positively charged nanoparticles provided significantly higher intracellular uptake compared to the negatively charged control particles. The formulation showed potent anticancer activity in cell line assays. Moreover, the developed formulation provided sustained release of the loaded doxorubicin for about 4 days. The formulation was able to accumulate selectively in the liver tumors with lower side effects compared the free doxorubicin.

It is possible to control geometrical structures of soft materials in macro-scale by utilizing interfacial instability or mechanical instability, e.g., fingering patterns of viscous liquid and buckling patterns of gels during swelling/deswelling process. These patterns are expected to be applied in dynamic materials having smart functions such as capturing/releasing and mass-transportations. Here we introduce a dissipative structure through a non-equilibrium process between hydration and deposition in drying of an aqueous liquid crystalline solution composed of megamolecule polysaccharides, from a limited space. By controlling geometries of the evaporation front, multiple nuclei emerge to grow upright membranes with uniaxial orientation. Notably, the uniaxial orientated membrane composed of rod-like microdomain is rationally formed along to the dynamic three-phase contact line. We envision that not only such a uniaxially-oriented membrane will be applicable to soft biomaterials with directional controllability but also such a macroscopic space-partitioning will help understandings of spatial partitioning laws in natural products under drying environment.

The development of biodegradable polymeric nanofiber scaffolds for a potential effort to repair injured nerve cells is of great interest in nerve tissue engineering applications. Poly (L-lactic acid) (PLLA) has been widely used in nerve conduit studies due to its biocompatibility, easily shaped properties and degradation to low toxic lactic acid. However, its hydrophobicity and lack of binding sites for cellular activities restricts its use as implants. In this regard, this study involves the incorporation of GO into PLLA either electrospun GO with PLLA or coating GO onto the PLLA nanofibers for enhancing mechanical properties, conductivity and hydrophilicity of PLLA to make it suitable for potential peripheral nerve regeneration application. For this purpose, PLLA and PLLA/GO nanofibers were prepared via electrospinning process by dissolving PLLA and GO in chloroform (Chl) and dimethylformamide (DMF) binary solvent. The processing parameters (feed rate, tip to collector distance and mandrel speed) and solution parameters (the concentration of PLLA and GO and composition of binary system) were optimized to adjust physical and mechanical properties of nanofiber in terms of size, porosity and biologically active affinity for cellular interaction. The morphology and composition of the developed electrospun fibers were characterized via Light Microscopy, Scanning Electron Microscopy (SEM), Raman Spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), tensile test and contact angle measurement. The morphological results showed that using Chl/DMF ratio of 8/2 for 7wt% PLLA led to the formation of bead free and thinner PLLA fibers than fibers produced from other concentration of PLLA. Moreover, the addition of the GO resulted in decrease of the average diameter of PLLA fibers from 828 nm to 490 nm and the thinnest nanofiber structure was obtained by addition of 10 v/v % GO. The sonication time of GO highly enhanced the porosity of the nanofibers, namely the porosity of the nanofibers increased with increasing sonication time. However, the effect of sonication time on the average fiber was not clear. In addition, there is no obvious trend of change in nanofibers porosity of the nanofibers with increasing concentration. Therefore, further investigation will be performed to investigate the effect of the concentration and sonication time of GO on porosity. The raman spectroscopy exhibits peaks at bands of 1775, 873 and 1455 cm^-1 that are attributed to C=O stretching, C-COO stretching and CH₃ asymmetric deformation respectively for PLLA and 1379 and 1599 cm^-1 which represent structural imperfections and sp2 domain of carbon atoms respectively for GO. Hence, it can be said that raman peaks confirmed that GO incorporated in the structure of PLLA in either fabricated composite nanofiber or coated nanofibers. The incorporation of GO significantly improved the tensile strength from 2.25 MPa of pure PLLA to 8.13 MPa, 10.44 MPa and 12.93 MPa and young’s modulus from 81.15 to 309.33, 381.026 and 567.60 MPa with 0, 5, 7.5 and 10 v/v% GO addition respectively. Moreover, the effect of addition of GO into or onto electrospun fiber on the degradation rate of fibers was investigated. The results revealed that the addition of GO led to enhanced chemical and physical properties of fibers which is promising for nerve regeneration applications.

Ultrasmall polymer-inorganic hybrid nanoparticles with sizes below 10nm, i.e. below the cut off for renal clearance, offer great promise in the nanoparticle based detection and treatment of disease. Despite a large variety of existing hybrid nanoparticle platforms only a small number has been successfully translated from the laboratory to the clinic. One of the challenges preventing the translation of experimental particle systems is the lack of reliable and comprehensive studies of the correlations between particle size, structure, and surface chemistry with biocompatibility and pharmacokinetics (PK). This talk focuses on fluorescent core-shell silica nanoparticles referred to as Cornell dots or C dots. A new aqueous synthesis approach to C dots will be discussed borrowing concepts of living polymerization to control size distributions.¹ Particle growth is initiated simultaneously; all particles grow for the same time, and termination is accomplished via addition of a poly(ethylene glycol) (PEG) bearing silane.² It will be demonstrated that this synthesis system provides unprecedented control of ultrasmall silica nanoparticles in terms of particle size, geometry and surface chemistry. Employing this approach multiple polymer-inorganic hybrid silica-based nanomaterials have been developed with different structures and tunable dimensions in the <10nm size regime, whose preparation and detailed characterization will be discussed. A particular focus will be on the mechanism of nanoparticle surface modification, which enables not only the efficient termination of particle growth but also the precise control of particle surface properties.³ In addition, the mechanism of surfactant micelle mediated growth of mesoporous or single-pore C dots (mC dots) will be discussed with potential in theranostic applications.⁴ The resulting silica-based polymer-inorganic hybrid nanomaterials (C dots) have already been approved by FDA as investigational new drugs (IND) for multiple human clinical trials now ongoing at Memorial Sloan Kettering Cancer Center (MSKCC) in New York City.

(1) K. Ma, C. Mendoza, U. Werner-Zwanziger, J. Zwanziger, U. Wiesner, Chem. Mater. 27, 4119-4133 (2015).
(2) K. Ma, U. Werner-Zwanziger, J. Zwanziger, U. Wiesner, Chem. Mater. 25, 677-691 (2013).
(3) K. Ma, D. Zhang, Y. Cong, and U. Wiesner, Chem. Mater. 28,1537-1545 (2016).
(4) K. Ma, H. Sai, U. Wiesner, J. Am. Chem. Soc. 134, 13180-13183 (2012).

The plasma membranes of cells are heterogeneously arranged and highly compartmentalized over micro-and nanometric scale. These compartmentalized domains are called lipid rafts and found to carry out various functions such as cell signaling and membrane protein trafficking. Inspired by nature, we intentionally introduced phase heterogeneities into lipid film mesophases by blending amphiphilic block copolymers at several lipid/polymer ratios. We observed that two-component lipid-polymer hybrid films can be supported in multi-bilayer format. The multi-layers display lateral phase segregations akin to “raft-like” domains in cholesterol containing lipid bilayers. Polymer-rich and lipid-rich domains are confirmed to coexist in each of a single bilayer by grazing incidence x-ray diffraction and confocal fluorescence microscopy. Interestingly, we found evidence that like-domains align on top of each other across the bilayer stack, thereby making phase separation three dimensional. We utilize this distinctive domain structure of hybrid films for local drug delivery applications where phase separation can be advantageous in terms of drug stability and controlled release.
Paclitaxel is known as one of the most effective anti-cancer drug for the treatment of breast and ovarian cancer. It has been commonly administered through long-term systemic injection, which brings about unwanted adverse reaction. The most common adverse effects include infusion related reactions and neutropenia. Accordingly, local drug delivery to the site of disease can be a more preferable option for delivering paclitaxel, as in drug-eluting medical implants. However, the local delivery of paclitaxel still has limited clinical applications due to crystallization within the delivery matrix. When paclitaxel molecules are individually entrapped within a membrane, they are in a metastable state and tend to precipitate out to form a more stable crystalline form. In membranes composed of single-component, the paclitaxel molecules still possess the freedom to diffuse laterally giving them in-plane fluidity, which could accelerate the aggregation and crystal formation. In this respect, the coexistence of polymer-rich and lipid-rich domains in hybrid membranes would generate phase boundaries due to different physicochemical properties which could restrict the lateral diffusion of paclitaxel hindering crystallization.
We observed that the lipid-polymer hybrid films can incorporate a high content of paclitaxel and most interestingly, they display a unique paclitaxel release behavior that deviates from single-component films. We propose that synergistic drug release of hybrid films arises from a modified diffusion pathway exerted by the interfaces between different domains. This work shows that morphology design of hybrid lipid-polymer film structures with phase separated domains leads to advanced surface-based drug delivery systems that would not be realized with neat lipid or polymer systems.

Three-dimensional spatially coherent thin films (3DSCTFs) are being developed as chemical sensing elements, scaffolds for tissue engineering, or reservoirs to store molecules for controlled release. Due to the strong anisotropy of a 3DSCTF, the adsorption of dielectric materials, such as organic molecules, modulates the birefringence of the 3DSCTF; this birefringence modulation is measureable by generalized ellipsometry (GE). The 3DSCTFs are fabricated via electron-beam glancing angle deposition onto quartz crystal microbalance with dissipation monitoring (QCM-D) sensors, allowing for optical and mechanical measurement of adsorption processes onto the 3DSCTFs. This contribution discusses two applications of functionalized 3DSCTFs [1,2].

Temperature and pH-responsive polymer brushes were grafted onto Si-SiO₂ 3DSCTFs, and their swelling behavior and interactions with bovine serum albumin protein (BSA) were monitored with GE/QCM-D. GE can differentiate whether polymeric material is above the 3DSCTF or within the void spaces between individual nanostructures, and QCM-D is sensitive to the liquid solvating the adsorbate materials.

Titanium 3DSCTFs of varying topographies were evaluated for their influence on protein adsorption, cell adhesion, and cell proliferation. The amount of fibronectin adsorbed onto 3DSCTFs was measured by GE/QCM-D, and mouse fibroblast and mouse mesenchymal stem cell adhesion and proliferation on bare and fibronectin-coated 3DSCTFs and flat Ti surfaces were studied using a live/dead stain and WST-1 proliferation assay, respectively. It was found that the surface topography had an important role in cell adhesion and proliferation. The slanted 3DSCTFs with greater spacing between adjacent nanocolumns enhanced cell proliferation the most. Although disordered rough surfaces had been studied for this application in the past, ordered rough surfaces like functionalized 3DSCTFs have the potential to be exploited as scalable platforms for controlled loading and releasing of biomolecules for cellular uptake.

[1] M. Koenig et al., Anal. Bioanal. Chem., 406, 7233-7242 (2014).
[2] T. Kasputis et al., Acta Biomaterialia., 18, 88-99 (2015).

There is little doubt that modern medicine has brought great value to humanity. It has increased our life expectancy and overall quality of life. This is, in no small way, due to a very high level of synthesis control, a comprehensive knowledge of the properties of drugs from the most basic (e.g. size and mobility), to complex interactions in vivo. However, drugs which are presently on the market are not without drawbacks, including undesirable physicochemical properties and limited control of their biodistribution in vivo. Various strategies, such as antibody conjugated drugs and nanoparticle targeting vehicles are presently being evaluated to possibly address those and other present challenges, which in turn have opened many new lines of inquiry. One of the focal points of the discussion has been the design of nanomaterials with controlled pharmacokinetic properties.
Progress in the field has been slow partially due to the many challenges associated material application in vivo, lack of characterization techniques, definitions and generally a critical volume of reliable data. Of special interest are the behavior of various nanomaterials in biologically relevant conditions, their stability and physicochemical properties (e.g. IEP, charge density, density of functional groups, conformation of ligands and others) and interactions with biological units, i.e. proteins, cells, etc. To accomplish this we started from a standard fluorescently labelled, spherical silica particle model which was consequently functionalised and finally conjugated with a protein, in this work Transferrin (Tf). Each step was studied by thoroughly characterizing the material using standard and novel characterization approaches.
We study the effect of particle architecture on its biokinetic properties by systematically tuning the surface properties. In our work we have focused on controlling the surface design and characterize its properties, specifically ligand conformation, protein binding site accessibility and surface potential in an effort to understand how those different factors impact product functionality. Indeed our results suggest that there is a strong correlation between all of those aspects and particle – receptor interactions. The surface ligand density, in this case polyethylene glycol (PEG), had a profound impact on the biological behavior of the final product. This was estimated by quantifying the particle fluorescent signal of A549 cells which had their Tf receptor silenced and comparing it to a control population. Further investigation showed that the architecture of the polymer layer is also a factor which should be taken into account.
This work underlines the need for a more comprehensive understanding of ligand layers and how they affect downstream medical application of artificial materials.

In Nature, a significant pH gradient exists across the endocytosis pathway where the pH begins at ~7.5 after initial engulfment and decreases to ~5.2/~4.5 in the late endosome/lysosome [1]. As such, there is considerable interest in engineering synthetic pH-sensitive nanocarriers to take advantage of this gradient for spatially and temporally targeted drug delivery. Due to its intrinsic programmability, ease of integration with other functional nucleic acids, and extremely small size, DNA has emerged as an advantageous material to design these pH switches.

In this work, we performed the first in vitro selection for pH-activated DNA nanostructures (PADNAs). We screened a large ssDNA library (10¹³ random sequences) and found 10 sequences that stably sequester their payload, FDA-approved antisense DNA drug Mipomersen, in an inactive state at pH 7.5, but efficiently release it at pH 5.2 by switching structure. For example, we identified a molecule, PADNA-1, that acts with tremendous pH-selectivity – achieving up to a ~145-fold increase in payload release at pH 5.2 vs. 7.5, which would enable tightly regulated drug delivery. PADNAs possess a number of additional advantageous features for potential drug delivery applications. For example, we found that PADNA-1 releases Mipomersen in response to endosomal pH gradients at a rate well-suited for continuous distribution throughout the endocytosis pathway (~60% total Mipomersen released in 60 minutes). Moreover, our PADNAs are nanostructures of extremely small size, ~34 nm in length, which may enable more efficient cellular uptake.

Intriguingly, these high-performing molecules showed no sequence similarity to previously described pH-active motifs and we hypothesize that we have developed entirely novel pH-activated nanostructures. We investigated loss-of-function mutants of PADNA-1 and found that selection placed noncanonical C●A⁺ mismatches at specific locations in the sequence, which enabled low-pH structure-switching. Our PADNAs appear suitable for potential applications in pH-triggered drug delivery, real-time monitoring of in vivo pH changes, and the development of pH-sensitive nanomaterials.

[1] R Duncan and SCW Richardson. “Endocytosis and Intracellular Trafficking as Gateways for Nanomedicine Delivery: Opportunities and Challenges.” Mol. Pharmaceutics. 2012.

Cancer remains a major challenge to public health.¹ The ideal cancer therapy should selectively kill cancer cells without harming normal cells.² However, current chemotherapeutics show severe side effects to normal tissues due to their failures in identifying generic differences between cancer cells and normal cells. By taking advantage of the generic differences of certain enzymes’ expression levels between normal cells and cancer cells, we have developed an anticancer nanomedicine based on the enzyme-instructed supramolecular assemblies of small molecules.^6,7 Departing from the current dogma of using tight and specific ligand-receptor interactions, this new method could selectively generates assemblies of small molecules in-situ on cancer cells, thus greatly reducing the side effects to normal tissues by selectively killing only cancer cells. Despite these advancements, the concentrations of those molecules required for inhibiting cancer cells still are quite high (e.g., 300-500 µM).^6-8 Thus, there is a need for an effective strategy to increase the efficacy of self-assembling molecules for cancer inhibition. In this work, we demonstrate that a simple and minimal modification of the C-terminal of a D-tripeptide enhances the self-assembling ability of the D-tripeptide derivative, drastically increasing the efficacy of cancer cell inhibition.⁹ This approach increases the inhibitory activity by more than an order of magnitude. Moreover, our results indicate that the modification preserves the exceptional selectivity against cancer cells via the process of enzyme-instructed self-assembly. Further study confirms that these pericellular supramolecular assemblies induce cell necroptosis. As the first report on the merit of C-terminal modification for generating effective anticancer peptides, this work illustrates a facile strategy to explore the structure-activity relationship of short peptides, over multiple length scales, for developing a fundamentally new approach that kill cancer cells via enzymatic reactions.


(1) Biemar, F.; Foti, M. Cancer Biol. Med. 2013, 10, 183.
(2) Ferrari, M. Nat. Rev. Cancer 2005, 5, 161.
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(4) Kohn, E. C.; Sarosy, G.; Bicher, A.; Link, C.; Christian, M.; Steinberg, S. M.; Rothenberg, M.; Adamo, D. O.; Davis, P.; Ognibene, F. P.; Cunnion, R. E.; Reed, E. J. Natl. Cancer Inst. 1994, 86, 18.
(6) Kuang, Y.; Shi, J.; Li, J.; Yuan, D.; Alberti, K. A.; Xu, Q.; Xu, B. Angew. Chem., Int. Ed. 2014, 53, 8104.
(7) Shi, J.; Du, X.; Yuan, D.; Zhou, J.; Zhou, N.; Huang, Y.; Xu, B. Biomacromolecules 2014, 15, 3559.
(8) Pires, R. A.; Abul-Haija, Y. M.; Costa, D. S.; Novoa-Carballal, R.; Reis, R. L.; Ulijn, R. V.; Pashkuleva, I. J. Am. Chem. Soc. 2015, 137, 576.
(9) Feng, Z.; Wang, H.; Du, X.; Shi, J.; Li, J.; Xu, B. Chem. Commun. 2016, 52, 6332.

Numerous natural biological processes – including tissue repair and regeneration – are exquisitely sensitive to both the location and timing of biological signals and drugs. This motivates the development of on-demand systems capable of directing cell behaviour through biological signalling. Plasmid-DNA is one such signal that can utilise a cell’s own machinery to stimulate the production of encoded proteins. The overall aim of this research was to develop an on-demand alginate-based system for delivery of plasmid-DNA-nanoparticles (pDNA-NPs) using ultrasound (US) as the external stimulus to trigger their release. It was hypothesised that the baseline release could be eliminated to near-zero by the physical entrapment of the pDNA-NPs (>50 nm) within alginate pores (<10 nm) and that release could be switched ‘on’ during US and ‘off’ when the US stimulus is removed as the ionically crosslinked gels self heal. The release of pDNA encoding green fluorescent protein (GFP) from these systems was evaluated and its maintained bioactivity in rat mesenchymal stem cells (rMSCs) were tested.
To test this hypothesis, pDNA-NPs were created by condensing pDNA encoding GFP with polyethylenimine (PEI) at varying N/P ratios (0 – 7) and recording their transfection efficiencies in rMSCs. Low molecular weight alginate (L; Sigma) and high molecular weight alginate (H; Pronova) was mixed at various ratios (1 – 1.5% L : 0 – 1% H), pDNA-PEI (N/P = 7) incorporated and microparticles formed by electrospraying (Spraybase R Perfector) (22.5 μg pDNA/mg alginate). The pDNA-NP microparticles were stimulated at a range of US intensities (25 – 45% Amplitude) and cycle lengths (1 – 7.5 min), and the release was recorded. The effect of different payloads (pVEGF) and vectors (chitosan) was also explored. Finally, the US-released and diffusion released pDNA-NPs were incubated with rMSCs and GFP expression recorded.
The pDNA-NPs at N/P 7 yielded the highest transfection efficiency over a 7- day period with a transfection efficiency of 32±2%. Increasing the alginate concentration of the pDNA-NP microparticles resulted in a reduction in overnight diffusion release and a combination of H_0.75% + L_1% demonstrated the most dramatic US vs. diffusion profile (6500-fold increase in release rate vs diffusion at 35% US amplitude, 1min). No significant differences were observed for a different vector (chitosan) or pDNA payload (pVEGF – vascular endothelial growth factor) when compared with pGFP + PEI). Finally, the released pDNA-GFP particles remained bioactive with GFP expression observed at day 3; the low number of diffusion-released particles resulted in very low expression.
These results indicate that this on demand system could be utilized to temporally control the release of pDNA and switch genes on at select timepoints. Ongoing research will further demonstrate this technique with therapeutic genes and more fully explore the effect of pDNA delivery timing on regeneration processes.

Rosette Nanotubes (RNTs), a self-assembled supramolecular nanomolecule composed of fused guanine-cytosine (G^C) bases, provide a novel and innovative modality for the delivery of gene therapeutics to target cells with high efficacy. This study aims at utilizing RNTs as a nanocarrier platform for the delivery of small interfering RNA (siRNA) to knockdown oncogenic genes to facilitate the elimination of cancer from the body. By conjugating positively charged lysine functional groups to the surface of the RNTs, the nanotubes gain the ability to complex negatively charged siRNA through electrostatic interactions. Through specialized FRET-labeled siRNA and gel retardation assay, we have shown that cationic charges on the RNTs strongly affect the binding interaction and the intracellular delivery of the RNT-siRNA nanocomplex. Furthermore, we have observed higher levels of intracellular siRNA delivery utilizing the RNTs as compared to commercially available Lipofectamine through the use of fluorescently labeled siRNA. Improved gene silencing capabilities were also exhibited compared to commercially available siRNA transfection agents. These data suggest that RNTs has the potential to be both an efficient and biocompatible gene delivery platform.

Biomedical devices are used widely in many different parts of the body for applications such as orthopedic implants, pacemakers, cardiovascular stents, neural prosthetics and drug delivery systems. Often complications arise from these biomedical devices due to inflammation and/or foreign-body reaction. To minimize bacteria adhesion and foreign body reaction, an anti-fouling material is often coated onto biomedical devices before their implantation.

We have synthesized a series of lysine-containing acrylate-based hydrogels for anti-fouling applications. These novel zwitter-ionic materials were designed to be easily applied as a coating; they were stimuli-responsive and formed hydrogels rapidly upon exposure to ultraviolet light. The hydrogels were tested in vitro and have demonstrated very good resistance towards protein adsorption, bacteria adhesion and cell adhesion, illustrating their potential as anti-fouling coatings for biomedical devices. They also showed excellent cell viability and low hemolysis results, indicating that they are biocompatible. They were implanted in mice for 2 months, and did not show any foreign body reaction. The in vitro and in vivo results successfully demonstrated the potential of the novel hydrogel system as an anti-fouling material.

Gellan gum, a negatively charged natural polysaccharide and common food additive, has gained significant interest for tissue engineering. Gellan forms hydrogels by undergoing a random coil to helix transition upon cooling below 45°C. In the presence of cations, aggregation of the helices is strengthened, leading to stronger gels. The viscosity of low concentration gellan hydrogels (below 2 wt%) has been studied under low shear rates (less than 10 s^-1) as a function of temperature (Matricardi P, 2009). Mechanical properties of gellan hydrogels over a broad range of polymer concentrations and shear rates, however, have not yet been characterized. We have previously shown that gellan hydrogels hold promise for drug delivery (Shukla, S. and Shukla, A., 2016, submitted), leading to sustained release behavior of vancomycin, an encapsulated therapeutic, by varying gellan and cation concentration, which also affects hydrogel swelling. We propose that drug release is a function of increasing ion and polymer concentrations which directly enhance gel swelling and entanglement. Motivated by these findings, in this work, we investigated gellan drug release kinetics and related this to the viscoelastic properties of the hydrogel over a large range of polymer and ion concentrations.
Vancomycin (0.6% w/v) and CaCl₂ (1, 3, 7, or 10 mM) loaded gellan (1, 2, 3, or 4% w/v) hydrogels were developed and UV-visible spectrophotometry was used to assess vancomycin release at 37°C. Increasing polymer concentration from 1% to 4% w/v increased cumulative drug release by 40%, over 6 days. Within each polymer concentration, cation concentration also affected drug release. However, we saw that polymer concentration has a greater effect on drug release than ion concentrations. To better understand the influence of viscoelastic properties on these release kinetics, rheological oscillation studies of hydrogels were conducted (shear rate: 10-600 s^-1). Increasing the polymer and ion concentration from 1% to 4% w/v and 1 mM to 10 mM, respectively, increased the storage (G’) and loss (G”) moduli. Moduli difference of 4 orders of magnitude from ointment (1% w/v gellan; 1 mM CaCl₂) to sheet (4% w/v gellan; 10 mM CaCl₂) demonstrated increased gel strength and crosslinking (chain entanglement). We determined that hydrogels with similar G’ and G’’, but different polymer and ion concentrations, led to similar drug release kinetics. For example, 10 mM CaCl₂ and 1% w/v gellan hydrogels exhibited similar G’ and G’’ to 1 mM CaCl₂ and 4% w/v gellan hydrogels, and both had similar drug release profiles. These results suggest that the viscoelastic properties of the hydrogel are directly related to the drug release kinetics. This work explains the relationship of gellan hydrogel formulation to its mechanical properties and release kinetics, which can ultimately be used to improve hydrogel design for therapeutic applications.

Biotin and avidin binding is one of the strongest known non-covalent bonds in nature. With a variety of biotinylation reagents targeting different biomolecules, various functions can be imparted onto biomaterials through the avidin-biotin linkage. This feature makes biotin and avidin binding a very useful tool for the biofunctionalization of drug delivery systems such as polymeric micelles. In this study, self-assembled hydrophobically modified glycol chitosan (HGC) micellar nanoparticles were functionalized with a novel avidin and biotin binding strategy to improve their target-selective ability as an anti-cancer drug delivery system. Briefly, HGC was biotinylated at the primary amine groups on the chitosan backbone before being linked to a green fluorescent model biomolecule, biotin-4-fluorescein (B4F), via the avidin-biotin interaction. Cyanine 5.5 was also conjugated to HGC to aid in the visualization of delivered nanoparticles. The hydrodynamic diameter of biotinylated and avidinylated HGC (BHGCA-B4F) nanoparticles was 93.68±1.1 nm and the surface charge was 0.9±0.1 mV. Confocal microscopy and N-SIM (super-resolution microscopy) showed that at a delivered concentration of 0.1 mg/mL, BHGCA-B4F nanoparticles were distributed widely throughout the cytoplasm of 4T1 mouse breast cancer cells after 2 hours of exposure without significant cytotoxicity. The co-localization of Cy5.5 and FTIC channels confirmed that the avidin-biotin linkage between HGC and B4F was successful and remained stable in the intracellular environment. Taken together, our study demonstrated that avidin and biotin functionalized HGC nanoparticles have a great potential as a cancer-targeting drug delivery system.

Live cells are the basic working units in the biological tissue, performing different functions as nature’s microreactors. Assembly of sub-compartmentalized microreactors has become an important approach to mimic cells due to its advantages on the structure similarity as cells, easy encapsulation of different subunits with multiple cargos, and the controllable activity trigger. With the aim to make artificial hepatocytes, we designed different sized microreactors with entrapped enzyme loaded liposomal subunits using droplet microfluidic or the layer-by-layer assembling techniques. First, the synthetic partner particles or capsules were co-cultured with biological hepatocytes and successfully incorporated into the growing cell culture, forming bionic tissues with artificial and biological components. The surfaces of the particles or capsules coated with different polymers facilitated a beneficial biological response, i.e., the integration of the artificial and biological hepatocytes in a co-cultured tissue sheet. Further, the biological hepatocytes proliferation in the bionic tissue was assessed by microscope visualization and cells’ double-stranded DNA (dsDNA) quantification. Furthermore, detoxification, the key function of liver cells, was performed by loading the enzyme catalase for removing toxic chemical hydrogen peroxide (H₂O₂) into the liposomal subunits of the artificial hepatocytes, and the viability of hepatocytes in the bionic tissue was improved when the microreactors degraded externally added hydrogen peroxide. These findings are a major step towards the assembly of bionic tissue – a combination of biological and synthetics entities.

Magnetic resonance imaging (MRI) has been a widely used clinically diagnostic tool over decades, where the relaxation of water protons in the object is used to extract morphological/anatomical information with high resolution and unlimited tissue penetration. Contrast agents (CAs) shorten the relaxation time of water protons to enhance contrast and gadolinium (Gd³⁺)-complexes are now one of the most powerful class of CAs applied in both fundamental research and clinical applications. While theoretical model predicts that relaxivity as high as 80-100 mM^-1s^-1 per Gd³⁺ at 1.5 T can be achieved, commercial CAs usually have a low relaxivity around 3-5 mM^-1s^-1. Here we show that using by controlling the size and surface coating of Gd³⁺-based inorganic nanocrystals, we can push the relaxivity approaching the theoretic limit predicted by the model. Also, with increased relaxivity per Gd³⁺, it is possible to address the safety concern of injected CAs due to much less applied dosage. Furthermore, the limit of accumulating large local concentration of CAs to observe contrast can also be overcome by our CAs with high relaxivity. Therefore, this type of Gd³⁺-based high performance MRI CAs is both fundamentally and clinically important.

The human body consists of multiple kinds of cells. Correct identification and selection of cell type from a mixed population of different cells is of substantial importance in many aspects such as cancer therapy, tissue engineering, disease modeling and stem cell differentiation. Antibody based methods is up to now the most effective non-invasive method for cell type identification. However, besides of batch difference and cost issues, the antibody based methods also have a critical defect that is not all cells have unique surface marker. Here we propose a novel cell-type recognizing circuit, combining synthetic RNA switch, surface enzyme and spatial-temporal aggregation of synthetic peptides. Recent studies have revealed that each type of human cell has a unique profile of microRNA. Based on this fact, we are able to design RNA switch, of which the translation is responsive to target cell specific microRNA. The differential expression of microRNA between target cells and non-target cells results in different translation yield of the surface enzyme encoded on the RNA switch. We then apply synthetic peptide that contains a self-assembly motif and enzyme substrate site. Spatial-temporal aggregation of the peptide forms specifically on the cells that have high amount of the surface enzyme to distinguish them from other types of cells. As a proof of concept, we construct a miR-208a responsive RNA switch that encoded an ecto-alkaline phosphatase and apply it to a mixed culture of differentiated cells derived from iPSCs. By applying a peptide that forms toxic aggregates upon dephosphorylation, the miR-208a positive cardiomyocyte survive and non-cardiomyocyte cells are selectively removed. Such circuits as many advantages, including the ability to target any type of cells; involving no exogenous gene or protein; tunable at multiple levels. Moreover, by simply designing the synthetic peptide, the targeted type of cell can be visualized, purified from other cells, or selectively removed by engineering of the synthetic peptide. We believe our novel circuit system that based purely on biomolecules, has substantial potential to serve as a new tool for cell type recognition for laboratory and clinical applications.

The performance of many medical and engineering applications are highly dependent on the surface attachment and aggregation of bacteria. For instance, the accumulation of exopolymeric matrix and biofilm formation can reduce the efficacy of antibiotic treatments, and are generally undesired on medical implants and instruments. On the other hand, the efficiency of microbial fuel cells depends directly on the ability of bacterial cells to proliferate and establish tight electrical contacts with the electrodes through surface attachment. In recent years, nanostructured surfaces have been shown to elicit a wide range of prokaryotic responses that were not known previously, thus making such surfaces promising candidates for controlling bacterial behavior. However, there has been a lack of comprehensive theoretical frameworks that describe how bacterial activities are altered by the changes in its physicochemical and biological environments brought about by nanostructured surfaces.

To understand this, we have fabricated nanogratings with dimensions that were varied systematically from subcellular to cellular length scales. The adhesion, alignment and aggregation of the gram-negative bacteria, Pseudomonas aeruginosa, on these nanogratings were then examined and quantified by means of scanning electron microscopy and epifluorescence microscopy. Compared to a flat surface, nanogratings were found to increase alignment of the bacterial cells by up to 850%, while reducing attachment and aggregation levels by a maximum of 83% and 84% respectively. The improvement in alignment was attributed to the relative ease of attachment that bacteria aligned with the nanogratings have over non-aligned bacteria, as our analysis revealed that passive physicochemical interaction forces alone can bring aligned bacteria into contact with the nanogratings, whereas active use of cellular appendages was required for adhesion of non-aligned bacteria. In addition, the fall in aggregation levels was found to be due to the entrenchment of aligned bacteria within the nanogratings by capillary forces, which physically isolated the bacteria and prevented them from enhancing the adhesion of non-aligned cells and forming micro-colonies with them. Lastly, bacterial attachment on nanogratings were shown to be highly dependent on the physicochemical environment, which can be modified by both biological and non-biological factors, and the overall effect is such that attachment is the greatest on nanogratings with physical dimensions resembling those of a bacterial cell, possibly indicating an important role that physicochemical forces play in assisting bacteria form tightly packed aggregates. The insights derived in this study are expected to be useful for the design of advanced surfaces that can bring about specific bacterial responses.

Reactive oxygen species (ROS) are a collective term of highly reactive chemical species and radicals, including hydrogen peroxide, superoxide anion and hydroxyl radical. Compared to normal cells, cancer cells are under oxidative stress associated with the elevated level of ROS and are more vulnerable to oxidative stress induced by ROS generating agents. Thus, manipulation of the ROS level provides a logical approach to kill cancer cells preferentially, without toxicity to normal cells. Cinnamaldehyde, a major active compound of cinnamon, exerts anticancer activity by generating ROS. Despite its ROS-mediated anticancer activities and excellent toxicity profiles, the clinical applications of cinnamaldehyde are limited by the low bioavailability and less therapeutic efficacy than commercial anticancer drugs. In this regard, we synthesized polymeric prodrugs of cinnamaldehyde as a platform of oxidative stress amplifying anticancer nanotherapeutics.
We developed dual pH-sensitive PBCAE as a polymeric prodrug of cinnamaldehyde which incorporates ROS-generating cinnamaldehyde in its backbone via acid-cleavable acetal linkages. PBCAE was designed to self-assemble to form micelles and encapsulate ZnPP which suppresses antioxidant hemeoxygenase-1 (HO-1). Proof-of-concept studies revealed that ZnPP-encapsulating PBCAE micelles suppressed HO-1 to make cancer cells more vulnerable to ROS, leading to enhanced apoptotic cell death and suppressed the tumor growth in human cancer xenograft mouse models. We also developed Fenton reaction-performing polymer (PolyCAFe) micelles as a new class of ROS-manipulating anticancer therapeutic agents. PolyCAFe incorporates H₂O₂-generating cinnamaldehyde and iron-containing compounds in its backbone and self-assembles to form micelles that serve as Nano-Fenton reactors. PolyCAFe micelles generate hydroxyl radical by performing Fenton reaction to kill cancer cells preferentially. When intravenously injected, PolyCAFe micelles could accumulate in tumors preferentially to remarkably suppress tumor growth, without toxicity to normal tissues. Taken together, we anticipate that ROS-generating polymeric prodrug of cinnamaldehyde has great potential for anticancer therapy.

Excessive and unregulated production of reactive oxygen species (ROS) such as hydrogen peroxide (H₂O₂), superoxide and hydroxyl radical leads to oxidative stress, causing inflammation and cellular damages and death. H₂O₂ is considered as the most stable and abundant ROS and H₂O₂-mediated oxidative stress is a key mediator of cellular and tissue damages during ischemia/reperfusion (I/R) injury and acute liver failure. Therefore, H₂O₂ could hold tremendous potential as a diagnostic biomarker and therapeutic target for oxidative stress-associated inflammatory conditions such as I/R injury. Vanillin is the major component of vanilla and has anti-inflammatory activity to suppress the expression of various pro-inflammatory cytokines. However, its clinical applications are limited by rapid clearance from blood circulation. In this study, we developed a polymeric prodrug of vanillin, poly(vanillin oxalate)(PVO), in which vanillin is covalently incorporated in its backbone and can be released during its acid-triggered hydrolytic degradation. In addition, PVO possesses peroxalate ester linkages which undergo rapid H₂O₂-triggered oxidation to generate CO₂. Here, we report potential of PVO nanoparticles as a nanotheranostic agent for H₂O₂-associated diseases. PVO nanoparticles generate CO₂ through H₂O₂-triggered oxidation of peroxalate esters and release vanillin, which exerts antioxidant and anti-inflammatory activities. PVO nanoparticles intravenously administrated remarkably enhanced the ultrasound signal in the site of hepatic I/R injury and also effectively suppressed the liver damages by inhibiting inflammation and apoptosis. In addition, when desired, PVO nanoparticles could serve as a drug delivery system. To our best understanding, H₂O₂-responsive PVO is the first platform which generates bubbles to serve as ultrasound imaging agents and also exerts therapeutic activities. We therefore anticipate that H₂O₂-triggered bubble-generating antioxidant PVO nanoparticles have great potential for ultrasound imaging and therapy of various H₂O₂-associated diseases.

The overuse of antibiotics plays a major role in the emergence and spread of multidrug-resistant bacteria. A molecularly targeted, specific treatment regimen that acts in narrow spectrum would provide a great advantage by reducing the selective pressure in bacterial growth. Herein, we introduce a gene therapeutic approach based on nonviral delivery of genome editing material for treatment of the multidrug-resistant infections and preventing the spread of these pathogens. We apply the CRISPR-Cas9 system, which has been recognized as an innovative tool for highly specific and efficient genome engineering in different organisms, as the therapeutic cargo. Since most gene editing strategies using CRISPR-Cas9 have been based on viral vectors, and thus limited in applicability for therapeutic purposes, we have developed a nonviral system utilizing a nanocomplex of chemically modified Cas9 endonuclease and single-guide RNA. We show that the CRISPR nanocomplex targeting mecA - the gene involved in methicillin resistance - can be efficiently delivered into Methicillin-resistant Staphylococcus aureus (MRSA). The CRISPR nanocomplex showed sufficient functional activity in genome editing which was comparable to native Cas9. The present study shows the potential applicability of the CRISPR nanocomplex in the clinic as a target specific antimicrobial and ultimately contributes to global health.

Polycaprolactone (PCL) is an ideal biodegradable biomaterial for biomedical applications owing to its hydrolytic ester bonds. Recent studies have shown a surge in the ongoing research for the application of PCL in tissue regeneration, drug delivery and as an implant material. The inertness of PCL however limits its application and it is often required to conjugate the material with other chemical entities to impart functionality to it. In our present work, we report the synthesis of a conjugated PCL monomer. The monomer is further polymerized to form PCL containing high density of reactive sites for cross-linking and post modifications. 2-cyclohexen-1-one is reacted with 3-butenylmagnesium bromide in the presence of Grignard reagent to yield 4-(3-butenyl) cyclohexanone. This resulting cyclic ketone is subjected to Baeyer-Villiger reaction using triple salt of potassium to yield the lactone monomer. The monomers are polymerized to form PCL using benzyl alcohol as initiator and stannous octoate as a catalyst. The synthesized monomer and the polymer is characterized and confirmed using nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy. The number average molecular weight (Mn) is calculated using the end group analysis from the NMR spectra and it is found to be 3760 g/mol. Mn is further confirmed using gel permeation chromatography (GPC) and matrix assisted laser desorption/ionization – time of flight analysis. The polydispersity index measured by GPC curve is found to be 1.3. Thermal characterization of the synthesised PCL is done using thermogravimetric analysis and differential scanning calorimetry. Since biodegradability is an important aspect for a biomaterial, invitro degradation is tested under phosphate buffer saline solution. The work described above is an excellent approach to overcome the limitations of widely used inert PCL polymer. The presence of vinyl group on the polymer will facilitate crosslinking and will provide binding sites for other chemical groups which will diversify the application of PCL in biomedical industry.

Three arm junction RNA nanostructures (Y-RNA) can provide dual roles of structural function and the biological function such as RNA interference (RNAi) by inserting siRNA sequences (anti-GFP, RFP, and BFP) into the each arm of Y-RNA. Through sequence and length optimization of the arm of Y-RNA, Y-RNA is carefully designed to be Dicer substrate for enhanced RNAi potency as well as prolonged effect. Interestingly, the Dicer processing and loading of the Y-RNA into the RNA Induced Silencing Complex (RISC) was highly dependent on the physical structure and sequence design of the three-arm junction. In addition, we enzymatically prepared Dicer substrate Y-RNA with a large scale using rolling circle transcription (RCT) and site-specific cleavage. Depend on cleavage site of helper, various Y-RNA can be produced from a single DNA template, inducing controlled RNAi effect. Our study can provide clarified RNAi nanostructures for programmable as well as simultaneous gene silencing in vitro.

The antibacterial properties are useful to restrain inflammatory response caused by bacterial infection after implantation. Hydroxyapatite (HAp) ceramics including silver, which are substituted in calcium sites of HAp, have been investigated for expressing antibacterial properties. However, it has short coming such as rapid release of silver ions, low loading amounts of silver ions in the ceramics, and poor antibacterial property. On the other hand, the composites of HAp and silver nano-dots, silver oxide or silver phosphate were prepared. There are still some disadvantage for sintered bodies; 1) silver nano-dots grow large, and are not homogenously distributed, 2) silver nano-dots melt and remove, and 3) silver phosphate and silver oxide formed exhibit higher solubility than silver. In this study, the distribution of silver nano-dots in HAp sintered microparticles were controlled at grain boundary by using a modified silver mirror reaction and the release profiles of silver ions from the microparticles were investigated. HAp suspension was synthesized by a wet method as starting substances of phosphoric acid and calcium hydroxide suspension. Then, the HAp suspension was supplied to a spray drier at the outlet temperature of 60°C to fabricate spherical porous microparticles with approximately 5 mm in average diameter. The microparticles adsorbed formaldehyde by a vapor deposition method at 37°C were soaked in an ammoniacal silver nitrate solution to form silver nano-dots inside the microparticles (Ag-HAp_f). As references, the particle with no formaldehyde were dispersed and stirred in a silver nitrate solution (Ag-HAp_r). The suspensions were centrifuged, washed with distilled water, and dried in vacuum at 60°C. The HAp microparticles including silver nano-dots were then sintered in static air at 1200°C for 30 min. From XRD patterns and inductively coupled plasma analysis of the as-prepared samples, Ag-HAp_f was composed of metal silver at 11.3 wt% and HAp. On the other hand, Ag-HAp_r was composed of silver phosphate and HAp, and the silver content was 10.4 wt%. After sintering at 1200°C, the crystalline phases for Ag-HAp_f were not changed, but those for Ag-HAp_r were to be metal silver, HAp and tricalcium phosphate. The silver contents of both the Ag-HAp microparticles were 6.3 wt%. In the SEM observations, the silver nano-dots in Ag-HAp_f were distributed inside the microparticles; in contrast, silver microparticles on the surface of Ag-HAp_r were observed. In the cross-sectional reflection electron microscopic observations, the silver nano-dots were rarely inside Ag-HAp_r; in contrast, the silver nano-dots with 0.20 ± 0.07 mm were homogeneously distributed in the sintered Ag-HAp_f. The release profiles of silver in phosphate buffer saline were different; the elution amount of silver from Ag-HAp_f was one-thirteenth of that from Ag-HAp_r. These results suggest that Ag-HAp_f will be suitable for a long-term antibacterial material.

Multifunctional bicompartmentalized nanoparticles (BNPs) composed of two distinct compartments with opposite charges and stimuli-responsiveness have recently received increasing attention because of asymmetric surface functionalities and different physicochemical properties at each compartment. In this study, we report that oppositely charged BNPs as electric dipolar nanoparticles exhibited their colloidal self-assembly into the well-organized superparticular structures via noncovalent interactions, representing new collective properties that are totally different from those of individual BNPs. Additionally, they showed different drug release kinetics from each charged compartment in response to charge-charge interaction as well as external stimuli. Oppositely charged, thermally responsive N-isopropylacrylamide (NIPAM) copolymers with hydrophobic moiety were separately synthesized at different molar ratios via free radical polymerization, and showed unique phase transition behaviors as a function of temperature, pH, and hydrophobic moiety. Stimuli-responsive BNPs with oppositely charged compartments were prepared via electrohydrodynamic (EHD) co-jetting and showed reversible swollen or collapsed nanostructures triggered by temperature under physiological conditions. Moreover, they self-assembled into supra-colloidal structures via electrostatic interaction between oppositely charged compartments of the BNPs, and degree of self-assembly was controlled by charge density of NIPAM copolymers at each compartment, ionic strength and temperature under aqueous conditions. Furthermore, in order to show that oppositely charged BNPs exhibit different drug release kinetics from each charged compartment in response to charge-charge interaction as well as external stimuli, these bovine serum albumin and lysozyme as oppositely charged biomacromolecules were hydrophobically modified by ion paring between charged proteins and polysaccharide-based polymers, followed by homogeneous encapsulation within each compartment of the BNPs via EHD co-jetting. Two separate proteins loaded within the BNPs were controlled released at different kinetics based on electrostatic interaction and thermal stimulus. In conclusion, this work has great potential for industrial and biomedical applications including ion-sensitive gels, colloidal crystals for switchable display and advanced drug delivery carriers for decoupled drug release kinetics based on their anisotropic characteristics.

Magnetic bioseparation is an important area of biotechnology. Various techniques are becoming increasingly important with a wide range of possible applications in bioscience research. Magnetic micro- or nanospheres can be functionalized with appropriate ligands, such as antibodies or proteins, with a high affinity to the target which can be cells, bacteria or DNA/RNA.

In order to realize magnets with efficient separation capabilities, it is important to have a strong force F acting on the magnetic bodies, given by the following equation:

F = V Δχ B gradB/µ_{0 .}

Here, V is the volume, Δχ is the difference in the susceptibility of the magnetic particles and the surroundings,

B gradB is the product of the magnetic field and field gradient and µ₀ is the vacuum permeability.

Many permanent magnets on the market have very large magnetic fields, but weak field gradients. GIAMAG magnets have unique and patented designs that produces both very large magnetic fields and high field gradients, resulting in the most forceful magnetic separation available on the market [1,2,3].

Acknowledgments

The project has been funded in part by the Research Council of Norway and the Institute for Energy Technology.

References

[1] www.giamag.com

[2] E. I. Il'yashenko, V. A. Glebov, A. V. Glebov, A. T. Skjeltorp and T. H. Johansen, Permanent magnet systems with strong stray magnetic fields and very high gradients for material separation, Physica status solidi (a), Volume 203, Issue 7, pages 1556–1560, 2006.

[3 Patent: E. I. Il'yashenko, V. A. Glebov, A. V. Glebov, A. T. Skjeltorp and T. H. Johansen, Method for forming a high-gradient magnetic field and a substance separation device based thereon
http://www.google.com/patents/CA2595721A1?hl=no&cl=en

Because they exhibit important biological functions, from unfolding proteins to control cell fates, aggregates of small molecules are able to serve as functional molecular entities in cellular environments. However, the instability to precisely control their production has hampered the understanding and exploration of their biological activity. In this work, we report the well-known ligand-receptor interactions between vancomycin and D-Ala-D-Ala catalyze the aggregation of D-Ala-D-Ala containing small peptide derivatives in water, the resulting aggregates largely adhere to the cell surface to induce the cell death. Meanwhile, mutation of D-Ala-D-Ala to L-Ala-L-Ala or removal of the aromatic group in the derivative result in innocuous compounds, confirming that the aromatic–aromatic and ligand–receptor interactions are essential for the formation and corresponding cytotoxicity of the aggregates. Furthermore, the replacement of Fmoc to pyrene group in the D-Ala-D-Ala containing peptide caused the dramatically different cellular responses. The peptide of Pyrene-D-Ala-D-Ala generates cytotoxic nanofibrils that caused the death of neuron cells (i.e., PC 12). The addition of Vancomycin effectively converts the nanofibrils to nanoparticles that are innocuous to cells. Preliminary mechanistic study reveals that, in contrast to the fibrils, the particles promote the expression of TNFR2, a cell survival signal, and decrease the expression of TNFR1 and DR5, two extrinsic cell death receptors. As the first example of ligand-receptor interaction to modulate the cytotoxicity of nanoscale assemblies of small molecules, this work illustrate an unique approach to use supramolecular interaction to control the morphology of supramolecular assemblies for tuning their biological functions.

Curcumin, a sunny yellow pigment, is the main dynamic ingredient of turmeric; an ancient spice well-known for its medicinal applications. It is known to have antioxidant, anti-inflammatory, chemo-preventive and therapeutic properties. Bioavailability is the most critical requirement for harnessing the biological activity of curcumin for therapeutic applications in human health care. Mostly, the oral bioavailability of curcumin is very slight because of its low intestinal absorption and rapid metabolism. Herein we report that co-sonication of curcumin with acidic sophorolipid in aqueous solution leads to enhancement of curcumin bioavailability through size reduction down micron to nanoscale, encapsulation and subsequently its aqueous environment stability. The interaction between the two is studied in details and discussed based on optical absorption (UV-Vis), photoluminescence (PL), Zeta potential, dynamic light scattering (DLS), TEM, FE-SEM, X-ray diffraction and Infrared spectroscopy measurements (FTIR). Self-assembled Complex (SL(A)+Cur) has shown biocompatible behaviour towards human normal cell lines (HEK-293). Anticancer activity of SL(A)+Cur complex performed on two cancer cell line (MCF-7 and MDA-MB-231). The cytotoxicity effects of curcumin on breast cancer cell lines, MCF-7 and MDA-MB-231, are revealed to be significantly improved by the formation of its complex with sophorolipid. The comparative cytotoxicity of curcumin with its SL(A) complex is increase probably due to the presence of glucose moiety, a synergistic effect. It has been clearly established that the self-assembly of Curcumin with SL(A) significantly reduced its therapeutic index, reflecting its enhanced bioavailability. The results clearly suggest that sophorolipid based self-assembly, which solubilize and nano-encapsulate curcumin with lipid digestion, have great potential for curcumin cell membrane delivery. This study emphasizes that solubilisation of curcumin by nano-encapsulation is an effective aspect of designing drug delivery systems.

We report on the preparation of a new type of multifunctional biohybrid material using binary crystals from oppositely charged protein containers for the precise arrangement of metal oxide nanoparticles into highly ordered superlattices. The engineered protein containers form crystalline assemblies with a tetragonal lattice as shown by X-ray crystallography to high resolution. The structure type can be best described as CuAu lattice with a sheet-like arrangement of like-charged particles. Moreover, the cavities of the protein containers were used for the size-constrained synthesis of metal oxide nanoparticles. By assembling oppositely charged protein containers with nanoparticle cargo, highly ordered nanoparticle superlattices with variable nanoparticle compositions could be obtained as free-standing crystals, with up to a few hundred micrometers in size. The crystals could be readily fixated by glutaraldehyde crosslinking and were characterized using SAXS, SEM and EDX. As confirmed by SAXS analysis the crystal lattice is solely determined by the protein shell which overwrites any imperfections of its nanoparticle cargo. By self-assembly of oppositely charged protein containers with nanoparticle cargo in this way, biohybrid structures are generated with potential application in catalysis, bioelectronics and biomedical use.

In nature, most organisms emerge initially in a soft/compliant state and go through a stiffening process to form various hard/stiff bio-components. For example, the jaw of the marine worms or cuticles of mussel byssal thread consist of mostly protein with coordinated metal ions. This organic material processing from an initially soft/compliant hydrated state towards a hard/stiff functional material follows routes that are different from biomineralization oftentimes involving controlled material dehydration. With the growing need for sustainable material processing, the interest in understanding the underlying physical-chemical mechanisms that control the change in properties during such biological material transitions has increased. Herein, we focus on characterizing the dehydration dynamics of a simple bio-inspired synthetic model material system. In particular, we study the changes in mechanical properties between the soft (hydrated) state and hard (dehydrated) state of mussel-inspired catechol-PEG networks crosslinked via coordination bonds. We investigate the underlying relation between temporal evolution of mechanical stiffness and crosslinking behavior and discuss the unique role of metal-coordinate bonds in the stiffening process. This study will provide insights on bio-inspired processing from soft to hard materials as well as inspire new ideas on sustainable material processing.

Material science has shown a new avenue of contribution in the field of immune-bioengineering offering smart and tunable drug delivery platforms. Conventionally, the immune system used to instruct and dictate the fate of the therapeutic intervention, however today the advances in nanomaterial based applications are themselves used to control the immune system behavior. In cancer, STAT3 pathway (Signal transducer and activator of transcription 3) is highly expressed in tumor cells as well as (Dendritic Cells) DCs leading to suppression of DCs surface receptors. A promising approach that can reverse the suppressed status of DCs is STAT3 inhibition. Despite the potent STAT3 inhibitory effect of the anthraquinone derivatives, there are some limitations e.g. poor water solubility, nonspecific side effects and lack of sustained release. Novel platforms like nano-carriers represent a promising approach of drug delivery systems that will enhance the efficacy of the therapeutic agent and help overcome the existing limitations. In this study we have used anthraquinone derivative to inhibit STAT3 in a sustained fashion using pegylated nano-liposomes. This anthraquinone based STAT3 inhibitor is used for the first time in cancer nano-immunotherapy context. Nano-liposomes act as a biocompatible and biodegradable lipid based carrier that is approved by FDA. These lipid based nanoparticles can provide a platform for safe and sustained delivery to DCs, paving the way towards efficient cancer nano-immunotherapy. PEG chain is cross linked to the lipids to elicit a lot of useful properties, as it is biocompatible, soluble and exert low antigenicity with a good excretion profile. To our knowledge, this is the first time liposomes are used as a carrier for anthraquinone based STAT3 inhibitor. Pegylated nano-liposomes were synthesized loaded with modified form of the STAT3 inhibitor, the modification of this STAT3 inhibitor entails chemical conjugation with cholesterol in order to maximize the physical stability and the loading efficiency reaching 85%. The product was characterized by mass spectrometry confirming that the parent peak is corresponding to our conjugate. Cryo-TEM revealed the formation of predominant unilamillar structures. The NPs were added to the immunosuppressed DCs and maturation status was assessed using flow cytometry. Expression of CD86, MHCII and CD80 were evaluated. No significant change was observed in case of CD80. Slight increase was observed in case of CD86. However, surprisingly there was a dramatic increase in MHCII. These results demonstrate the potential of the novel Nano-particulate anthraquinone based STAT3 inhibitor in reversing the immunosuppressed status of DCs in tumor microenvironment and its immune-modulatory role for the first time.

The blood-brain barrier (BBB) is a critical limitation on the efficacy of chemotherapeutic treatments for cancers such as glioblastoma. The continuous capillaries of the brain, in addition to high intracranial pressure, allows for the resistance of foreign matter such as viruses, bacteria and drug therapies to pass readily by diffusion. Polymer based nanoparticles (NPs) are useful vehicles for drug therapy across the BBB because of the stability of the drug and controlled release of the drug over time. The nanoparticles are able to cross the BBB via receptor-mediated endocytosis or transcytosis across the tight junctions of the endothelial cells and into the brain. Transferrin receptors are unique to brain capillary endothelial cells (BCECs). Binding of transferrin-peptide-conjugated NPs to transferrin receptors in the brain allows the NP to “target” cells and cross the BBB by transcytosis. Surface modification of NPs using covalent conjugation of polyethylene-glycol coating, or PEGylation, prolongs in vivo pharmacokinetics by delaying excretion by the kidneys and extending drug plasma life.
Temozolomide, or TMZ, is an alkylating agent currently used to treat glioblastoma by covalently attaching alkyl groups to substrate DNA bases, causing point mutations or “lesions” in cell DNA, therefore disrupting the cell cycle. Cetiranib is a pan-VEGFR tyrosine kinase inhibitor which inhibits vascular endothelial growth factors (VEGFR) 1, 2, and 3. Cetiranib has proven successful in combination with conventional chemotherapy in a phase II studies of metastatic cervical cancer and monotherapy of glioblastoma multiforme.
The use of a traditional chemotherapy drug used to treat glioblastoma, TMZ, in combination with a repurposed drug, Cetiranib, prepared as a nanoparticle therapy will provide the medical field with new research on the possible ways to treat glioblastoma. TMZ-Cetiranib-loaded NPs have the potential to target glioblastoma cells in cell cycle and anti-angiogenesis mechanisms which may allow for longer progression free survival in patients and fewer systemic side effects due to the nanoparticle drug delivery. The specific aims of this research are to synthesize and characterize 80-200 nm PEGylated-Tf-conjugated-TMZ-Cetiranib PLGA NPs and assess the LD50 and cytotoxicity of the conjugated NPs through MTT/MTS assay using the U87 MG cell line. Testing of the cell line with free drug will be done to assess efficacy of NPs synthesized.
If the specific aim of double-loaded drug NPs is not obtainable, the single loaded drug NPs will be prepared and further PEGylated and conjugated with Tf, then tested in cell lines and compared to the free drug. The major goal of this research is to investigate a new combination of chemotherapy drugs in NP formulation to provide for a more effective targeted cell therapy in glioblastoma patients.

The heterogeneous composition of Janus particle leads to its unique advantages as drug carrier in terms of segregation of the active payload and simultaneous delivery of distinctively different drugs. However, the-state-of-the-art synthesis methods requires multiple steps and results limited yield. We recently developed one-step synthesis method of biodegradable Janus particle based on emulsion evaporation. The composite particle is made of poly(lactic-co-glycolic) acid (PLGA) and polycaprolactone (PCL), with an average diameter of 100 mm. It has been reported that Janus particle structure changed after addition of drug. However, glibenclamide (GLN) loaded Janus particle were successfully synthesized using our method. The weight ratio of PLGA/PCL polymer was varied systematically to obtain the optimum polymer phase separation for Janus structure. During our development, it was found that the charge carried by the drug played a key role in altering polymer interaction in emulsion, degree of engulfment and particle structure. Such change enabled a switching between anisotropic structure and core-shell structure. This finding was validated by replacing the drug with charged and uncharged agents. Our finding enabled us to fabricate both Janus particle and core-shell particle loaded with 10% GLN with 100% encapsulating efficiency. Janus particle showed zero-order release of GLN with 48.3% cumulative release on day 30. Its release profile displayed characteristics peaks from both PLGA and PCL microparticle loaded with equivalent amount of GLN. In comparison to core-shell microparticles, Janus particle showed better inhibition on burst release. In summary, our results showcased the success of fabricating drug loaded biodegradable Janus particle using emulsion method. It also demonstrated that the ability of Janus particle in control releasing the model drug GLN over a month with lower burst release. With the simple equipment and our one-step fabrication method, the potential of synthesis drug loaded Janus particle in large quantity is promising for biomedical application.

Due to the recent progress in the field of medicine and nanobiotechnology, a huge interest have been shown to antibacterial coatings. Here, we present an innovative method, based on Liquid Phase Pulsed Laser Ablation (LP-PLA) and Atmospheric Plasma Polymerization (APP) to elaborate antibacterial hybrid thin films^[[1]]. This new generation of hybrid coatings is based on the synergetic effect of bacteriostatic and bactericidal properties combining plasma polymer superhydrophobic surfaces and antibacterial silver nanoparticles.
First, the elaboration of superhydrophobic coatings from plasma polymerization at atmospheric pressure (PP-AP) of dodecyl acrylate (DOCA) and/or perfluorodecyl acrylate (PFDA) are presented. Besides physical and chemical characterizations of the surface of the plasma coating by XPS and AFM analysis, the superhydrophobic properties are determined by water contact angle measurements. Very interestingly, adjusting the ratio of the two monomers permits to finely control the wetting behaviour, from a Wenzel to a Cassie-Baxter wetting regime.
Then, attention is carried on the production of silver nanoparticles (Ag NPs), known for their high and long term bactericidal activity, by a promising strategy consisting on the laser beam ablation (LP-PLA) of a silver metallic target directly immerged in plasma polymer precursors (DOCA or PFDA). Based on AAS, Raman, UV-Visible and TEM analysis, the complex mechanisms of silver ablation in monomeric precursor has been elucidated and a huge morphologic and compositional control on the produced bactericidal compounds have been achieved allowing to select agents with a desired activity.
Finally, hybrid multifunctional coatings owning anti-biofouling and bactericidal ability are elaborated. It consists in plasma polymerization of the aforementioned silver colloidal suspensions in organic precursors. Besides the characterizations of these new plasma polymer coatings, few examples of antibacterial properties are shown by comparing the results obtained with silver-free or silver-containing precursors with different wetting regimes. The achievement of such a control allows an efficient choice between silver releasing and superhydrophobic repulsion rising to a longer and broader-spectrum antibacterial action.



[[1]] Petersen J., Becker C. and Mertz G. (2014). Hybrid coating and method to obtain such coating, Google Patents

Magnetic nanoparticles (MNPs) have found a wide variety of uses in vivo such as magnetic resonance imaging, drug delivery, cancer hyperthermia therapy and magnetophoresis [1]. In order to enhance the biomedical value of these MNPs they are often functionalized with ligands such as peptides, antibodies and other small molecules [2] which can actively target certain cells.

Condensing the catechol 3,4-dihydroxybenzhydrazide with aldehydes bearing recognition groups that target cell surface receptors, followed by coating the surface of MNPs with the conjugates, should allow MNPs to bind specific cell types. Previous work has shown that biotin-catechol hydrazones are effective at rapidly coating magnetite (Fe₃O₄) nanoparticles, giving functionalized MNPs that target the surface receptors of 3T3 cells [3]. Similarly, condensing 3,4-dihydroxybenzhydrazide with a reducing sugar, a process often followed by cyclization, provides sugar-hydrazides with catechol functionality, a class of compound of particular interest. A high-throughput method has been developed which produces a range of saccharide-hydrazide adducts with good yield and anomeric purity upon condensation of a reducing sugar with 3,4-dihydroxybenzhydrazide.

The stability of the resulting catechol-nanoparticle coating has been analyzed and shows a significant improvement upon resorcinol analogues. The ability of sugar-coated nanoparticles to interact with a specific cell line was investigated by incubating the coated MNPs with either 3T3 fibroblasts or HepG2 carcinoma cells. A significant increase in specific interactions was observed for one sugar coating versus other types [4].

Recent work has looked at the synthesis of saccharide-terminated lipids using the same chemistry. Functionalization of the end of a commercially available lipid-polyethylene glycols (lipid-PEGs) gives lipid-PEG-hydrazides in good yield. A subsequent condensation reaction then leads to lipid-PEG-saccharides. It is hoped that these lipids can be inserted into phospholipid vesicles to form saccharide-functionalized vesicles for encapsulation and targeted drug delivery.

References:
(1) S. Laurent, D. Forge, M. Port, A. Roch, C. Robic, L. V. Elst and R. N. Muller, Chem. Rev., 2008, 108, 2064-2110.
(2) D. N. Ho, N. Kohler, A. Sigdel, R. Kalluri, J. R. Morgan, C. Xu and S. Sun, Theranostics, 2012, 2, 66-75.
(3) T. Coxon, A. Almond and S. J. Webb, MRS Proceedings, 2014, 1688.
(4) T. P. Coxon, T. W. Fallows, J. E. Gough and S. J. Webb, Org. Biomol. Chem., 2015, 13, 10751-10761.

Identifying novel cancer biomarkers is important for early cancer detection as it can reduce mortality rates. The cancer sectretome, the collection of all macromolecules secreted by a tumor cell, alters its composition compared to normal tissue, and this change plays an important role in the observation of cancer progression. The collection and accurate analysis of cancer secretomes could lead to the discovery of novel biomarkers, thus improving outcomes of cancer treatment. We unexpectedly discovered that enzyme-instructed self-assembly (EISA) of a D-peptide hydrogelator results in nanonets/hydrogel around cancer cells that overexpress ectophosphatases. Here we show that these nanonets are able to rapidly collect proteins in the pericellular space (i.e., near the surface) of cancer cells. Because the secretory substances are at their highest concentration near the cell surface, the use of pericellular nanonets to collect the cancer secretome maximizes the yield and quality of samples, reduces pre-analytical variations, and allows the dynamic profiling of secretome samples. This new approach has great potential in identifying the heterotypic signaling in tumor microenvironments thereby improving the understanding of tumor microenvironments and accelerating the discovery of potential biomarkers in cancer biology.

Open surgeries for implantation of artificial supporters have faced the problems such as increasing infection rates, delaying recovery time, and adapting irrelevantly on the defect site. Thus, minimal invasive surgeries have been developed in the last few decades to minimize weakness of open surgeries. As a material for artificial supports, injectable hydrogel microfibers have gained attention due to their biocompatibility, reachability at the deep site, and high filling ratio for the defect site. Among the methods of fabricating injectable hydrogel microfibers, photopolymerization based on microfluidic device has shown potential. Compared to other polymerization methods, photopolymerization has advantages of spatiotemporal control, rapid reaction, and good feasibility at room temperature.
This study introduces a synthesis method of injectable poly(ethylene glycol) diacrylate (PEGDA) microfibers. These are generated by catheter-based microfluidic device including optical fiber. This method has four advantages as follows: (1) employment of eosin Y as photoinitiator for a visible-light-curable material, which is biocompatible, rather than a UV-light-curable materials, (2) emission of visible light (532 nm wavelength) which is safer light source on a human body than UV light, (3) replacement of the external bulk laser with an optical-fiber-coupled laser that keeps the device small, and (4) integration within flexible catheter that enables to fabricate PEGDA microfibers in condition of inserting into the bending structure.
The device is assembled with a small catheter (1.0 mm diameter) and optical fiber (0.3 mm diameter) inserted into a large catheter (2.3 mm diameter) in parallel, where ends of the small catheter and optical fiber are placed 10 and 20 mm apart from the edge of large catheter respectively. PEGDA solution flows inside the small catheter and saline solution flows through the gap of the small and large catheter. The PEGDA solution flowing out the small catheter is covered by saline solution to be elongated and in situ polymerized by visible light emitted from optical fiber.
Proof of concept experiments are conducted with the device edge immersed in water. First, conditions of polymerization are investigated by controlling the flow rate of PEGDA and saline solution. When flow rates of PEGDA and saline solution are 6 and 280 mL/h respectively, PEGDA microfibers with mean diameter of 150 m are generated. Seconds, delivery of PEGDA microfibers into two test models with a saccular cavity (5 and 10 mm diameter) and arched passage is performed to assess delivery feasibility. From this delivery, we find that our system completely contain PEGDA microfibers within the test models with spatiotemporal control.
This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number : HI15C0001).

Gels have 3D polymer network structures that enable them to hold onto other molecules such as solvents, aroma chemicals, and drugs. By preparing gels using stimuli-sensitive polymers, we can provide desired functions to the gels. Poly(N-isopropylacrylamide) (PNIPA) is a functional polymer that alters its solubility in water as a function of temperature. PNIPA gels have been widely applied to thermo-sensitive advanced soft-materials for the purpose of cell culture substrata, and drug deliveries. Gels exist in our daily lives and industrial fields today because of their simple preparation as well as multiple functions. Free radical polymerization has been used as a conventional method for preparing gels due to its broad applicability for various monomers and its ease in handling. However, general polymer networks prepared by free radical polymerization have several inhomogeneities that cause a decline in the functions of gels. Development of facile methods for creating homogeneous polymer networks with identical average sub-chain length must facilitate the applications of gels to a wider range of fields.
This work proposes a new approach to prepare a PNIPA gel with a homogeneous polymer network in one-pot using fast controlled radical polymerization in combination with slow step-growth radical polymerization. M. Kamigaito has reported that CuCl-Me₆TREN catalytic system is available for both fast controlled radical polymerization and slow step-growth radical polymerization of NIPA. By combining these reactions, we prepared a PNIPA gel from NIPA, tetra-halogenoalkane as an initiator, and tetra-allylic compound as a cross-linker. Herein, we report the synthesis process and the physical properties of the resultant PNIPA gel.
First, we prepared a tetra-branched PNIPA using the fast controlled radical polymerization to check the reaction velocity and the polydispersity index (PDI) of the polymer obtained. NIPA was immediately consumed after the onset of the reaction: the total conversion was over 90% within one hour. The PDI of the resultant PNIPA was low (~ 1.2). Second, we prepared a PNIPA gel under a condition where the cross-linker was also added to the solution. The solution turned into a gel after several hours, indicating that the step-growth radical polymerization between the tetra-branched PNIPA and the cross-linker was achieved after completion of the controlled radical polymerization. The gel obtained had high transparency and elasticity.
In summary, a PNIPA gel was successfully prepared in one-pot using the combination of the fast controlled radical polymerization and the slow step-growth radical polymerization. In the presentation, we will discuss the homogeneity of the polymer network. This one-pot method allows for the synthesis of particular gels simply by just mixing the necessary ingredients, and will affect various scientific and industrial fields, thereby expanding ways in which gels can be applied.

Polymer gels consist of polymers chains cross-linked to create three-dimensional networks. Thanks to the variety of functions of polymer gels, they are widely used as soft contact lenses, and many toiletry products such as a diaper. As it is, practical applications of polymer gels can be restricted because of their low mechanical strength, which is ascribed to the inhomogeneity of the cross linking points. The formation of homogeneous network structures must lead to the improved mechanical strength of polymer gels. The aim of this research is synthesis of poly(N-isopropylacrylamide) (PNIPAM) gels composed of a homogeneous network. PNIPAM is a thermo-responsive polymer and exhibits a lower critical solution temperature (LCST) of 32°C in water. Its thermo-responsive property is potentially useful for many biomedical applications such as drug deliveries and actuators.
To precisely prepare the homogenous network composed of PNIPAM, we used step-by-step procedure employing a living radical polymerization, and click chemistry as follows. First, a tetra-branched PNIPAM with the same molecular weight was synthesized by living radical polymerization using N,N ’-ethylenebis(2,2-dichloroacetamide) as an initiator. The consumption of NIPAM was determined by ¹H NMR. NIPAM was immediately consumed after the onset of the reaction: the total conversion was over 99% within 120 minutes. According to the result of size exclusion chromatography (SEC), the tetra-branched PNIPAM had narrow molecular weight distributions (Mw/Mn~1.08). Second, the four chloro-terminations of the tetra-branched PNIPAM were substituted with azide by using sodium azide. Judging by the FT-IR spectrum of the product obtained, we could prepare an azide-terminated tetra-branched PNIPAM because a new absorbance peak, which is attributable to the azide group, was observed at 2036 cm^-1. Third, the amine- or carboxyl- terminated tetra-branched PNIPAM was prepared by the reactions between the azide-terminated tetra-branched PNIPAM and dibenzocyclooctyl derivative with amino group or carboxylic acid group. This click is relatively fast, and specific without any catalyst. The peak at 2036 cm^-1 in the FT-IR spectrum, which is derived from azide group, was disappeared for the products. We confirmed that amine- and carboxylic acid- groups were successfully introduced to the terminations of tetra-branched PNIPAM. As mentioned above, we respectively synthesized amine- and carboxylic acid- terminated tetra-branched PNIPAM with narrow molecular weight distributions.
We will report the preparation of homogeneous networks polymer gels by the condensation reaction between the amine and the carboxylic acid terminations of these tetra-branched PNIPAM.

We report the facile synthesis of a new multifunctional colloidal hybrid system (MG@FePt) by loading a thermoresponsive swellable amphiphilic poly(N-vinylcaprolactam) microgel (MG) with superparamagnetic sub-10 nm FePt nanoparticles (NPs) by using a solvent exchange method. The efficient loading of the microgels with FePt NPs is evidenced, on the one hand, via TEM measurements in the dried state of the MG@FePt, and on the other hand, via cryo-TEM and in situ STEM measurements in the swollen state of the MG@FePt. We determined the maximum amount of FePt NPs, which can be loaded into the microgels. Furthermore, we analyzed whether the embedded FePt NPs influence the microgels properties, in particular swelling and temperature-triggered volume phase transition (VPT), or the microgel’s influences the magnetic properties of the FePt NPs. MG@FePt are colloidally stable in water and exhibit similar thermal responsiveness as the unloaded microgel, evidenced by temperature dependent DLS measurements. Both FePt NPs and MG@FePt show superparamagnetic properties with significantly enhanced saturation magnetizations for the highly loaded microgels. Cell tests with HeLa cells show no cytotoxic effect for the microgels with the highest loading of FePt NP.

Hence, the new hybrid material introduced here (i) is colloidally stable in water and the thermo-responsive properties in terms of a VPT is retained, (ii) exhibits superparamagnetic characteristics introduced by FePt NPs, (iii) shows a drastically reduced cytotoxicity compared to other water soluble FePt NP of similar size, as known from literature. This makes them particularly interesting for applications in biological environments, e.g. as biocompatible stimuli responsive containers for drug delivery or for imaging.

The macroscopic healing rate and efficiency in self-repairing hydrogel materials are largely determined by the dissociation dynamics of their polymer network, which is hardly achieved in a controllable manner. Inspired by mussel’s adhesion chemistry, we developed a novel approach to assemble inorganic nanoparticles and catechol-decorated PEG polymer into a hydrogel network. When utilized as reversible polymer-particle crosslinks, catechol-metal coordination bonds yield a unique gel network with dynamic mechanics controlled directly by interfacial crosslink structure. Taking advantage of this structure-property relationship at polymer-particle interfaces, we designed a hierarchically structured hybrid gel with two distinct relaxation timescales. By tuning the relative contribution of the two relaxation modes, we are able to finely control the gel’s dynamic mechanical behavior from a viscoelastic fluid to a stiff solid, yet preserving its rapid self-healing property without the need for external stimuli.

In the current shift away from physiologically irrelevant 2D tissue culture polystyrene and towards 3D cell culture substrates, several important design criteria have yet to be considered: (1) provision of large open areas where cells can form their own niche (2) fabrication of a scaffold with spatially controlled chemical and mechanical properties and (3) presentation of proteins that mimic native extracellular matrix (ECM). 3D jet writing scaffolds, innovated in the Lahann Lab, have achieved cell to polymer ratios upwards of 2,000 cells per microgram. At only about four percent material, and 96% open area, these microfiber scaffolds minimize contact between synthetic and biological moieties, and allow cells extensive void space for maximized cell-cell and cell-ECM interactions. By implementing a micro-manifold into the 3D jet writing process, material deposition throughout the scaffold is now controlled in three dimensional space. This allows for fabrication of customized microfiber scaffolds that include domains of distinct mechanical, chemical, or surface functionalities. Such tunability is not only limited to the synthetic design space; fibronectin, collagen, and other ECM proteins can be suspended within the open areas of the scaffold either independently or in combinations. The resulting fibronectin conformation mimics that of cellularly-deposited ECM, providing the capability to explore how the protein composition of the microenvironment impacts cell behavior. Fibronectin scaffolds recapitulate the breast cancer cell niche and serve as a model of metastasis. Additionally, these scaffolds have improved the efficiency of mouse breast tumor graft formation, allowed expansion of patient derived breast cancer cells, and enhanced cancer stem cell populations. Ewing sarcoma cells have also been cultured on fibronectin scaffolds to observe matrix remodeling. Other studies in the Lahann Lab have demonstrated successful culture of a variety of cell types on fibronectin scaffolds including embryonic and adult stem cells, pancreatic and prostate cancer cells, and endothelial cells. This versatile, user-defined 3D cell culture system is amenable to standard characterization techniques; it provides a means to independently probe the effects of environmental parameters on cell behavior, and overall serves as a promising future alternative to the ubiquitous petri dish.

Stimuli-responsive hydrogels are currently an active subject of research for biological applications including drug delivery, synthetic tissues, and studying cell interactions with their surroundings. Conventional, covalently crosslinked hydrogels are typically too weak to function mechanically, so researchers have turned to creating hydrogels with more diverse architectures, including hydrogels where the interactions between polymer chains are dynamic and reversible. This leads to hydrogels with vastly improved mechanical strength and toughness over conventional hydrogels. However, there exist a vast array of supramolecular chemistries to choose from, including ionic interactions, hydrophobic associations, adaptable covalent bonds, hydrogen bonds, protein-inspired associating domains, host-guest complexes, or metal-ligand coordination. Each of these strategies to design supramolecular networks have varying advantages and disadvantages, from ease/efficiency of synthesis to range of mechanical properties to stimuli-responsiveness.

In order to design hydrogels with optimized mechanical properties, we must consider viscoelastic properties, as supramolecular soft materials exhibit characteristic timescales across orders of magnitude in time. Recently, we showed that, in a polyethylene glycol (PEG)-based hydrogel crosslinked by bio-inspired Histidine:M²⁺ coordinate bonds, the characteristic mechanical relaxation timescale can be controlled by selecting the transition metal ion acting as the crosslink center. Further, we showed that by using mixed transition metals, we are able to design hydrogels with multiple hierarchical relaxation timescales while controlling the magnitude of the timescales by varying the relative metal concentrations. This platform of PEG-His:M²⁺ hydrogels represents a straightforward method for creating hydrogel materials with precisely-engineered viscoelastic energy dissipation properties.

Here, we expand on this platform by exploiting the chemistry of metal-coordinate complexes to create hydrogels with UV-responsive viscoelastic properties, where the oxidation state of the transition metal can be altered using a UV-generated radical. Since some transition metals are more susceptible than others to reduction or oxidation, careful selection of the metal ion crosslink mixture and UV exposure allows a diverse set of (neat viscoelastic timescales) - (UV-triggered viscoelastic timescales) pairs. Such a precise level of control over hierarchal energy dissipation modes enables optimization of hydrogel mechanics for a wide array of loading contexts.

Ectoenzymes, which have the catalytic domains outside the plasma membrane of cells, usually carry out dual or multiple functions in many types of cells. Despite overexpression of ectophosphatases represents a generic difference between certain cancer and normal cells, the evaluation of their activities is rather difficult and receives little attention. Here we report the profiling of the activities of ectophosphatases on cancer cells by enzyme-catalyzed self-assembly of a D-peptidic hydrogelators that form fluorescent molecular nanofibrils. Possessing an environment-sensitive fluorophore and an enzyme substrate (i.e., phosphorylated tyrosine), the designed precursor can turn into the corresponding hydrogelator via enzyme-instructed dephosphorylation, which results in the self-assembly of the hydrogelator and gives enhanced fluorescence. Our study reveals the significantly higher activities of ectophosphatases on cancer cells than on stromal cells in co-culture and shows an inherent and dynamic difference in phosphatase activities between drug sensitive and resistant cancer cells or between cancer cells with and without hormonal stimulation. Besides providing an approach to achieve high spatiotemporal resolution for profiling the activities of phosphatases, a ubiquitous class of enzymes, in mixed population of live cells, the integration of enzyme catalysis with self-assembly serves as a novel approach to profile the activities of enzymes and to control the fate of cells.

Injecting vaccines via hypodermic needles results in hazardous sharps waste and patient discomfort. Microneedle arrays, which have been previously shown to deliver subunit and attenuated viral vaccines to the immune cells in the dermis, are currently being studied as a means to circumvent these issues. An additional advantage of using implantable, polymeric microneedles is that they can be designed to achieve tunable sustained release kinetics. Previously published work includes silk, polysaccharide, polymer blend, and particle-based microneedles, and extended release has been shown to elicit strong immune responses. Here, a new type of microneedle was constructed from a maleimide grafted poly(propargyl l-glutamate) (PPLG) polymer and contained a model vaccine of ovalbumin and a TLR3 agonist, poly(I:C). A heterogeneous reaction between a thiol containing poly(ethylene glycol) dithiol in methanol and the solid microneedle tips was shown to crosslink the surface of the microneedle array tips. These implantable, crosslinkable microneedles were also used to immunize mice. Further, controlled release of ovalbumin was observed from surface crosslinked PPLG tips. These results could provide a way to generate complex temporally controlled release profiles that would depend on the extent of maleimide functionalization, crosslinking agent, and crosslinking conditions. Continued studies are exploring incorporating HIV antigen into PPLG microneedles for in vivo immunizations.

Breast cancer preferentially metastasizes to bone and induces pathological tissue remodeling. The nanoscale materials properties of bone apatite crystals have been implicated in breast cancer metastasis. However, it remains a challenge to deconvolute the roles of surface chemistry and surface topography in this process. To solve this problem, we used geologic hydroxyapatite (HAP, Ca₁₀(PO₄)₆(OH)₂), a calcium phosphate mineral with structural and mechanical properties similar to bone apatite, to investigate whether HAP surface chemistry and nanoscale topography alter the crystal/protein interface in the bone extracellular matrix (ECM), and how the altered ECM impacts breast cancer cell activities. We first utilized Förster resonance energy transfer (FRET) to assess the molecular conformation of fibronectin (Fn), a major ECM protein upregulated in cancer, when it adsorbs onto HAP facets. Our analysis reveals that Fn adopted more compact conformations (i) when interacting with HAP surfaces with denser surface charge, regardless of surface roughness, and (ii) when HAP surfaces were rougher, regardless of surface chemistry. We next seeded MDA-MB-231 breast cancer cells onto those Fn-coated HAP facets. Our data show elevated cell secretions of proangiogenic and proinflammatory factors associated with more unfolded Fn adsorbed onto nano-rough HAP facet with low surface charge density. These findings not only deconvolute the roles of crystal surface chemistry and nanoscale topography in interfacial ECM deposition but also enhance our knowledge of protein-mediated breast cancer cell-apatite interactions that may be implicated in bone metastasis.

An effective and personalized pain treatment without major side effects would greatly benefit patients. Current treatments of pain are mainly based on opioids, with substantial side effects, can be addictive, and be diverted to illicit ends. Conventional local anesthetics may be effective, but do not last for a long time (typically 6-12 hours). Even though controlled release formulations for prolonged local anesthesia have been reported ¹ and researchers have shown prolonged local anesthesia for up to 1 week, these formulations have the major limitation that once administered, the drug release profile could not be changed according to the patient’s changing conditions. An on-demand local anesthesia system with which the patient could effectively, non-invasively and repeatedly control the timing and dosage of anesthetics according to their changing conditions for the duration of treatment, would enhance the patient’s quality of life.
To realize these goals, here we report a local anesthetic formulation whose drug release could be triggered with a non-invasive energy source. The formulation was based on a liposomal drug delivery system with energy-absorbing sensitizers encapsulated in the liposome bilayer, and the liposome was made labile to reactive oxygen species. Upon triggering, reactive oxygen species would be released via the sensitizers and induce lipid peroxidation, enhancing the permeability of the liposomes, resulting in drug release. In vitro experiments showed successful drug release upon triggering. In vivo experiments demonstrated triggerable nerve blocks that were repeatable and adjustable by controlling the triggering parameters, such as intensity and duration. Such on-demand, externally triggerable and adjustable local anesthesia system would benefit pain management and enhance the applicability of personalized pain treatment.
1. Epstein-Barash, H.; Shichor, I.; Kwon, A. H.; Hall, S.; Lawlor, M. W.; Langer, R.; Kohane, D. S., Prolonged duration local anesthesia with minimal toxicity. Proc Natl Acad Sci USA 2009, 106, 7125-7130.

The synergistic combination of nanotechnology and biology has resulted in numerous innovative approaches for sensors, new therapies for diseases, and biomolecular machines. One of the most exciting prospects of nanotechnology is that nanoparticles can act as a “handle” by which one can control nanoscale processes, in particular biological function. Unfortunately, one of the biggest challenges for effectively using nanoparticles in biology is non-specific adsorption, where proteins and DNA non-covalently stick to nanoparticles. This often results in formation of a protein corona, a cloud of weakly bound proteins surrounding the nanoparticle. However, non-specific adsorption can actually be exploited for biological applications. We demonstrate a means to reversibly control blood clotting with laser excitation by using the unique size and shape dependent properties of gold nanorods as well as exploiting their tendency to adsorb to proteins. In addition, we will discuss the use of gold nanoparticles in rapid diagnostics for different infectious diseases in rugged environments. We exploit the size-dependent optical properties of Ag and Au NPs to construct a multiplexed paperfluidic lateral flow POC sensors for dengue, ebola, yellow fever, zika, and chikungunya viruses. NPs of different sizes were conjugated to antibodies that bind to specific biomarkers, resulting in different colors for a multiplexed sandwich immunoassay.

Superparamagnetic iron oxide nanoparticles (SPIOs) have been used as MRI contrast agents in clinical diagnosis because of their superior detection limit in T₂-weighted MRI. They can also be incorporated into sensors for imaging biological calcium ions (Ca²⁺), which are essential to cellular signal transduction and to synaptic transmission in the brain. Although several SPIO-based Ca²⁺ sensors have been developed, none has been shown to detect calcium fluctuations in brain. Here we present a novel Ca²⁺ sensor formed from a hybrid system of interacting magnetic nanoparticles and proteins, and we demonstrate its validation in live animals. To target calcium fluctuations in the brain’s extracellular space, we utilized a low-affinity calcium sensing protein that is capable of inducing calcium-dependent clustering of appropriately functionalized SPIOs. Ca²⁺ concentration changes could be detected as signal changes in T₂-weighted MRI because SPIO clustering causes substantial changes in T₂ relaxation rate (R₂). Atomic force microscopy and dynamic light scattering directly revealed calcium-dependent changes in the clustering state of the sensor. A titration curve of R₂ vs. [Ca²⁺] shows responses in the concentration range relevant to extracellular Ca²⁺ fluctuations during neural activity. Responses are reversible and relatively fast, taking place with a time constant of about 5 s. Intracranial injections were performed in conjunction with manipulations designed to test calcium sensitivity in the living rat brain. Chemically-induced brain stimulation in the presence of the sensor produces transient increases in MRI intensity. Signal changes were not observed under control stimulation conditions or in the presence of an inactive SPIO-based sensor analog. These results constitute the first demonstration of calcium-dependent molecular MRI in living brain, and offer a precedent for application of SPIO-based MRI sensors to functional bioimaging more generally.

We develop a novel strategy for intracellular self-assembly by targeting mitochondrial organelles that control the fate of cancer cell. Utilizing the unique property of tumor microenvironment, such as overexpression of enzymes (Alkali phosphatase), we design peptide molecule which can enter into the cancer cells, forming nanostructures by overexpressed enzymes, resulted in cancer cell death but not normal cell. What’s more, due to the greater viscosity in the mitochondrial matrix of tumor cells, the critical micelle concentration could descend, which can enhance the cytotoxicity of molecular nanostructure. Detail experiments indicate that the precursor itself can form nanoparticles, once added to the cell surface, ectoenzyme convert this nanoparticles to nanoribbon, which can enter the cell via endocytosis pathway and escape from endosome. The fluorescent imaging, western blot and cell fractionation experiments indicate that the molecule self-assemble and localize to the mitochondria, which dysfunction and release cytochrome c, resulted the necrosis of cancer cell. This work demonstrates the construction of nanostructures via enzyme-triggered supramolecular self-assembly target mitochondria without forming the covalent bond. This approach could be applied to self-assembly triggered by other enzymes or target other organelles.

References:
1.Gao, Y.; Shi, J. F.; Yuan, D.; Xu, B*.“Imaging enzyme-triggered self-assembly of small molecules inside live cells” Nat. Commun. 2012, 3, 1033.
2.Kuang, Y.; Shi, J. F.; Li, J.; Yuan, D.; Alberti, K. A.; Xu, Q. B.; Xu, B.* “Pericellular Hydrogel/Nanonets Inhibit Cancer Cells” Angew. Chem. Intl. Ed., 2014,53, 8104-8107.
3.Zhou, J.; Du, X. W.; Li, J.; Yamagata, N.; Xu, B.* “Taurine Boosts Cellular Uptake of Small D-peptides for Enzyme-Instructed Intracellular Molecular Self-assembly”, J. Am. Chem. Soc. 2015, 137, 10040-10043.