Benedetto Marelli, Massachusetts Institute of Technology
Fiorenzo Omenetto, Tufts University
Jelena Rnjak-Kovacina, University of New South Wales
Hu Tao, The University of Texas at Austin
Shanghai Runshuo Medical Instrument Co., Ltd.
BM11.01: Protein-Based Biopolymers I—Form and Function
Monday AM, November 27, 2017
Sheraton, 2nd Floor, Liberty BC
8:30 AM - *BM11.01.01
Silk Protein Polymer Composites—New Structures and Functions
David Kaplan 1 Show Abstract
1 , Tufts University, Medford, Massachusetts, United States
Silk is one of the oldest biomaterials, utilized in textiles and as sutures for centuries, and now undergoing a rebirth into new biomaterial formats and applications over the recent decade. One key to this emergence has been the exploitation of the novel features of silk but with new modifications of the native protein using processing methods and chemistries. These changes have led to the engineering of new material features and functions. Some of the recent strategies developed to morph silk into new materials with new properties will be discussed, including new processing modes, new silk-polymer composite systems, and new modes to bioengineer silk protein polymers to add new chemistry. In all cases, the goal is to exploit the inherent features of silks while adding new functional features. The maintenance of themes of green processes, biocompatibility, full degradation, and self-assembly, without the need for chemical or photochemical crosslinking, remain at the heart of these studies. The results should foster broader uses of silk in many areas of technology, from medicine to environmental applications.
9:00 AM - BM11.01.02
Hydrodynamically Assembled Nanostructured Bio-Based Materials
Nitesh Mittal 1 , Fredrik Lundell 1 , Daniel Soderberg 1 Show Abstract
1 , KTH Royal Inst of Technology, Stockholm Sweden
The need for high-end multifunctional materials from bio-based resources has been evolved by a rapidly increasing population and accompanying environmental concerns. However, lack of scalable assembly methods has been a key block in manufacture of high-performance nanostructured materials. I would like to present material concepts using components from bio-based resources, to achieve extraordinary performance of the macroscopic materials. We utilized fluid-phase assembly process as it is the most promising method for producing large, ordered structures for nanoscale objects.
I would like to brief our approach in context to different nanoscale building blocks from the bio-based resources.
Amyloids. Controlling the aggregation process of protein-based macromolecular structures in a confined environment is essential to develop bio-based materials. Whey protein, a protein mixture protein with β-lactoglobulin as main component, can self-assemble into amyloid-like protein nanofibers which are stabilized by hydrogen bonds. The conditions at which the fibrillation process occurs can affect the properties and morphology of the fibrils. We show that the morphology of protein nanofibers greatly affects their assembly. We used elongational flow based double flow-focusing device for this study. In-situ behavior of the straight and curvy fibrils in the flow channel is determined using small-angle X-ray scattering (SAXS) technique. Our process combines hydrodynamic alignment with dispersion to gel-transition that produce homogeneous and smooth 100% protein fibers.
Nanocellulose/Recombinant Spider Silk Proteins. Wood-based cellulose nanofibrils are strong and stiff, but non-bioactive. Smart combinations with bioactive proteins opens opportunities to use them for advanced biomedical applications. Additionally, the high elasticity of spider silk, together with exceptional stiffness of cellulose nanofibrils, can expedite tough and lightweight nature-friendly materials. We combined hard and soft matrix of cellulose nanofibrils and recombinant spider silk proteins, respectively, to fabricate hierarchical structures that achieves extraordinary mechanical properties and bio-functionalities.
1. Ayaka Kamada*, Nitesh Mittal*, L. Daniel Soderberg, Tobias Ingverud, Wiebke Ohm, Stephan Roth, Fredrik Lundell, Christofer Lendel, “Flow-assisted assembly of nanostructured protein microfibers”, Proceedings of the National Academy of Sciences of the United States of America, 2017, 114 (6), 1232-1237. (*equal contribution)
2. Nitesh Mittal, Ronnie Jansson, Mona Widhe, Tobias Benselfelt, Karl Hakansson, Fredrik Lundell, My Hedhammar, L. Daniel Soderberg, “Ultrastrong and bioactive nanostructured bio-based composites”, ACS Nano, 2017, 11 (5), 5148-5159.
9:15 AM - BM11.01.03
A 3D Hierarchical Silk Fibroin Nanoparticle-Based Electrode as Immunoelectrochemical Interface for Early Detection of Amyloid-Beta
Ta-Chung Liu 1 , San-Yuan Chen 1 , You-Yin Chen 2 , Chao-Yi Chu 1 Show Abstract
1 , National Chiao-Tung University, Hsin Chu Taiwan, 2 , National Yang Ming University, Taipei Taiwan
In point-of-care (POC) tests, a nano-enable interface with low limit of detection and an easy strategy to integration into automated Micro-electromechanical Systems (MEMS) device are urged to be developed. In this work, a strategy to prepare a newly-designed 3D hierarchical immune-electrochemical interface with conductive silk fibroin-based nanoparticles (CSPs) is presented. With this aid of electropolymerized PEDOT bridging silk-based spheroids, the 3D hierarchical nanostructured bulk interface formed with high porosity and surface areas, which allowed analytic biomolecules penetrate into the bulk matrix to exhibit higher sensitivity than planar sensing interface. Compared with conventional electrophoresis, the one-step electrophoresis accompanied with electropolymerization using CSPs gives the nanostructured interface much more strong adhesion to electrode/interface for achieving stable signals. For proof-of-concept validation, the optimal sensitivity (LOD=6.6 pg/ml) of this immnoelectrochemical interface integrated with microelectrode array (MEA) is capable of applying in 3×Tg-AD mice serum detection. This study greatly expands the applications of silk-based materials and would also be valuable in the design of new types of electrochemical biosensors for the detection of other diseases.
9:30 AM - BM11.01.04
20-nm Thin Fibrils Confirmed as the Sole Structural Component in a Spider Silk
Qijue Wang 1 , Hannes Schniepp 1 Show Abstract
1 , College of William & Mary, Williamsburg, Virginia, United States
The silk of the brown recluse spider features the mechanical characteristics typical of a spider silk, with strength and toughness values rivaling the highest-performing silks in the literature. Despite great interest in these materials, many details of their hierarchical structure, from the molecular scale up, remain unclear. Using atomic force microscopy, electron microscopy, and focused ion beams, we have been able to prove for the first time that these spider silk fibers are completely composed of relatively weakly bound nanofibrils featuring diameters around 20 nm, oriented parallel to the fiber axis. While such nanofibrils have been observed on the surface of many silk fibers, and occasionally on the inside, our observation that the nanofibrils are the sole structural element of silk fibers represents a significant advancement of the understanding of silk.
9:45 AM - BM11.01.05
Silk Fibroin and 2D Titanate Nanocomposites for Biopolymer-Based Optical and Environmental Devices
Giovanni Perotto 1 , Elena Colusso 3 , Davide Magrì 1 , Fiorenzo Omenetto 2 , Despina Fragouli 1 , Alessandro Martucci 3 , Athanassia Athanassiou 1 Show Abstract
1 Smart Materials, Italian Institute of Technology, Genova Italy, 3 , Università degli Studi di Padova, Padova Italy, 2 , Tufts University, Medford, Massachusetts, United States
The development of nanocomposite materials able to combine characteristics inherent to the biopolymers, such as biocompatibility and biodegradability with functional properties of inorganic nanoparticles attracted a great interest in the last decades .
Here we report the synthesis of easy-tailored high refractive index nanocomposite made of silk fibroin and titanate nanosheets (TNSs).
Silk fibroin, derived from Bombyx mori cocoons, is a widely used and studied protein due to the combination of mechanical properties, biocompatibility, tunable biodegradability and ease of fabrication. Recently, it has been proposed as a platform for biocompatible optics, high tech application like resorbable electronics, and implantable and biofunctional optical devices .
From an optical standpoint, to enhance the performances of silk as a material for optics while preserving all its specific properties, silk fibroin was combined with titanate nanosheets (TNSs). TNSs are layered 2D crystals of sub-stechiometric TiO2, synthetized by sol-gel chemistry, that were chosen because of their small size, high and tunable refractive index and their water dispersability, which makes the integration with silk processing very easy to implement.
The structural and functional characterizations of the new composite were performed to correlate functionality and structure. The different fabrication techniques already developed for pure silk were applied on the high refractive index nanocomposite demonstrating the possibility to fabricate optical devices with increased performances due to the increased refractive index .
In particular, a bioinspired multilayer optical structured was fabricated with the new material, showing a stimuli-responsive behavior which results in a reversible change of structural coloration in response to the surrounding environment. As the beetle Hoplia coerulea is able to modify its color in the presence of moisture, thanks to the variation of the thin films stack responsible for the interference color, in the same way our structure can sense the environmental humidity with a reversible mechanism and transduces the change in a colorimetric scale. 
The silk and TNSs composite showed also a great potential for efficient removal of metal pollutants from water thanks to its specificity towards heavy metals like Pb and the high absorption capacity. The biomaterial’s matrix can provide forms able to facilitate the use of these adsorbents and at the same time reduce the risk of release of nanostructures in the aqueous medium.
 M. Darder, P. Aranda, E. Ruiz-Hitzky, Adv. Mater. 2007, 19, 1309.
 F.G. Omenetto and D.L. Kaplan, Nature Photonics 2008, 2, 641.
 G. Perotto, M. Cittadini, H. Tao, S. Kim, M. Yang, D. L. Kaplan, A. Martucci, F. G. Omenetto, Adv. Mater. 2015, 27, 6728.
 E Colusso, G Perotto, Y Wang, M Sturaro, F Omenetto, A Martucci, Journal of Materials Chemistry C, 2017, 5, 3924
BM11.02: Protein-Based Biopolymers II—Assembly and Processing
Monday AM, November 27, 2017
Sheraton, 2nd Floor, Liberty BC
10:30 AM - BM11.02.01
Concentration Dependent Thermal Response of Silk-Elastin-Like Protein Hydrogels—Integrating Multiscale Computational Modeling with Experiments
Jingjie Yeo 1 2 , Wenwen Huang 3 , Anna Tarakanova 1 , David Kaplan 3 , Markus Buehler 1 Show Abstract
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 , Institute of High Performance Computing, Singapore Singapore, 3 , Tufts University, Medford, Massachusetts, United States
Protein polymers are vital for developing dynamically adaptable hydrogels as opposed to static designs that are predominant in current biomedical usage. An example is silk-elastin-like protein (SELP) hydrogels which are reversibly responsive to multiple stimuli. In particular, the thermal response of SELPs constructed from SE8Y and S4E8Y repeat are investigated. For SE8Y, experimental results showed a reversible size transition as temperature increased beyond 294K with corresponding decreases in optical absorbance and pore sizes, while the mechanical stiffness increased. Such a transition was significantly suppressed in S4E8Y repeats. Fully atomistic molecular dynamics (MD) modeling showed that the molecular origin of the SE8Y SELP thermal response is due to a decrease in the end-to-end length and the solvent-accessible surface area (SASA) of a single SELP molecule. As conformational sampling of proteins in conventional MD modeling is limited by rough potential energy landscapes, the experimental inverse temperature transition of SELPs is effectively captured by sampling smoother energy landscapes through coarse-grained (CG) MD simulations at a range of temperatures from 277K to 330K. Both the SASA and the radius of gyration of a single SE8Y SELP molecule showed a steep decrease above a temperature of 297K, in good agreement with the experimental transition temperature of 294K. This CG model also accurately captured the suppressed temperature transition in S4E8Y molecules. By extending the model with dityrosine crosslinking capabilities, experimental observations that increasing SELP concentration diminishes the thermal response is determined to be a result of molecules being trapped in a state of higher potential energy. This reduced their ability to adopt a more closely packed conformation beyond the transition temperature.
10:45 AM - BM11.02.02
Characterization and Selective Modifications of Enzyme-Crosslinked Silk Hydrogels for Rational Biomaterial Design
Meghan McGill 1 , David Kaplan 1 Show Abstract
1 , Tufts University, Medford, Massachusetts, United States
Hydrogels from naturally-derived silk polymers offer versitile opportunities in the biomedical field, however, their design has largely been an empirical process.The present study describes a molecular and macro-scale investigation of enzymatically-crosslinked silk fibroin hydrogels, and demonstrates that these systems have tunable crosslink density and diffusivity. We developed a liquid chromatography tandem mass spectroscopy (LC-MS/MS) method to quantify the covalent tyrosine crosslinks present in silk hydrogels, and employed rheological analysis and fluorescent recovery after photobleaching (FRAP) analysis to study their modulus and diffusive properties. This work revealed a non-linear relationship between the silk concentration and the modulus and diffusivity of silk hydrogels. By changing the radical initiator concentration and silk concentration, conversion of tyrosine to dityrosine in silk hydrogels could be varied between 28 and 56%, and the diffusion behavior could be modulated. Modifications were made to select amino acid residues in the silk backbone to add functional peptides or cleavable spacers, further increasing our ability to engineer silk hydrogels for a variety of biomedical applications.
11:00 AM - *BM11.02.03
Silk-Based Self-Assembly and Lithography
Sedat Nizamoglu 1 Show Abstract
1 , Koc University, Istanbul Turkey
Patterning of materials from molecular- to macro-scale have facilitated significant advancement to the modern technology through the fabrication of integrated circuits, microelectromechanical systems (MEMS) [i], implantable devices [ii] and bio-patterning [iii],[iv]. However, in general these techniques require complex methods and the use of toxic materials. Therefore, simple lithographic techniques combined with environmentally friendly materials are desirable. In this talk I will discuss new methods to build functional devices via silk-based self-assembly and lithography. These techniques enable 2D and 3D fabrication of optical, electromagnetic and biological functional interfaces and devices.
[i] J. W. Judy, Smart Mater. Struct., 2001, 10, 1115
[ii] K. Scholtena, E. Meng, Lab Chip, 2015,15, 4256-4272
[iii] R. S. Kane, S. Takayama, E. Ostuni, D. E. Ingber , G. M. Whitesides, Biomaterials, 1999, 20, 2363.
[iv] D. B. Weibel, W. R. DiLuzio, G. M. Whitesides, Nature Rev. Microbiol., 2007, 5, 209.
11:30 AM - BM11.02.04
Fabrication of Elastomeric Silk Fibers
Sarah Bradner 1 , Benjamin Partlow 1 , Peggy Cebe 2 , Fiorenzo Omenetto 1 , David Kaplan 1 Show Abstract
1 Biomedical Engineering, Tufts University, Medford, Massachusetts, United States, 2 Physics and Astronomy, Tufts University, Medford , Massachusetts, United States
Advances in tissue engineering have taken up bottom-up designs by adapting biomaterials with fiber morphology as fundamental building blocks. Most recently, hydrogel microfiber fabrication has been explored for these needs due to the ability to recapitulate native-like microenvironments for cell encapsulation. Common hydrogel microfibers utilized for such purposes are in need of robust or tunable mechanical properties as well as more uniform fabrication processes. The objective of this work was to exploit features of silk fibroin protein for the formation of tunable and controllable silk hydrogel microfibers. The goal was to combine the advantages of the favorable biological, chemical, morphological, and mechanical design features inherent to silk fibroin with elastomeric properties gained through enzymatic-mediated oxidative cross-linking. Variable post-processing techniques coupled with the polymer swelling state can be exploited to induce a range of physical and chemical cross-links in the microfibers fabricated; further modulating properties. Post-processing via methanol and autoclaving provided tunable control of fiber features. Mechanical, optical, and chemical analyses demonstrated control of fiber properties by exploiting the physical cross-links, and generating double network hydrogels consisting of chemical and physical cross-links. Structure and chemical analyses revealed crystallinity from 30-50%, modulus from 0.5 MPa to 4 MPa, and ultimate strength 1 to 5 MPa, depending on the processing method. Fabrication and post-processing provided fibers with extensibility from 100 to 400% ultimate strain. Fibers strained to 100% exhibited 4th order birefringence, revealing macroscopic orientation driven by chain mobility. The physical cross-links were influenced in part by the drying rate of fabricated materials, where bound water, packing density, and micro-structural homogeneity influenced cross-linking efficiency. The ability to generate robust and versatile hydrogel microfibers is desirable for bottom-up biological tissues and for broader biomaterial applications.
11:45 AM - BM11.02.05
Preparation of Mechanically Stable κ-Casein Fibrils and Microcapsules via the Layer-by-Layer Deposition
Jubong Lee 1 , Ji-Hye Lee 1 , Bongjun Yeom 2 , Kookheon Char 1 Show Abstract
1 , Seoul National University, Seoul Korea (the Republic of), 2 , Myongji University, Seoul Korea (the Republic of)
Amyloid fibrils are naturally occurring insoluble protein aggregates induced by the cross b-sheet stacking. k-Casein, one of the amyloid precursors extracted from bovine milk, is a promising candidate as a reinforcing nanomaterial in the preparation of nanocomposites taking advantages of mechanical robustness and bio-degradability. In physiological condition, k-caseins, classified as intrinsically disordered proteins, have relatively little secondary or tertiary structures and extremely flexible. We induced k-casein fibrils under thermal incubation in reducing condition, and traced the fibril growth with thioflavin T assay and atomic force microscopy (AFM). Fluorescent intensity increased as k-casein fibrils were formed and finally assembled fibrils were few hundreds of nanometers long. We analyzed the mechanical strength of the assembled fibrils with the AFM nano-indentation method. Assembled fibrils were found to have several GPa moduli comparable to naturally occurring strong materials such as collagen and silk. We fabricated stable hollow microcapsules by electrostatic interactions taking advantage of strong mechanical properties of the k-casein fibrils. Hollow microcapsules were successfully prepared due to both strong molecular interactions and mechanically strong k-casein fibrils.
BM11.03: Polysaccharide-Made Advanced Materials—Processing and Photonics
Monday PM, November 27, 2017
Sheraton, 2nd Floor, Liberty BC
1:45 PM - BM11.03.01
Hairy Nanocelluloses as Next Generation Threshold Antiscalants—Engineering Building Blocks of Plant Cell Walls to Regulate Crystallization
Amir Sheikhi 1 2 3 , Ashok Kakkar 1 3 , Theo van de Ven 1 2 3 Show Abstract
1 Chemistry, McGill University, Montreal, Quebec, Canada, 2 Pulp and Paper Research Centre, McGill University, Montreal, Quebec, Canada, 3 Quebec Centre for Advanced Materials, McGill University, Montreal, Quebec, Canada
Scales, sparingly soluble inorganic salts, are formed in aqueous systems with high levels of hardness and alkalinity. The precipitation and adsorption of scale in unit operations have turned into a major issue, imposing considerable operational and economic losses to industry. Current gold standard in scale prevention involves phosphonated macromolecules, which have raised a red flag due to environmental side effects, such as eutrophication. Here, we engineer the building blocks of trees, cellulose fibrils, at nanoscale to overcome the structural limitations of conventional nanocelluloses, and develop the first family of threshold nanocelluloses-based scale inhibitors with promising capability in inhibiting and modifying calcium carbonate, the most common type of scale. Carboxylic acid functionalized hairy nanocelluloses at ppm concentrations are able to completely prevent the calcium carbonate crystallization in electrochemically simulated harsh scaling conditions, where an additive-free system fully scales in less than 0.5 h. The nanostructure and chemistry of cellulose nanocrystals are investigated to shed light on the mechanism of scale inhibition, detailing the inevitable structural limitation of conventional nanocelluloses. The outcome of this research may translate into a sustainable, green solution for (i) the long-lasting scaling challenge of water-based industries, (ii) efficient design of inorganic-organic biomimetic nanocomposites, and (iii) improved solubility of sparingly soluble species based on the most abundant biopolymer in the world.
2:00 PM - *BM11.03.02
Bio-Inspired Photonic Structures with Biopolymers
Silvia Vignolini 1 Show Abstract
1 , University of Cambridge, Cambridge United Kingdom
From the most vivid and brilliant colors to the brightest whites, the optical appearance of living organisms rely on ordered, quasi-ordered or disordered structures with lattice constants or scattering element sizes on the order of the wavelength of visible light [1,2]. Mimicking such natural hierarchical architectures with biopolymers enables us to fabricate novel photonic structures using low cost materials in ambient conditions, answering the growing demand for optical interfaces and sensors required for biomedical applications, cosmetics, food and inks.
Here, I will discuss the diversity of photonic structures available through the self-assembly of nanocrystals of cellulose into either disordered networks  or hierarchical cholesteric structures; from films [4,5] to droplets  and in the presence of external magnetic fields .
 M Burresi, L Cortese, L Pattelli, M Kolle, P Vukusic, DS Wiersma, U Steiner, S Vignolini – Scientific reports (2014) 4, 7271
 BD Wilts, HM Whitney, BJ Glover, U Steiner, S Vignolini – Materials Today: Proceedings (2014) 1, 177
 S Caixeiro, M Peruzzo, OD Onelli, S Vignolini, R Sapienza – ACS Appl Mater Interfaces (2017) 9, 7885
 AG Dumanli, G Kamita, J Landman, H van der Kooij, BJ Glover, JJ Baumberg, U Steiner, S Vignolini – Adv Opt Mater (2014) 2, 646
 G Kamita, B Frka-Petesic, A Allard, M Dargaud, K King, AG Dumanli, S Vignolini – Advanced Optical Materials (2016) 4, 1950
 RM Parker, B Frka-Petesic, G Guidetti, G Kamita, G Consani, C Abell, S Vignolini –ACS Nano (2016) 10, 8443
 B Frka-Petesic, G Guidetti, G Kamita, S Vignolini – Adv Mater 2017 in press
2:30 PM - BM11.03.03
Light Responsive Nanocrystalline Cellulose Films and Microspheres
Junqi Wu 2 , Maddy Anthonisen 1 , Timothy Morse 3 , Monika Rak 3 , Peter Grutter 1 , Mark Andrews 2 Show Abstract
2 Chemistry, McGill University, Montreal, Quebec, Canada, 1 Physics, McGill University, Montreal, Quebec, Canada, 3 , Anomera Inc, Montreal, Quebec, Canada
Nanocrystalline cellulose (NCC) is a high aspect ratio, predominantly crystalline rod-like particle that has emerged as a leading sustainable resource “platform” with potential for broad spectrum applications in technology. Most research to date has focused on physical and chemical properties of the nanoparticle itself. In the present work, we describe studies of NCC that has been aggregated into films and microspheres. The purpose is to explore reversible and irreversible transport properties that are relevant to considerations of NCC as membrane filters, and as “addressible” photo-responsive host-guest delivery media. New properties emerge that depend on the pathway to produce films or microspheres. We demonstrate the principle of reversible “photo-locking” in NCC microspheres and films. Accordingly, NCC films and microspheres were prepared by covalent attachment of 7-coumaryl-(6-isocyanatohexyl) carbamate to the NCC building blocks. We establish that coumarin moiety undergoes reversible photodimerization that regulates the uptake/out-diffusion of methylene blue. We describe the adsorption kinetics and discuss various diffusion models relevant to the photolocking event. In situ AFM studies reveal how mechanical properties, like adhesion and elastic response of films and microspheres change with reversible photo-crosslinking.
2:45 PM - BM11.03.04
The Effect of Water on Rheology of Native Cellulose/Ionic Liquids Solutions
Behzad Nazari 1 2 , Indira Saifuddin 2 , Nyalaliska Utomo 2 , Sujyot Mony 2 , Ralph Colby 2 Show Abstract
1 , Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts, United States, 2 , The Pennsylvania State University, University Park, Pennsylvania, United States
Cellulose coagulates upon adding water to its solutions in ionic liquids. Although cellulose remains in solution with much higher water contents, here we report the effect of 0-3 wt.% water on solution rheology of cellulose in 1-butyl-3-methylimidazolium chloride (BMImCl) and 1-ethyl-3-methylimidazolium acetate (EMImAc). Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), and polarized light microscopy were also used to study water absorbance to the solutions. Tiny amounts of water (0.25 wt.%) can significantly affect the rheological properties of the solutions, imparting a yield stress, while dry solutions appear to be ordinary viscoelastic liquids. Annealing the solutions containing small amounts of water at 80°C for 20 minutes transforms the samples to the fully dissolved “dry” state. The yield stress grows linearly with water content and saturates at a level that increases with the square of cellulose content.
BM11.04: Biopolymer-Made Advanced Materials—Fabrication and Applications
Monday PM, November 27, 2017
Sheraton, 2nd Floor, Liberty BC
3:30 PM - *BM11.04.01
Making Smart Materials with Biosilica from Diatoms Microalgae
Gianluca Farinola 1 , Roberta Ragni 1 , Danilo Vona 1 , Gabriella Leone 1 2 , Marco Lo Presti 1 , Stefania Cicco 3 Show Abstract
1 , University degli Studi-Bari Aldo Moro, Bari Italy, 2 , Istituto Italiano di Tecnologia, Milano Italy, 3 , CNR ICCOM, Bari Italy
Diatoms are a large class of single-cell algae having their cells encased in microscopic three dimensional silica shells (frustules). The frustules are made of amorphous silica combined with organic molecules (e.g. long chain polyamines, silaffins, silacidins) and they are characterized by highly regular, porous, nanopatterned surfaces. The nanostructures’ design together with the chemical-physical properties of the biosilica determines the intriguing mechanical and photonic behavior of these structures.
The easy farming of diatoms and the manifold possibility of chemical modification of biosilica make it attractive as a low-cost source of mesoporous biomaterials for a variety of applications including biomedicine, photonics and sensing1.
The lecture will discuss examples of nanomaterials for different applications obtained in our laboratories by chemical modification of biosilica from diatoms microalgae.
Biosilica extracted from Thalassiosira weissflogii diatoms has been functionalized with 2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), an efficient scavenger of reactive oxygen species (ROS). Drug delivery of Ciprofloxacin, an antimicrobial against orthopedic implant-related infections, from the TEMPO-biosilica has been investigated. The TEMPO-biosilica, combining drug delivery with anti-oxidant properties, has been used as multifunctional substrate for osteoblast-like cells growth2.
With a different procedure, based on in vivo doping, incorporation of a bone regeneration enhancer (sodium alendronate) into the biosilica of Thalassiosira weissflogii has been achieved. Alendronate-doped biosilica enhances bone and stem cells growth and inhibits bone disruptors osteoclast cells.
In vivo doping has been also performed with several classes of light emitting molecules (fluorescent conjugated compounds3 or phosphorescent organometallic complexes) thus obtaining hybrid photonic structures.
Finally, hybrid nanostructures have been obtained by polymerization of dopamine on the purified and activated frustules’ surface.
Overall, our investigation points out at the combination of biotechnological production and chemical modification of diatoms' biosilica as a convenient route to the synthesis of functional nanostructured materials.
1. R. Ragni, S.R. Cicco, D. Vona, G. Leone, G. M. Farinola, J. Mater. Res. 2017, 32 (2), 279.
2. S. R. Cicco, D. Vona, E. De Giglio, S. Cometa, M. Mattioli Belmonte, F. Palumbo, R. Ragni, G. M. Farinola ChemPlusChem 2015, 80, 1063.
3. D. Vona, M. Lo Presti., S. R. Cicco, F. Palumbo, R. Ragni and G. M. Farinola, MRS Adv. 2016, 1(57), 3817.
4:00 PM - BM11.04.02
Modular and Robust Thread-Based Optical Sensors for the Next Generation of Wearables
Rachel Owyeung 1 , Muhammad Zeeshan 1 , Sameer Sonkusale 1 Show Abstract
1 , Tufts University, Medford, Massachusetts, United States
The detection of analytes present in the environment is essential for applications regarding health, food spoilage or allergens, and public and workplace safety. Popular techniques include electrochemical detection of analyte oxidation or an optical detection of chemically responsive materials . Both techniques have achieved high sensitivity and selectivity, though the vast range of applications prove a need for the continued research into operational advancements. These include equipment-free read out, training-free usage, and facile fabrication approaches that produces robust and reusable sensors. This will overall improve the affordability and ease of use to grant low resource communities access to these necessary technologies.
Threads have become popular substrates for low-cost diagnostic platforms and wearable technology advances. Like paper-based approaches, threads are flexible and have favorable wicking properties . Previously, our group has demonstrated paper-based approaches for environmental sensing studies . Contrastingly, threads offer a three-dimensional area for analytical measurements and have an added benefit of easier integration into smart clothing. As such, our group developed a toolkit of chemical and electrical sensing techniques using thread substrates . In this work, we differ from previous findings by demonstrating a stable entrapment of optically responsive dyes using polymer matrices chitosan and polydimethylsiloxane to move towards a detection system that can be integrated into clothing.
We have achieved a thread-based wearable sensor for the environmental monitoring of ammonia, ethanol, and pH changes from 4.4 to 7.6 that is able to withstand 6400 rpm in a centrifuge. We use a metalloporphyrin, 5,10,15,20-Tetraphenyl-21H,23H-porphine manganese(III) chloride, and two pH indicator dyes, methyl red and bromothymol blue, for a proof-of-concept. Our optical approach allows for chemical detection without expensive readout equipment. The threads are scanned using a smartphone and inexpensive LED microscope attachment for RGB value changes to determine the presence of an analyte. Notably, this design is modular; the type and quantity of dye molecules can be modified for a broader array of chemical sensing. These molecules are entrapped by our dual matrix to improve stability and robustness of the sensor. Chitosan is an abundant biopolymer that is water soluble at low pH values, allowing for matrix creation without the use of harsh solvents. It is also known to have bacteriostatic properties, making it ideal for wearable device applications . This facile fabrication and validation of a low-cost sensor that is highly stable is an ideal design for the next generation of textile and clothing technologies.
S. Lim et al. Nat Chem. 562-567(2009) 1
P. Mostafalu et al. Microsyst Nanoeng. 16039(2016) 2
Y. Chen et al. Biosens Bioelectron. 477-484(2015) 67
D. Raafat et al. Microb Biotechnol. 186-201(2009) 2
4:15 PM - BM11.04.03
Mechanical Properties of Cellulose Nanofibers (CNF) Reinforced Styrene Butadiene Rubber (SBR)
Masayuki Kawazoe 1 Show Abstract
1 , The Yokohama Rubber Co., Ltd., Hiratsuka Japan
Stress-strain and viscoelastic properties of SBR with CNF composite have been measured to discuss the reinforcement mechanism. It is generally said that the improvement of the mechanical properties of CNF reinforced SBR is poorer than the cases like natural rubber and nitrile rubber because of the mismatched polarity between the fiber and the rubber. Here, the possibility of the reinforcement for the unfavorable combination is the topic of the discussion. Most types of rubber used in tire industry are relatively nonpolar, and to find the solution for this matter is the key to expand the applicability of CNF for the industry. Actually, to meet the demand of large scale and high-speed transportation for the future agricultural machinery, much tougher rubber materials are required for highly durable agri-tires and CNF is one of the best candidates for the reinforcement fiber. This project is collaboration of academic and private sectors supported by Ministry of Agriculture, Forestry and Fisheries (MAFF) in Japan.
4:30 PM - BM11.04.04
Processing Agarose Films and Foams for Biomedical Applications
Joshua Kaufman 1 , Mishal Patel 1 , Alexander Cole 1 , Sean Moore 1 , Ayman Abouraddy 1 Show Abstract
1 , University of Central Florida, Orlando, Florida, United States
With applications ranging from food packaging to wound dressings to local drug delivery, polymeric films and coatings have been used in industry and investigated in the lab for decades. Processing techniques on well-chosen materials can yield mechanically stable films with a wide range of diffusion, degradation, and surface energy characteristics that are flexible enough to conform to most contours. Petroleum-based polymers such as the widely used and various PLGA species often require harsh chemicals to process which are difficult or impossible to completely remove, which is undesirable for applications in the food and medical industries. Furthermore, recent cultural shifts in environmental attitudes toward green, renewable materials may cause both consumers and investors to shy away from petroleum-based products. In light of these factors, we have developed a fabrication method for producing free-standing agarose films and gauze-like foams.
Agarose is the polysaccharide derived from certain forms of red algae whose gelatin agar is used ubiquitously in microbiology laboratories and even cooking. Our process begins by boiling agarose in water to completely dissolve it. It is then allowed to cool and solidify into a gel disk that is then placed under vacuum at room temperature until the gel is completely dehydrated, forming a flexible, sturdy, free-standing film. The diameter and thickness of the resulting film may be tuned by allowing the solution to gel in a larger beaker and adjusting the volume of the gel disk at the outset. Molds may be used to produce various shapes, and the films are easily cut by scissors or a razor blade to further alter the geometry. The mechanical properties may be tuned by adding polyethylene glycol (PEG) to the original solution, resulting in a film that is more flexible with more elongation under stress. Adding cargo is simply achieved by pipetting a small amount of aqueous solution containing the cargo to the gel before dehydration and allowing the gel to soak up the cargo in a sponge-like manner at room temperature. The release rate of the cargo is tunable by the introduction of the polysaccharide chitosan to the gel. We demonstrate this ability by altering the release rate of fluorescein into water from minutes to hours. Furthermore, multi-stage release is possible by producing multi-layered films, which is demonstrated through an experiment in which a quick burst of fluorescein is followed by slow, sustained release. Lastly, if the initial solution is instead slowly cooled while continuously stirred, the gel takes on the consistency of applesauce, which if dried under vacuum forms a porous foam. We demonstrate the ability to control the porosity of the foam by varying the speed of dehydration under vacuum. The same control over the release rate of cargo is demonstrated, as well as the additional benefit of better absorption of aqueous solutions than the dry gel films, for possible use as a drug-eluting gauze.
BM11.05: Poster Session I
Monday PM, November 27, 2017
Hynes, Level 1, Hall B
8:00 PM - BM11.05.01
Microscopic Analysis of Thermally Active Modes and Surface Free Energies of Peptide/2D Solid Hybrid Structures
Tyler Jorgenson 1 2 , David Starkebaum 2 , Mehmet Sarikaya 2 , Rene Overney 3 Show Abstract
1 Molecular Engineering and Science Institute, University of Washington, Seattle, Washington, United States, 2 GEMSEC, Materials Science and Engineering, University of Washington, Seattle, Washington, United States, 3 Chemical Engineering, University of Washington, Seattle, Washington, United States
Bio/nano-soft interfaces can be formed by the adsorption of biological or organic molecules onto atomically flat substrates. The transport properties of these hybrid structures can be affected by: (1) The adhesive coupling between the bio/organic moieties and the inorganic substrate; (2) The molecular conformations and overall structure of the assembly; and (3) The mobility of the molecules within the adsorbed molecular assembly. Interfacial and surface free energies, as well as thermal active modes, such as relaxation and interaction modes, provide fundamental insight into these molecular mobilities, conformations, and interactions between molecular self-assemblies and atomically flat solid substrates. We utilize a local probing technique called "intrinsic friction analysis" (IFA). This technique utilizes the mechanical scattering process between a sliding scanning force microscopy (SFM) tip in contact with the thermal active modes of the scanned sample to investigate molecular modes of dissipation and relaxation processes associated with conformational changes. The IFA technique allows for the determination of thermal modes and interfacial forces via an energetic analysis based on the time-temperature superposition principle. In this work, the hybrid structures are formed by the spontaneous assembly of experimentally selected and rationally designed solid binding dodecapeptides (SBPs) on 2D solids. SBPs have highly variable conformational structures on a given substrate that can be tailored via point and domain amino acid mutations. This can lead to the formation of amorphous (non-ordered) or crystalline (ordered) molecular assemblies. The use of these self-assembling peptides, therefore, provides a platform to study energetics of the rotational and translational modes on the substrate surfaces. The studies carried out with the crystalline and amorphous peptide assemblies on the surfaces have activation energies of approximately 25 and 23 kcal/mol respectively, while the friction coefficients are 0.15 and 0.35 at 1 µm/s at 25°C and relative humidity of less than 4%. The unstructured peptide assembly has a fractal dimension of 2.2 while the structured peptide assembly has 2 dimensional behavior. Additionally, the energetics of surface binding and mobility are affected when the solid substrate is reduced to a single layer, which in turn affects the dynamics of the assembled structures. Therefore, we extended these initial studies by examining SBPs on 2D substrates such as graphene, MoS2, and BN. A general criteria between the peptide sequences and the structural characteristics of the 2D substrates will be discussed towards developing biofunctional 2D solid-state devices. The research is supported by the funds, NSF-DMR-1629071, through the MGI Program (Materials Genome Initiative).
8:00 PM - BM11.05.02
The Self-Assembly of Graphene Oxide and Nanocellulose
Rui Xiong 1 , Lijuan Zhang 1 , Vladimir Tsukruk 1 Show Abstract
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Establishing deeply understanding and precise control over the interaction between graphene and natural polymer is critically important for the fabrication of graphene bionanocomposite with novel nanostructure, mechanical-robustness and multifunctionalities. One dimensional (1D) nanocellulose, as a new emerging family of cellulose, are drawing increasing attention due to its renewable, biocompatible, high strength, low-cost and high surface modification efficiency. Here we report a unique self-assembled graphene nanostructure by carefully tailored the experimental condition of graphene oxide and nanocellulose. We deeply characterized and analyzed the self-assembly mechanism behind the unusual phenomenon. Additionally, this self-assembled GO/nanocellulose nanocomposites demonstrate mechanical enhancement and unique wetting ability, which are attractive in the applications of nanofiltration and sensors.
8:00 PM - BM11.05.03
Extraction of Pectin and Characterization of Pectin Films from Ripe Plantain Peel
Chizoba Obele 1 , Ofoegbu Stanley 2 , Chioma Awuzie 3 Show Abstract
1 , Nnamdi Azikiwe University, Awka, Awka Nigeria, 2 , Department of Materials and Ceramic Engineering, CICECO-Aveiro Institute of Materials, University of Aveiro, Campus Universitario de Santiago, Aveiro Portugal, 3 , Department of Science Laboratory Technology, Federal Polytechnic, Oko Nigeria
The extraction of pectin from plantain peel was achieved using acid extraction method. The yield was 40.5% while the moisture content was 87.56%. The degree of esterification was found to be 59.53% hence the pectin is categorized as high methoxyl pectin (DE≥50%). The equivalent weight was found to be low (1000g/ml) while the galacturonic acid content was 2.89mg/ml. The extracted pectin was used with polyvinyl alcohol (PVA) to synthesize a composite polymer film with and without glycerol as a plasticizer. Introduction of glycerol as plasticizer was observed to lead to improvements in mechanical properties of the composite film. The best mechanical properties of the polymer film; tensile strength, % elongation and abrasion resistance of 5.51 MPa, 5.75% and 1.44 ×105 cm2 respectively were obtained with 10ml glycerol/ 1g pectin. Raman spectra showed peaks at 2930 cm-1, 1750cm-1 and 820 cm-1 indicating CH- strech, C=O ester group of pectin and COH ring in pectin respectively. Thermal analysis of the composite films indicates partial decomposition in a single stage between 220-270 oC for plantain in argon which is in line with that obtained for citrus pectin in argon (200-230oC). Since the major composite film, pectin is sourced from waste, the synthesized films are considered as a potential source of renewable and environmentally benigh packaging material for the food and packaging industry.
8:00 PM - BM11.05.04
Effective and Selective Recovery of Palladium Ions from Wastewater Using Wool Keratin Resin
Naohisa Gando 1 , Shinji Hirai 2 , Toshihiro Kuzuya 2 , Tomokazu Ise 3 Show Abstract
1 Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido, Japan, 2 Research Center for Environmentally Friendly Materials Engineering, Muroran Institute of Technology, Muroran, Hokkaido, Japan, 3 Research and Development, The Japan Wool Textile Co., Ltd., Kakogawa, Hyogo, Japan
An eggshell membrane and feather are considered to be strong candidates for an absorbent to recover precious metals from a wastewater. Maruyama et al. have investigated the recovery of precious metals such as Au, Pd and Pt from a wastewater by using an eggshell membrane. Their report revealed that an eggshell membrane could serve as an excellent absorbent for Au ion . Our research group has investigated the fabrication process and utility of a keratin resin. Disulfide, carboxyl and amine group contained in a keratin exhibit a strong affinity for Au and platinum group metals. Also, high resistance for acidic condition and high water absorbency of keratin resin enable us to use a metal absorbent for acidic wastewater containing valuable metals. In our previous work, a keratin resin obtained by applying a heating pressurization of woven wool fabrics was used as an absorbent to recover precious metals. A keratin resin was examined in 2 %HNO3 solution containing Au, Hf, Ir, Pd, Rh, Ru, Sb, Sn, and Te ion (each 10 ppm). A keratin resin could not serve as absorbent for Hf, Ir, Pd, Rh, Ru, Sb, and Sn ion. On the other hand, the absorption ratios of Au and Pd ion attained 55 and 30 % at 24 hours. The aim of this study was to confirm the selective recovery of Pd from the acid wastewater containing Pd and other valuable metals. In order to fabricate a keratin resin, Merino woven wool fabrics were cut out into the round shape with a diameter of φ20 mm. Then, cut wool fabrics were filled into the stainless jig (φ20 mm) and resinified by using a hot press at a pressure of 15 MPa and a temperature of 100-150 degrees Celsius. The simulated wastewaters were prepared by mixing the solution of Pd(NO3)2 (1M HNO3) and Cu(NO3) 2 (0.1M HNO3). Keratin resins and woven wool fabrics were soaked into the simulated wastewater at 100g/L of solid/solution ratio and were retained for 8 ~ 24 hours at a room temperature with stirring. The Pd and Cu ion concentrations in simulated wastewaters after soaking was measured by Inductively Coupled Plasma Atomic Emission Spectroscopy.
When wool fabric was soaked in the wastewater containing 250 ppm of Pd and 750 ppm of Cu, the recovery ratios of Pd and Cu were 95 and 1 % at 8 hours. At 24 hours, the recovery ratio of Cu attained 66 %. On the other hand, in the case of keratin resins, the recovery ratios of Pd and Cu were 53 and 0 %, respectively, at 8 hours. Though the recovery ratio of Pd attained 78 at 24 hours, Cu ion was not absorbed. Our results indicate that a keratin resin can be used for a selective absorbent to separate Pd ion from a mixture solution of Pd and Cu. Additionally, when the same fabrics or resins were soaked into the high concentration simulated wastewater (10000 ppm of Pd and 8400 ppm of Cu), a keratin resin exhibited an excellent ability to separate Pd ion from a wastewater.
T. Maruyama, Y. Terashima, S. Takeda, F. Okazaki, and M. Goto, Process Biochem, 2014, 49, 850-857.
8:00 PM - BM11.05.05
Antibacterial Properties of Woven Fabrics Absorbing Rare Earth Ions and Their ESR Measurements
Kenta Iijima 1 , Shinji Hirai 2 , Hiromi Kameya 3 , Hideki Oomori 4 , Eiji Nakamura 5 Show Abstract
1 , Graduate School of Engineering, Muroran Institute of Technology, Muroran Japan, 2 Research Center for Environmentally Friendly Materials Engineering, Muroran Institute of Technology, Muroran Japan, 3 , National Agriculture and Food Research Organization, Tsukuba Japan, 4 , The Japan Wool Textile Co., Ltd, Kakogawa Japan, 5 , Santoku Corporation, Koube Japan
The woven wool fabric that absorbed Ce3+ exhibited an antibacterial property much stronger than that of cotton fabrics absorbing silver nanoparticles. In this study, antibacterial effect of woven wool fabrics that absorbed La3+, Gd3+, and Ce3+ on Staphylococcus aureus have been investigated. Instead of woven wool fabric, cotton, silk, and polyester fabric were also examined. The antibacterial effect of Ce3+ is considered to be due to the generation of hydroxyl radical (●OH) by Fenton reaction. Therefore, in order to elucidate its detailed mechanism, ESR measurement was conducted using spin trapping method.
Wools, silks, and cotton fabrics were soaked in the solutions of Ce nitrate, La nitrate, and Gd nitrate at 80°C, the mass ratio of 1:100, and retained with magnetic stirring for two hours. Then, fabrics were sufficiently washed with distilled water and then dried at ambient atmosphere. For antibacterial effect evaluation, the fabric samples were sterilized in an autoclave and inoculated with the test liquid of Staphylococcus aureus. Then fabric samples were kept in a darkroom for cultivation for 18 hours. They were washed and separated from the bacteria, to quantify the number of them in the washing-out solution by using the pour plate culture method. The antibacterial activity value was calculated using the following equation.
Antibacterial activity value =｛log(Examined fabric : Viable bacteria count after culture)－log(Examined fabric : Viable bacteria count just after inoculation)｝－｛log(Examined fabric : Viable bacteria count after culture)－log(Examined fabric : Viable bacteria count just after inoculation)｝
The ESR measurement was conducted by submerging each fabric sample in aqueous hydrogen peroxide at the mass ratio of 1:15, and retained for 30 minutes at a temperature of 25°C. Then, the sample was combined with a spin trapping agent i.e. CYPMPO（5-(2,2- dimethyl-1,3-propoxy cyclo phosphoryl)-5-methyl-1- pyrroline N-oxide）.
The antibacterial activity values of woven wool fabrics that absorped Ce3+, La3+, and Gd3+ were showed to be 5.8, 5.9, and 5.9, respectively, indicating that Ce3+, La3+ and Gd3+ adsorbed woven wool fabrics exhibit an excellent antibacterial effect. Then the antibacterial effects of cheapest Ce3+ were examined with using cotton, silk, and polyester fabrics. The antibacterial activities for cotton, silk, and polyester fabrics were showed to be 5.2, 5.8, and 2.2.
Relatively low antibacterial effect for polyester fabric is attributed to the fact that polyester fabric cannot absorb Ce3+.
ESR results of woven wool fabric without Ce3+ exhibited only a peak resulting from manganese marker. ESR spectrum of woven wool fabric with Ce3+ had a peak resulting from ●OH, which provided evidence for the formation of ●OH.
8:00 PM - BM11.05.06
Antibacterial Silver Nanowire-Chitosan Nanocomposite Films
Doga Doganay 1 , Suleyman Somek 1 , Dilara Aydin 2 , Akin Kanicioglu 3 , Sahin Coskun 1 , Sevda Senel 2 , Gulcin Akca 3 , Husnu Unalan 1 Show Abstract
1 Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara Turkey, 2 Department of Pharmaceutical Technology, Hacettepe University, Ankara Turkey, 3 Department of Medical Microbiology, Gazi University, Ankara Turkey
Production of biopolymers and their nanocomposites received considerable interest primarily due to biomedical purposes and also due to the scarcity of petroleum resources and environmental concerns. Amongst the biopolymers, chitosan has great potential to be used in biomedical applications because of its biocompatibility and biodegradability properties as well as it antimicrobial activity. Different nanocomposite technology using structures such as nanotubes and graphene have been investigated to improve the mechanical, electrical and thermal properties of chitosan. In this work, different amount of polyol synthesized silver nanowires (Ag NWs) were used to fabricate antibacterial and electrically conductive nanocomposites. AgNWs were incorporated into chitosan gel and nanocomposite films were prepared using solvent casting method. Thermal behavior of nanocomposite films were investigated using differential scanning calorimetery and the morphology of the nanocomposites was studied using scanning electron microscopy. A swagelok cell was used to measure electrical resistivity of the films along their thickness. Percolation threshold was measured as 0.20 vol. %. Antibacterial activity of the nanocomposite films against Staphylococcus aureus (gram positive coccus), Escherichia coli (gram negative basil), Streptococcus pyogenes (gram positive coccus) and Bacillus cereus (gram positivebacil) were investigated using disk diffusion method. The developed AgNW-chitoan composites were observed to show higher antibacterial activity than bare chitosan films against the tested strains. These results revealed the high potential of the Ag NW/chitosan nanocomposites to be used as antibacterial product.
8:00 PM - BM11.05.07
3D Printed Antibacterial Ag NW/PLA Nanocomposites
Ipek Bayraktar 1 , Doga Doganay 1 , Sahin Coskun 1 , Akin Kanicioglu 2 , Gulcin Akca 2 , Husnu Unalan 1 Show Abstract
1 Department of Metallurgical and Materials Engineering, Middle East Technical University, Ankara Turkey, 2 Department of Medical Microbiology, Gazi University, Ankara Turkey
3D printing technology has become one of the most important manufacturing technologies since its invention and predicted to grow continuously in the years ahead. 3D printing is generally based on polymeric materials due to their ease of processing. The most widely used polymer ink is biodegradable polylactide (PLA). PLA based nanocomposite materials are just started to be studied in 3D printing in order to add functionality to bare PLA. In this work, silver nanowires (AgNW’s) are used as a novel nanofilles to impart antibacterial activity to 3D printed PLA. Ag NWs are synthesized by polyol method and PLA based nanocomposites are prepared by a simple solution blending method. Then, Ag NW/PLA nanocomposites are extruded to obtain filaments with 1.75 mm diameter and testing samples are printed using fabricated filaments in a commercial 3D printer. Antibacterial properties of Ag NW/PLA nanocomposites are investigated against different standard bacterial strains of American Type Culture Collection (ATCC) by using conventional microbiological methods. Ag NW based PLA nanocomposites are found to have high antibacterial effect against both Staphylococcus aureus ATCC#25923 (Gram positive bacteria) and Escherichia coli (ATCC#25922) (Gram negative bacteria). Nanocomposites with higher silver loading showed better results; yet small amount of silver addition to PLA could be enough for nanocomposites to show reasonable antibacterial performance at low cost.
8:00 PM - BM11.05.09
The Pigment Eumelanin—A Biomaterial for the Enhancement of UV-Absorption of Plastic Films
Eduardo Di Mauro 1 , Richard Silverwood 1 , Abdellah Ajji 1 , Clara Santato 1 Show Abstract
1 , Polytechnique Montreal, Montreal, Quebec, Canada
Reducing greenhouse gas emissions and decreasing the amount of waste materials in landfills are two current challenges of the scientific community, with two of the main solutions identified being the replacement of plastic materials made from non-renewable resources with bio-based and biodegradable materials. Materials for food packaging and food service are concerned in such effort, too .
Organic and inorganic additives are used to enhance the functional properties (e.g. oxidation stability) of packaging materials . A key aspect of the packaging science and engineering entails understanding the food UV-radiation exposure in the end-use or storage environments, and, consequently, reducing the resulting UV-radiation induced damage .
Eumelanins are a dark-brown subclass of the melanins, biopolymers ubiquitous in animals and plants . Important properties of melanin are metal ion chelation , biocompatibility , mixed ionic-electronic conduction and photoprotection . In particular, a monotonic featureless absorption from the ultraviolet to the near-infrared (NIR) is the peculiar characteristics of eumelanin’s spectrum . Exploiting its excellent photoprotection properties, we herein report on the novel possibility of using eumelanin as a UV-absorption enhancer for packaging films (biodegradable and non-biodegradable). Three types of biodegradable polymers were combined in a batch mixer with eumelanin: poly(lactic acid) (PLA), polybutyrate-adipate-terephtalate (PBAT), as well as polycaprolactone (PCL); non-biodegradable plastics massively used in the market (not necessarily only for packaging), such as polyethylene (PE) and polypropylene (PP), were tested, too. They all entail processing temperatures that would preserve the pigment’s properties. The packaging films were obtained by thermoforming in a press, and the pigment was added in different weigh percentages (0.1, 0.5 and 1% wt.). Synthetic melanin (commercial Sigma and non-commercial DHI-melanin, DHICA-melanin) or natural (extracted from the ink sac of a cuttlefish) were exploited. The UV-absorption was measured for the plastic films (with and without the several types of melanin in different percentages), and the performance with respect to conventional synthetic UV absorbers (benzophenone and benzotriazole based) was evaluated. The pigment biodegradability in composting conditions, following the standard ASTM D5338, is currently being evaluated. Our research represents a further step towards achieving the enhancement of plastics’ functional properties with natural additives.
V. Siracusa et al., Trends Food Sci. Technol., 19, 12, 634–643, 2008;A. Sorrentino et al.,Trends Food Sci. Technol., 18, 2, 84–95, 2007;L. K. Krehula et al., Polym. Bull., 2016; M. d’Ischia et al., Pigm Cell Melanoma R, 26, 5, 616–633, 2013;J. Wuensche et al., Adv. Funct. Mater., 23, 45, 5591–5598, 2013;C. J. Bettinger et al., Biomaterials, 30, 17, 3050–3057, 2009
8:00 PM - BM11.05.10
Mechanisms of Binding and Surface Diffusion of Engineered Peptides on Graphene Probed by Computational Modeling
Sefa Dag 1 , Mehmet Sarikaya 1 Show Abstract
1 GEMSEC and Mater Science and Engineering, Univ of Washington, Seattle, Washington, United States
Solid binding peptides are becoming fundamental biomolecular building blocks in a wide range of technology implementations at the molecular and nanometer-scales. Despite their widespread utility, a detailed understanding of binding, diffusion and self-assembly of peptides on solid materials is still lacking. In particular, solid binding peptides (SBPs) can be of major significance as versatile biomolecules in bridging biology and two-dimensional solids. Recent experimental observations in our lab show that combinatorially-selected engineered graphite-binding peptides assemble to form long range ordered nanostructures on graphite forming commensurate surface nanostructures. This highly potent hybrid of two simple entities, a short peptide and an atomic single layer, is an ideal system for modeling, e.g., through molecular dynamics. Therefore, we carried out systematic simulations to study the mechanisms of conformational binding and surface self-diffusion of solid-specific peptides on graphene. The work herein discusses structural and dynamic characteristics of peptides studied by using classical molecular dynamics (CMD) simulations in an aqueous environment on graphene. We determine the adsorption free energy and diffusion constant of the selected graphite-binding peptide (GrBP5-WT) with the amino acid sequence of IMVTESSDYSSY as well as three separate mutants; GrBP-M1, M2 and M3 with anchoring domain ASSA, WSSW, and FSSF, respectively. Particular attention, therefore, is paid to the specific role of these point mutations to the anchoring domain, the structural motif that stabilizes the peptide on graphene through molecular recognition of the solid’s surface lattice. Our conformational free energy model, examined at room temperature, shows that GrBP5-M2 has the strongest affinity to graphene among the variants studied. These findings are consistent with the experimental results. Additionally, we show that there is a strong correlation between diffusion rates and the adsorption strengths of the peptides. Finally, we demonstrate the specific role of diffusion in the spontaneous organization of long-range ordered peptide nanostructures on graphene surface. We thank C. R So for supplying the experimental results. The research is supported by the funds, NSF-DMR-1629071, through the MGI Program (Materials Genome Initiative).
8:00 PM - BM11.05.11
Nanomechanical Testing of Nanocomposite PCL Scaffolds and Fibers
Panagiota Gkertsiou 1 , Zoe Dardani 1 , Spyridon Kassavetis 1 , Christina Kamaraki 1 , Christoforos Gravalidis 1 , Varvara Karagkiozaki 1 , Stergios Logothetidis 1 Show Abstract
1 Physics Department, Nanotechnology Lab LTFN, Aristotle University of Thessaloniki, Thessaloniki Greece
By virtue of its physical properties, biodegradability and low cost, polycaprolactone (PCL) is gaining popularity for fabrication of scaffolds, with various applications such as drug release, tissue engineering and antimicrobial surfaces. The scaffolds nanomechanical characterization is critical for understanding their mechanical performance and cell / bacteria adhesion and colonisation.
In this study, nanocomposite PCL scaffolds with embedded ZnO nanoparticles (NPs) were developed by electrospinning for antibacterial applications. The effect of the ZnO NPs on the mechanical properties of the PCL scaffolds and individual fibers, 1.2-1.7 μm in diameter, was examined thoroughly by Nanoindentation Continuous Stiffness Measurements (NI) and Atomic Force Microscopy (AFM). In NI, a Berkovich type diamond indenter (three-sided pyramid) was used to deform the PCL scaffolds and fibers and to study their resistance to point/axial loading. The maximum penetration depth in all the NI experiments was 100 nm, 1/10 approximately of the fibers diameter.
X-ray diffraction characterization showed the addition of 1% w/v ZnO NPs results to more crystalline PCL fibers, while the Elastic Modulus, calculated after analysis of the NI Load-Displacement curves, increases from 1.2 GPa (pristine PCL) to 1.7 GPa, whereas the hardness values is almost the same (0.7 GPa). In addition, AFM was used to deform the nanocomposite fibers and to locate the critical load for the plastic deformation initiation, which decreases from 1.25 μΝ to 1.07 μΝ after the addition of the ZnO NPs. The adhesion of the nanocomposite PCL:ZnO(NPs) fibers to their substrate was also tested by AFM and it was found that although the fibers are distorted plastically, they remain adhered on the substrate. In conclusion, the incorporation of ZnO NPs into PCL fibers affects the crystallinity and the nanomechanical properties of the nanocomposite scaffolds and fibers.
Benedetto Marelli, Massachusetts Institute of Technology
Fiorenzo Omenetto, Tufts University
Jelena Rnjak-Kovacina, University of New South Wales
Hu Tao, The University of Texas at Austin
Shanghai Runshuo Medical Instrument Co., Ltd.
BM11.06: Structural Biopolymers for Regenerative Medicine and Drug Release
Tuesday AM, November 28, 2017
Sheraton, 2nd Floor, Liberty BC
8:15 AM - BM11.06.01
Controlled Release Behavior of a Hydrophilic Drug from Electrospun Amyloid-Like Protein Blend Nanofibers
Ahmet Meydan 1 , Gözde Kabay 1 , Gizem Kaleli Can 1 , Mehmet Mutlu 1 Show Abstract
1 , TOBB University of Economics and Technology, Ankara Turkey
In this study, a controlled drug release platform from natural amyloid-like (AL) protein, bovine serum albumin (AL-BSA) with ampicillin sodium salt (ASS) was developed. Towards accomplishing this target, 5%, 10% and 20% (w/w) ratios of ASS:AL-BSA blends were performed in an electrospinning system corresponding to ultrathin homogeneous nanofibers with an average diameter of 132±69 nm, 159±60 nm and 179±42 nm, respectively. Fourier transform infrared spectroscopy demonstrated that AL-BSA could capable of entrapping large amount of drug inside of nanofibers, which was attributed to the antimicrobial activity of the released drug against Escherichia coli and Staphylococcus aureus. Amount of released drug was measured by using UV-VIS spectrophotometer. The nanofibrous matrix of the electrospun membrane was shown a controlled release behavior of the drug for all ratios of ASS:AL-BSA. The transport mechanism was Fickian for the low ratio of ASS:AL-BSA (5% w/w). However, non-Fickian transport mechanism was observed at high ratios of ASS:BSA (>10% w/w) which was attributed to relatively longer path to the fiber surface due to the larger fiber diameter and non-homogeneous distribution of drug in the matrix as well as high standard deviation of nanofiber distribution. The results were demonstrated that single electrospinning of hydrophilic drugs with natural polymers could potentially be used for controlled release. The core and shell formation of electrospun nanofibers with the same kind of matrices and drugs are still under investigation.
8:30 AM - BM11.06.02
Multiscale Design and Synthesis of Biomimetic Gradient Protein/Biosilica Composites for Osteochondral Regeneration
Jin Guo 1 , Chunmei Li 1 , Shengjie Ling 1 2 , David Kaplan 1 Show Abstract
1 , Tufts University, Medford, Massachusetts, United States, 2 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Continuous gradients present at osteochondral interfaces, reflect complex tissue functions and involve changes in extracellular matrix compositions, cell types and mechanical properties. New and versatile biomaterial strategies are needed to better recapitulate these interfaces to optimize osteochondral tissue repair and regeneration. Silk protein-based composites, coupled with selective peptides with mineralization domains, were utilized to mimic the soft-to-hard transition in osteochondral interfaces. The 3D gradient composites were developed through integration of enzymatically triggered protein gelation and R5 peptide-induced gradient silicification. The gradient distribution of the mineralization domains allows for tunable control over the morphology, self-assembly and distribution of biosilica particles and ultimately the regulation of the mechanical and structural properties and architecture of the gradient composites. This composite system offers continuous transitions in terms of composition, structure and mechanical properties, as well as cytocompatibility and biodegradability. The gradient mineralized silk-based composites promoted and regulated osteogenic and chondrogenic differentiation of human mesenchymal stem cells in vitro respectively. The cells differentiated along the composites towards osteogenic lineage in a manner consistent with the R5-gradient profile. In chondrogenic conditions, formation of lacunae-like ECM around round chondrocyte-like cells was observed in the region with low extent of mineralization in the gradient composites. Such composite materials can be used to study the growth of natural tissues and the processes of regeneration, but also to act as tissue engineering constructs in vitro and in vivo, such as for osteochondral plugs. The system can be scaled to match the dimensions of osteochondral defects. Importantly, the incorporation of biosilicification domains into the biocompatible silk substrates under mild (peptide-mediated) conditions provides other potential applications such as the encapsulation of biomolecules which are sensitive to heat or caustic chemicals. This novel gradient biomaterial design offers a useful approach to meet a broad range of needs in regenerative medicine involving osteochondral tissue engineering.
8:45 AM - BM11.06.03
Functional Peptides for Biomedical Applications
Xianzheng Zhang 1 Show Abstract
1 , Wuhan University, Wuhan China
It is recognized that drug and gene delivery systems have numerous advantages for controlled drug release, including prolonged duration time, reduced side effect, improved drug bioactivity and enhanced therapeutic efficiency. To enhance the bioavailability of therapeutics and to deliver therapeutic agents to particular tissues and cells, the ideal drug and gene delivery systems should have desired functional properties, including target ability and stimuli responsibility. Our studies focused on the functional peptides for biomedical applications. For example, various targeting peptides were used for targeted drug/gene delivery. Enzyme sensitive peptide was used to give the delivery systems with protease responsibility. To achieve enhanced synergy effects, double/multiple stimuli-responsive systems have also been developed. The physical/chemical properties and drug/gene delivery behaviors in vitro or in vivo of peptide based delivery systems were investigated in detail. The results showed the drug and gene delivery systems exhibited improved drug controlled release and enhanced gene transfection efficiency.
 Wang XQ, Gao F, Zhang XZ.* Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201703159
 Chen WH, Luo GF, Lei Q, Hong S, Qiu WX, Liu LH, Cheng SX, Zhang XZ.* ACS Nano 2017, 11, 1419-1431.
 Zheng DW, Lei Q, Zhu JY, Fan JX, Li CX, Li C, Xu ZS, Cheng SX, Zhang XZ.* Nano Lett. 2017, 17, 284-291.
 Zheng DW, Li B, Li CX, Fan JX, Lei Q, Li C, Xu ZS, Zhang XZ.* ACS Nano 2016, 10, 8715-8722.
 Zhang J, Yuan ZF, Wang Y, Chen WH, Luo GF, Cheng SX, Zhuo RX, Zhang XZ.* J. Am. Chem. Soc. 2013, 135, 5068-5073.
9:00 AM - *BM11.06.04
3D Conducting Polymer-Biopolymer Scaffolds for Hosting and Monitoring Cells
Roisin Owens 1 2 Show Abstract
1 , Ecole des Mines-St. Etienne, Gardanne France, 2 Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge United Kingdom
My research program focuses on harnessing the power of engineering for developing in vitro biological models in a synthetic biology approach. By developing both the biological model and the adapted monitoring methods in parallel, both may be iteratively improved resulting in enhanced systems. I define the latter combination as in vitro systems: an integrated system to monitor human biology in vitro. Specifically, I have focused on the use of polymeric electroactive materials and devices which bridge a gap between hard inflexible materials used for physical transducers and soft, compliant biological tissues. The transducer thus becomes a ‘synthetic’ part of the model, allowing transduction and/ or stimulation of biological systems in the least invasive and thus most biomimetic fashion possible.
In this presentation I will discuss our recent progress in adding to the repertoire of tissue engineers; alongside the well-known biochemical and mechanical cues used to recreate biologically relevant tissues, we attempt to integrate electrical cues. Electrical cues have a demonstrated role in development, not just for electrogenic tissues, but for all tissues. To enable the trifecta of stimuli necessary for recreating tissues in vitro, we have generated conducting polymer scaffolds blended with biopolymers such as collagen. I will show evidence that these structures can simultaneously host and monitor tissues.
9:30 AM - BM11.06.05
Bicomponent Nanofibrous Tissue Engineering Scaffolds for the Dual Release of Biomacromolecules and Anti-Cancer Drug
Yu Zhou 1 , Natasha L.Y. Tsai 1 , Min Wang 1 Show Abstract
1 Department of Mechanical Engineering, The University of Hong Kong, Hong Kong Hong Kong
Cancer is a major cause for human deaths. At present, surgical removal is a primary treatment for solid and isolated tumors for cancer patients. However, functional disorders are common after tissue removal. Scaffold-based tissue engineering promotes tissue regeneration at the surgical site. Biomacromolecules such as growth factors can influence cell attachment, proliferation, differentiation and migration. Growth factors can be encapsulated in electrospun nanofibrous scaffolds and subsequently released to enhance tissue regeneration. The recurrence of cancer after surgery is another major issue. Anti-cancer drug may also be contained in electrospun scaffolds for treating cancer recurrence. In this study, different types of delivery vehicles were investigated for the dual delivery of biomacromolecules and anti-cancer drug for both regenerating body tissue and treating cancer recurrence. Bovine serum albumin (BSA) and doxorubicin hydrochloride (DOX) were used as model biomacromolecules and drug. Using dual-source-dual-power (DSDP) electrospinning, novel bicomponent fibrous scaffolds were made as dual delivery vehicles. BSA and DOX were encapsulated in PLGA50/50 nanofibers and PLGA75/25 nanofibers, respectively. The bicomponent scaffolds were made by either DSDP blend electrospinning or DSDP emulsion electrospinning. The morphology and structure of these scaffolds were studied using SEM and TEM. The encapsulation efficiency and in vitro release behavior of BSA and DOX were investigated. BSA and DOX encapsulated in scaffolds by different electrospinning techniques exhibited different encapsulation efficiencies and release behaviors. BSA and DOX in emulsion electrospun scaffolds showed higher encapsulation efficiency. Severe burst release of BSA and DOX from scaffolds made by blend electrospinning was observed. BSA and DOX from emulsion electrospun scaffolds showed slight burst release in the initial 24 hours. More sustained and controlled release of BSA and DOX from emulsion electrospun scaffolds was subsequently observed. Another type of bicomponent scaffolds were also made for the dual release investigations: BSA was encapsulated in PLGA50/50 nanofibers and DOX was encapsulated in PLGA75/25 microspheres. These bicomponent scaffolds were made by either DSDP blend electrospinning and electrospray or DSDP emulsion electrospinning and electrospray. Burst release was observed for blend electrospun fibers and blend electrosprayed microspheres. Both BSA and DOX release from bicomponent scaffolds made by DSDP emulsion electrospinning and electrospray exhibited limited initial burst release which was followed by sustained release. This study demonstrates that controlled dual release of biomacromolecules and anti-cancer drug could be achieved using electrospun fibrous scaffolds. It also shows that the release behaviours could be influenced by the scaffold fabrication method and design of delivery vehicles.
9:45 AM - BM11.06.06
Nanomechanics of pH Responsive, Drug-Loaded Polymer Grafts
Prathima Nalam 1 , Hyun-Su Lee 2 , Robert Carpick 2 , David Eckmann 2 , Russell Composto 2 Show Abstract
1 , State University of New York at Buffalo, Buffalo, New York, United States, 2 , University of Pennsylvania, Philadelphia, Pennsylvania, United States
Soft polymeric films are finding numerous applications in areas including healthcare delivery, environmental purification systems, energy storage systems and as well tribology. The ability of polymers to present a wide range of tunable functional and structural properties through alterations in chemical structure of the monomer or their environmental conditions, which otherwise is rarely possible with other hard materials, make them promising structural elements for such applications. Stimuli-responsive polymers in particular, when used as surface modification coatings for biomedical implants via end-grafted or self-adsorbed polymeric films, enhance the biocompatibility and enable controlled release of therapeutic drugs at the infected sites. In this study, we consider complementary architectures of polyelectrolyte films to develop structurally-enhanced anti-bacterial platforms. The films consist of a bilayer architecture where a thin (~ 10 nm) chitosan layer (CH) is grafted on top of poly(acrylic acid) (PAA) brushes (CH/PAA). The swollen PAA brushes are capable of holding antibiotics at neutral pH. When a bacterial infection develops (reducing the pH to 4.0), the PAA brushes collapse as the CH top layer swells to release the entrapped antibiotics into the environment1. Along with this antibacterial performance, the nanomechanical properties for the bi-layered polymer grafts at pH 7.4 and 4.0 is studied using atomic force microscopy (AFM)2. The surface interactions between polymer grafts and a negatively-charged silica microcolloid attached to the AFM cantilever are chosen to be representative interactions between the antibacterial coating and a bacteria/biofilm. The bi-layered structure of CH/PAA showed significant reduction in adhesive interactions in comparison to pure CH (by 97 %), but higher interactions in comparison to PAA films (~ 90%). Upon grafting CH over the PAA brushes, the normal stiffness was increased by 10-fold at pH 7.4 and 20-fold at pH 4.0 compared to PAA. Notably, the addition of multi-cationic Tobramycin (TOB), an antibiotic drug, further enhances the mechanical stiffness of the antibacterial coatings. The co-nonsolvancy effect leads to a competition between TOB and water molecules for the PAA chains resulting in altered hydration and enhanced mechanical properties for PAA (by ~ 53 %) and CH/PAA films (~ 75%). The enhanced stiffness of the bilayered structures is desirable to build reliable soft platforms and that the potential of the bilayer to swell and release biocidal drugs in response to a pH reduction is ideal for preventing any localized infection. The bacterial proliferation on these platforms also show a direct correlation with the measured mechanical properties; hence, understanding nanomechanical properties provides insights into designing new antibacterial polymer coatings.
1.Lee, H.-S. et al. Biomacromolecules 2015, 16, 650.
2.Nalam, C. P. et al. ACS Appl. Mater. Interfaces 2017, 9, 12936.
BM11.07: Study and Regulation of Biopolymer-Cell Interactions
Tuesday AM, November 28, 2017
Sheraton, 2nd Floor, Liberty BC
10:30 AM - *BM11.07.01
Bioinspired Polymers for the Regulation of Microbial Virulence
Katharina Ribbeck 1 Show Abstract
1 , MIT, Cambridge, Massachusetts, United States
Mucus is a biological gel that lines all wet epithelia in the body, including the mouth, lungs, and digestive tracts, and has evolved to protect us from pathogenic invasion. Microbial pathogenesis in these mucosal systems, however, is often studied in mucus- free environments, which lack the geometric constraints and microbial interactions that are found in natural, three- dimensional mucus gels. To bridge this gap, my laboratory has developed model test systems based on purified mucin polymers, the major gel-forming constituents of the mucus barrier. We use this model to understand how the mucus barrier influences bacterial virulence, and moreover, to elucidate strategies used by microbes to overcome the normal protective mucus barrier. I will discuss data showing that the mucus environment has a significant impact on the physiological behavior of microbes, including surface attachment, quorum sensing, the expression of virulence genes, and biofilm formation. The picture is emerging that mucins are key host players in the regulation of microbial virulence and can guide the fabrication of advanced polymers to regulate host-microbe interactions.
11:00 AM - BM11.07.02
A Carbohydrate-Based Elastomer with Tunable Properties for Biomedical Applications
Haoran Liu 1 , Xiao Lin 1 , Huilin Yang 1 2 , Lei Yang 1 2 Show Abstract
1 Institute of Orthopaedics and Department of Orthopaedics, Soochow University, Suzhou, Jiangsu, China, 2 , International Research Center for Translational Orthopaedics (IRCTO), Suzhou, Jiangsu, China
Biopolymer-derived materials have attracted lots of attention in biomedical engineering and healthcare technology due to their superior biocompatibility, bioactivity or similarity to biological systems. Here we report a starch-derived elastomer modified by adding PDMS which possesses tunable properties to meet the different requirements of biomedical applications. The carbohydrate-based elastomer (CBE) is injectable, biocompatible, anti-infective and, more importantly, has a series of tunable properties including stretchability (up to 300%), humidity sensitivity, compressive strength (0.35~1.5MPa) and conductivity (0.01~1.5 mS/cm). We also reported three examples of the optimization of the CBE properties for different biomedical applications. In the first example, CBE was engineered to achieve a high sensitivity to humidity with a wide detection range, making it into a flexible and portable humidity sensor for potential monitoring breathing rates or breath arrest. In the second example, CBE was tailored to have high flexibility and conductivity, enabling a fabrication of electronic skin that responses to external mechanical stimuli such as stress and strain. Such CBE also has potential to be used in flexible circuits and wearable electronics. In the last example, CBE is designed to treat refractory wounds featured by the lack of blood supply and vascularization, repeated infection and fibrous tissue hyperplasia. The CBE is modified to become highly biocompatible with fibroblast and endothelial cells while efficiently inhibitory against E.coli and S.aurues. These properties render CBE a promising wound dressing materials for the accelerated wound healing and tissue repair.
11:15 AM - BM11.07.03
Bioresponsive Prophylaxis Effectively Ameliorates Acute Inflammatory Flare-Ups
Alexandra Stubelius 1 , Wangzhong Sheng 1 , Jason Olejniczak 1 , Sangeun Lee 1 , Monica Guma 1 , Adah Almutairi 1 Show Abstract
1 , UC San Diego, La Jolla, California, United States
Bioresponsive particles have been developed with the aim to increase drug delivery precision. Here, we utilize a disease-triggered, on-demand drug delivery option to improve prophylaxis for acute inflammatory flares. Preventing an inflammatory flare before or close to its onset would limit cell infiltration and long-term tissue destruction in diseases such as gout. Inflammation responsive, pH-sensitive, acetalated dextran (AcDex) particles were engineered by electrospray and loaded with dexamethasone (DXM). In a six-day in vitro prophylaxis assay, macrophages were pre-treated with free DXM, AcDex-DXM particles, or control slow-release poly(lactic-co-glycolic acid; PLGA)-DXM particles before stimulation with LPS and monosodium urate crystals (MSU) to initiate inflammation. AcDex-DXM was the only pre-treatment that reduced IL-1β. In vivo, the prophylaxis efficacy was assessed by pre-treating either animals undergoing the murine air pouch model 24-hours before MSU crystal injections, or by pre-treating murine joints eight days prior to MSU injections. In both models, only AcDex-DXM significantly reduced cell infiltration and IL-1β and CXCL1. In conclusion, we have successfully demonstrated the superior efficacy offered by bioresponsive drug delivery over traditional free drug and drug-encapsulation as prophylaxis to achieve adequate anti-inflammatory effects for acute flares. To the best of our knowledge, this approach and results are pioneering, promising exciting treatment opportunities for multiple inflammatory conditions.
11:30 AM - *BM11.07.04
Adaptable Biomaterials to Maintain Stemness of Neural Progenitor Cells
Christopher Madl 1 , Sarah Heilshorn 1 Show Abstract
1 , Stanford University, Stanford, California, United States
While neural progenitor cells (NPCs) and their progeny have significant therapeutic promise, the difficulty and cost of expanding a large number of NPCs remains a significant barrier to widespread clinical use. Recently, 3D hydrogels have been proposed as in vitro culture platforms for the expansion of stem cell populations to overcome the space limitations of 2D culture. However, very little is known about which 3D material properties are required to maintain NPCs in an undifferentiated state for expansion. Here we use a family of protein-engineered, elastin-like proteins to systematically evaluate the material requirements for NPC expansion. It is well-established that matrix stiffness modulates stemness in strongly adherent stem cells, including mesenchymal stem cells and muscle satellite cells, but the impact of stiffness on stemness maintenance in less contractile stem cells such as NPCs is not well known. We present data demonstrating that 3D matrix stiffness does not correlate with the maintenance of NPC stemness over a broad range of matrix mechanical properties (E~0.5-50 kPa). In contrast, matrix degradability strongly correlated with the expression of NPC stem markers and NPC proliferation in two different biomaterial systems. Our results have identified matrix remodeling as a previously unknown requirement for maintenance of NPC stemness in 3D hydrogels and suggest that adaptable biomaterials will be useful for expansion of therapeutically relevant numbers of NPCs.
BM11.08: Structural Biopolymers for Sustained Drug Release
Tuesday PM, November 28, 2017
Sheraton, 2nd Floor, Liberty BC
1:30 PM - *BM11.08.01
Three-Dimensional Microphase Separation Leads to Synergistic Permeability in Lipid-Polymer Hybrid Constructs
Cecilia Leal 1 Show Abstract
1 , University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
Lipids and polymers are heavily and successfully utilized as drug delivery systems. This is traditionally done in the form of suspended nanoparticles. Drug delivery coatings is an emerging technology that enables spatial control and localized delivery. However, reports on the use of substrate-mediated lipid and polymer drug delivery systems are scarce and have suffered from low efficiency. Existing studies have focused on optimizing release by degradation or swelling of an unstructured polymer film. In this presentation we thoroughly investigate a new class of hybrid lipid-polymer multilayered system with nanostructures that enable synergistic and controlled delivery of paclitaxel – a powerful drug that is often challenging to encapsulate and release.
While lipid-polymer hybrids have been studied in the form of vesicles or supported bilayers, we developed a methodology to adsorb hybrid multilayers onto a solid substrate. We employ Grazing Incidence Small Angle X-ray Scattering, Atomic Force Microscopy, Solid-State Nuclear Magnetic Resonance, and Confocal Microscopy to demonstrate that the membranes exhibit remarkable ordering, peculiar phase behavior, and dynamical properties. Specifically, lipids and polymers partition into polymer-rich and lipid-rich domains that are in complete registry across micrometer-thick films. This yields an unprecedented hybrid membrane system exhibiting three-dimensional microphase separation. These nanostructures impose translational diffusivity behavior of paclitaxel deviating from what is generally observed in conventional membranes. This results in a drug release profile that is dramatically enhanced compared to pure polymer or lipid films.
2:00 PM - BM11.08.02
Novel Applications of Binary Lipid Nanoparticles—Thermoresponsive Drug Delivery and Drug-Free Treatment of Infections
Mubashar Rehman 1 2 3 , Asadullah Madni 3 , Ayesha Ihsan 2 , Thomas Webster 4 , Nicole Bassous 1 Show Abstract
1 , Northeastern University, Boston, Massachusetts, United States, 2 NanoBiotechnology, NIBGE, Faisalabad, Punjab, Pakistan, 3 Pharmacy, Islamia University of Bahawalpur, Bahawalpur, Punjab, Pakistan, 4 Department of Chemical Engineering, Northeastern University, Boston, Massachusetts, United States
Lipid nanoparticles consisting of solid and liquid lipids have been widely used for bioavailability enhancement and the sustained drug release of water insoluble drugs. The lipid nanoparticles can be made from liquid oils (emulsions), solid lipids (SLN) or their binary mixture (NLC). Recently, we have described that binary lipid nanoparticles can be synthesized with tunable melting by optimizing the amount of oil. Therefore, we optimized these nanoparticles for thermoresponsive drug release at hyperthermic temperature i.e. >39°C. The thermoresponsive lipids, either pure lipid or lipid mixtures, were prepared with different composition to melt at 39°C. Thermoresponsive lipids were made into nanoparticles that would undergo solid-liquid phase transition at 39°C and release the payload. Thermoresponsive lipid nanoparticles (TLN) were found with desirable physicochemical characteristics. The thermoresponsive nature of lipid mixtures and TLN was confirmed by viscosity and light transmission studies at as function of temperature. Dissolution studies were performed by the dialysis bag method and a modified electrochemical method for real time detection thermoresponsive drug release at 37°C to 39°C. We found that drug release slower at 37°C which is characteristic of lipid nanoparticles. However, drug was released abruptly at 39°C. The faster drug release was due to high diffusion rate found in liquid dosage forms. Next, thermoresponsive cytotoxicity of the TLN was evaluated against different cancer cells. Further, TLN showed higher permeability at 39°C across in vitro blood-brain barrier model due to deformability of TLN in liquid state. Next, we have demonstrated antimicrobial activity of TLN synthesized from medium chain fatty acids due to their widely reported antimicrobial properties. TLN found to be effective against both Gram positive and negative bacteria which was similar to standard antibiotics used for treatment of infectious diseases. In summary, the binary TLN prepared by us may find broad range of applications in biomedical field such as targeted drug delivery and as antimicrobial agents.
2:15 PM - *BM11.08.03
Peptide-Containing Conjugates for Triggered Assembly and Controlled Delivery from Biomaterial Scaffolds
Kristi Kiick 1 Show Abstract
1 , University of Delaware, Newark, Delaware, United States
Motifs from structural proteins, such as collagen and resilin, offer important opportunities in designing biomaterials with interesting mechanical and stimuli-responsive behavior. Their conjugation to polymers including poly(ethylene) glycol, poly(ethyleneimine), or thermally responsive poly(acrylate)-based polymers, affords biomaterials with diverse properties responsive to multiple biologically relevant triggers. Conjugates are able to form a range of structures that modulate cell behavior and influence the retention and release of cargo, offering substantial improvement in cargo activity over that achieved by free nanoparticles. These materials can be designed with microstructural heterogeneity as well as into particles that are useful in a variety of drug delivery approaches.
2:45 PM - BM11.08.04
Self-Assembled Gene and Drug Delivery Vectors Based on Natural Polymers and Their Functional Derivatives
Sixue Cheng 1 Show Abstract
1 , Wuhan University, Wuhan China
In gene and drug delivery, nano-sized delivery systems have favorable properties to overcome delivery barriers and to achieve improved therapeutic efficiency. The purpose of our study is to develop a facile strategy to construct multi-functional nano-sized drug delivery vectors with ideal biocompatibility and biodegradability.
A series of gene and drug delivery systems based on natural polymers were prepared by supramolecular self-assembly [1-4]. All functional components, including natural polymers and their derivatives, inorganic compounds (CaCO3 and CaP), nucleic acids and drugs, were introduced to the delivery systems by self-assembly. The typical examples of the delivery systems are as follows.
Mannosylated carboxymethyl chitosan/protamine sulfate/CaCO3/CpG ODN nanoparticles exhibit a significantly enhanced ODN delivery efficiency due to the mannose mediated endocytosis and the favorable effect of protamine sulfate in overcoming delivery barriers. The regulation of NF-κB activity by our ODN delivery system results in dramatically increased production of proinflammatory cytokines including IL-12, IL-6, and TNF-α in RAW264.7 cells and a M1-to-M2 transition of macrophages.
Aptamer incorporated carboxymethyl chitosan/biotinylated carboxymethyl chitosan/protamine sulfate/CaCO3/CaP/plasmid can deliver CRISPR-Cas9 plasmid to targeted tumor cells and realize genome editing effectively. The tumor targeted nanoparticles loaded with CRISPR/Cas9 plasmid targeting CDK11 can inhibit tumor cell growth by CDK11 knockout, and down-regulate the expressions of VEGF, MMP-9 and survivin, implying the favorable effects of the delivery system on inhibition of tumor development and progression.
Biotinylated heparin/heparin/protamine/CaCO3/DOX/TQR nanovesicles for co-delivery of an anti-tumor drug DOX (doxorubicin hydrochloride) and a drug resistance inhibitor TQR (tariquidar) show significantly improved tumor cell inhibitory efficiency for drug resistant cells due to the enhanced intracellular and nuclear drug accumulation through effective inhibition of the P-gp efflux transporter.
Our studies show these delivery systems can effectively load and deliver various nucleic acids and drugs. All functional components to overcome delivery barriers can be introduced to the vectors by self-assembly conveniently. This self-assembly strategy has great potentials in preparation of diverse gene and drug delivery systems.
Acknowledgement: Financial support from National Natural Science Foundation of China (51533006) is gratefully acknowledged.
1. He XY, Liu BY, Ai SL, Xu L, Zhuo RX, Cheng SX, Mater. Today Chem. 2017, 4, 106-116.
2. Wu JL, He XY, Liu BY, Gong MQ, Zhuo RX, Cheng SX, J. Mater. Chem. B 2017, DOI: 10.1039/c7tb00655a.
3. Gong MQ, Wu C, He XY, Zong JY, Wu JL, Zhuo RX, Cheng SX, Pharm. Res. 2017, 34, 148-160.
4. Gong MQ, Wu JL, Chen B, Zhuo RX, Cheng SX, Langmuir 2015, 31, 5115-5122.
BM11.09: Structural Biopolymer Networks—Assembly and Hierarchical Organization
Tuesday PM, November 28, 2017
Sheraton, 2nd Floor, Liberty BC
3:30 PM - *BM11.09.01
From Collagen Self-Assembly to Biomimetics Materials for Tissue Engineering and Biomineralization Studies
Nadine Nassif 1 Show Abstract
1 , LCMCP (CNRS-UPMC-College de France) et ESPCI, Paris France
Sorbonne Universités UPMC Univ Paris 06, CNRS, Collège de France, Laboratoire Chimie de la Matière Condensée de Paris, 4 place Jussieu, 75005 Paris, France
ESPCI Paris, PSL Research University, CNRS, Institut Langevin, 1 rue Jussieu, 75005 Paris, France
In biological tissues, a common feature is the presence of dense arrays of biopolymers with ordered geometries at the ultrastructural level. A relationship has been established between two scientific fields, namely cellular biology and physico-chemistry, by showing the similarity of such three-dimensional arrangements formed by the biological polymers and molecules in liquid crystals (see publications of Yves Bouligand). This structural analogy between living tissues and liquid crystals was suggesting similar self-assembly mechanisms in both systems. For Type I collagen (the major structural protein of connective tissue), the liquid crystalline self-assemblies was shown forming cholesteric phases in highly concentrated collagen solutions at the molecular level. After a sol/gel transition, collagen fibrils are formed while preserving the cholesteric geometry (see publications of Marie-Madeleine Giraud-Guille).
Recently, the samples were scaled up (from drop to bulk material) using a process based on a continuous injection of collagen in order to increase its concentration (i.e. accretion). Phase transitions being function of the concentration, a variety of liquid crystalline textures forms. The corresponding dense fibrillar collagen matrices at variable concentrations offer routes to produce a range of simple, non-toxic materials. Moreover, coupling the liquid-crystalline properties of collagen to a hydroxyapatite mineralization process, leads to the synthesis of a collagen/apatite composite with high similarities with the bone tissue in terms of composition and structure.
We will show that the resulting materials provide original models to study fundamental questions on tissue morphogenesis and more particularly, bone biomineralization. In vitro and in vivo investigations were performed to control their cyto- and biocompatibility and to evaluate their potentialities as bone repair. They are found to be a good starting point for applications in bone tissue engineering through the design of new implantable materials since autologous bone is still considered as the gold standard.
4:00 PM - BM11.09.02
Mechanics of a Unique Biopolymer Network—Fungal Mycelium
Mohammad Islam 1 , Greg Tudryn 2 , Ronald Bucinell 3 , Catalin Picu 1 , Linda Schadler 1 Show Abstract
1 , Rensselaer Polytechnic Institute, Troy, New York, United States, 2 , Ecovative Design LLC, Green Island, New York, United States, 3 , Union College, Schenectady, New York, United States
Fungal mycelium, the root structure of fungi, is a biopolymer network that has the potential to be the alternative of synthetic plastics. In addition, mycelium when combined with other agricultural waste particles forms a completely biodegradable composite material. In this work, we have studied the morphological and mechanical properties of mycelium to reveal important structure-property relationships of this unique biomaterial. Our experimental results reveal that mycelium exhibits significant non-linear stress-strain behavior both under tension and compression. Significantly, we observe that mycelium exhibits considerable strain hardening before rupture under tension and it mimics open cell foam behavior under compression with strain dependent hysteresis and stress softening behavior under cyclic loading condition. Based on our morphological characterization and experimental observations, we have developed a topologically equivalent random fiber network model which provides further insight into the microstructural origin of mycelium’s mechanical response. Moving up to the scale of the bio-composite, we performed mechanical tests and used the results to validate a continuum-level model of the composite. Further, the multiscale model has been used to perform a parametric study in order to identify the key structural parameters that can be used to control the macroscale material performance.
4:15 PM - BM11.09.03
Role of Cohesion in the Mechanics of Biopolymer Networks
Ahmed Sengab 1 , Vineet Negi 1 , Catalin Picu 1 Show Abstract
1 Mechanical Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York, United States
Many biological materials have as their primary structural element a random network or elastin and/or collagen filaments. The mechanical behavior of the tissue is controlled to a large extent by the mechanics of the network. This can be described in terms of a number of structural parameters, such as the network density, degree of cross-linking and preferential filament orientation, and in terms of the mechanical properties of the fibers (bending and axial stiffness, non-linear behavior, etc). Since individual filaments have sub-micron diameters, cohesion plays an important role leading to the formation of bundles. In this work we explore the role of cohesion on the mechanical behavior of the network. We consider both networks in which the filaments are cross-linked and networks in which filaments are not cross-linked and are free to re-organize in super-structures. We first investigate the stability of such structures and then analyze the role of cohesion in network deformation, in particular the effect on the modulus and non-linear deformation under uniaxial loading.
4:30 PM - BM11.09.04
Nanoporous Biological Hierarchical Composites Inspired from Wood, from Atomistic to Continuum Modeling of Swelling
Dominique Derome 1 , Jan Carmeliet 2 Show Abstract
1 , Empa, Duebendorf Switzerland, 2 , ETH Zürich, Zurich Switzerland
The interaction of many biopolymers, such as cellulose or lignin, with water is known to rearrange their internal structure, make them moisture sensitive and influence their physical properties. One such composite polymeric material is the layer S2 of wood cell walls. We study the different components, a cellulose microfibril and a microfibril aggregate, in terms of the coupled effects of water sorption on hygric and mechanical properties. Modeling at molecular scale using Molecular Dynamics (MD) is used to characterize the hygromechanical behavior at nanoscale of polymeric systems inspired by the biological composite that is wood.
The work aims at elucidating the origin of the hygro-mechanical behavior of such complex polymeric materials.
Using MD simulations, we constructed and investigated a three-phase model of a cellulose microfibril aggregate that consists of crystalline cellulose, amorphous hemicellulose and lignin. The model is studied with MD simulations, where the explicitly present atoms are moved based on the integration of the Newton equation of motion. MD results are upscaled and used in continuum models, using a poromechanical framework thus with full coupling of fluid transport and mechanical behavior. Upscaling to cellular scale is delineated, where the cellular scale is informed through accurate geometrical description using X-ray CT at different relative humidity. The ensemble of results documents the full co-occurrence of sorption and swelling.
We use wood as a model hygroscopic material. As water molecules are adsorbed into the hydrophilic matrix in the cell walls, the induced fluid-solid interaction forces result in a swelling of the cell walls. Moisture-induced internal stresses highly influence the hygro-mechanical behavior of wood as observed at the macroscale. Adsorption of moisture in wood, in the hygroscopic range i.e. until around 30% moisture content mass per mass, results in swelling up to 10% volumetrically and reduces the stiffness up to two orders of magnitude depending on the crystalline phase direction.
Modeling provides the capability to determine material properties and behavior which cannot be directly determined from experiments and to explore new pathways for material development and technology innovation, especially for capacity in terms of moisture-induced deformation and shape memory behavior.
We acknowledge the contributions of PhD students Chi Zhang, Mingyang Chen and Dr. Karol Kulasinski as insights for this abstract.
4:45 PM - BM11.09.05
Fracture of (bio)polymers with Diffusive Species
Yunwei Mao 1 , Lallit Anand 1 Show Abstract
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
An (bio)polymeric gel/material is a cross-linked polymer network swollen with a solvent (fluid). The material eventually ruptures as the concentration of solvents or the deformation change dramatically. Though the various coupled aspects of fluid permeation and large deformations are understood and formulated well, the study on the fracture coupling with large deformation and diffusion of soft materials, especially for biopolymers, is still not fully satisfied. Here we formulates a theory for fracture of polymers with large deformation and diffusive species. The free energy of the undamaged gel results from three molecular processes: entropic stretching the network, mixing the network with the small molecules, and the energetic stretch of the molecular bond of the polymer chains. The fracture process of the gel is captured by extending the phase-field method, which is widely used to describe the damage and fracture of brittle materials. The chain of polymers start to damage as the stored internal energy due to stretch of bonds within polymer chains attain a certain value. Many interesting phenomena coupling with diffusion, deformation, and damage in soft materials then be explored, including (i) swelling and deswelling induced fracture; (ii)delayed fracture; and (iii) rate-dependent toughness due to diffusion.
Benedetto Marelli, Massachusetts Institute of Technology
Fiorenzo Omenetto, Tufts University
Jelena Rnjak-Kovacina, University of New South Wales
Hu Tao, The University of Texas at Austin
Shanghai Runshuo Medical Instrument Co., Ltd.
BM11.10/BM12.06: Joint Session: DNA Materials
Wednesday AM, November 29, 2017
Sheraton, 2nd Floor, Constitution A
8:30 AM - BM11.10.01/BM12.06.01
DNA-Programmed Epitaxy and Heteroepitaxy of Nanoparticle Superlattices
Robert Macfarlane 1 Show Abstract
1 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
The programmability of DNA makes it an attractive structure-directing ligand for the assembly of nanoparticle superlattices with unique structure-dependent physical phenomena. By pairing this “bottom-up” assembly method with “top-down” lithographic techniques and assembling nanoparticle superlattices on a patterned substrate, complete control over crystal size, shape, orientation and unit cell structure can be realized, thereby enabling a new fabrication methodology for manipulating material properties by design. The key challenges in developing this technique are to first understand how different design factors affect the assembly process, and subsequently develop structure-property relationships that correlate the above mentioned design parameters with the resulting overall material structure. Here, a comprehensive approach is taken to study the fundamental components of DNA-programmed superlattice epitaxial growth from a patterned substrate, such as the deposition temperature and the thermodynamics of interfacial energetics, to achieve single-crystal nanoparticle thin films. Using a combination of X-ray diffraction and electron microscopy techniques, both surface morphology and internal thin film structure are examined to provide an understanding of particle attachment and reorganization during growth. Under equilibrium conditions, single crystalline, multilayer thin films can be synthesized over 500 × 500 µm2 areas on lithographically patterned templates, whereas deposition under kinetic conditions leads to the rapid growth of glassy films. Additionally, intentionally mismatching the lithographically defined pattern and nanoparticle superlattice lattice parameters allows for an exploration of the concept of heteroepitaxy in a systemic manner. This novel method for controlling particle assembly draws several strong analogies to traditionally atomic epitaxy/heteroepitaxy, providing a useful tool for understanding thin film growth processes. As a result, we are able to realize 3D architectures of arbitrary domain geometry and size, thereby making materials with unprecedented precision across multiple length scales.
8:45 AM - BM11.10.02/BM12.06.02
Self-Assembly of Heterogeneously Shaped Nanoparticles into Plasmonic Metamolecules on DNA Origami
Risheng Wang 1 , Wenyan Liu 2 , Ling Li 3 , Shuo Yang 1 , Jie Gao 3 Show Abstract
1 Chemistry, Missouri University of Science and Technology, Rolla, Missouri, United States, 2 Center for Research in Energy and Environment, Missouri University of Science and Technology, Rolla, Missouri, United States, 3 Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, Missouri, United States
Plasmonic metamolecules (PMs), typically constructed from multiple metal nanoparticles, have recently attracted tremendous interests due to their abilities to efficiently control and manipulate light in deep subwavelength scale1. The unique optical properties of PMs are strongly dependent on their morphological parameters, such as particle size, shape, and composition, as well as interparticle distance. Thus, in recent years, to realize highly designable and tunable optical properties, considerable efforts have been devoted to engineering various forms of PMs with increasing complexity2-4. Among them, the rational assembly of heterogeneously shaped metal nanoparticles (NPs) into well-defined hetero-PMs holds great promise because they often exhibit novel optical and magnetic coupling modes that cannot obtained from homogeneous systems, such as plasmonic Fano resonance, symmetry breaking, and spectral splitting.
DNA origami5 (a bottom-up self-assembly strategy) has been widely used as scaffold to spatially posit functional nanoparticles with nanometer precision. Herein, we demonstrate the first realization of a complex gold nanorods (AuNR)-gold nanoparticle (AuNP) hetero-heptamer PM and a series of its derivatives. These novel assemblies were fabricated by deliberately organizing AuNRs and AuNPs on a rigid 3D triangular DNA origami frame where its edges serve as AuNR binding sites and its vertexes and central cavity act as AuNP binding sites. We also show that the optical properties of PMs constructed in this manner, which were characterized in the visible range, can be efficiently tuned by selectively regulating the position of each component. The computational simulation of the tailored optical spectra is consistent with the experimental results. We envision that PMs containing hetero-shaped nanoparticles not only provide opportunities for fundamental studies of various of NP-NP interactions, but also for advanced applications in nanotechnology fields.
1. A. Boltasseva, and H. A. Atwater, Science, 2011, 331, 290-291
2. S. Pal, Z. Deng, H. Wang, S. Zou, Y. Liu and H. Yan, JACS, 2011, 133, 17606-17609
3. M. J. Urban, P. K. Dutta, P. Wang, X. Duan, X. Shen, B. Ding , Y. Ke and N. Liu, JACS, 2016, 138, 5495-5498.
4. P. Zhan, P. K. Dutta, P. Wang, G. Song, M. Dai, S. Zhao, Z. Wang, P. Yin, W. Zhang, B. Ding, and Y. Ke, acsNANO, 2017, 11, 1172-1179
5. P. W. K. Rothemund, Nature, 2006, 440, 297-302
9:00 AM - *BM11.10.03/BM12.06.03
Colloidal Crystal Engineering with DNA
Chad Mirkin 1 , Jarad A. Mason 2 Show Abstract
1 , Northwestern University, Evanston, Illinois, United States, 2 Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts, United States
An ideal strategy for materials design would allow one to systematically tune the strength, specificity, and symmetry of interactions between material building blocks without altering the intrinsic properties of the building blocks. Although this level of control is exceedingly difficult to achieve in molecular systems where bonding between atoms is inherently linked to their underlying electronic structure, interactions between nanoparticle components can be dictated, independent of nanoparticle composition, through the attachment of highly programmable surface ligands. The Mirkin group has shown that biomolecules such as DNA can act as programmable ligands for directly encoding material structure. In this sense, DNA-nanoparticle constructs behave as programmable atom equivalents (PAE), where nucleic acids function as programmable “bonds” between nanoparticle “atoms,” analogous to a nanoscale genetic code for material assembly. The sequence and length tunability of nucleic acid bonds has allowed us to define a powerful set of design rules for the construction of nanoparticle superlattices with more than 30 unique lattice symmetries, over one order of magnitude of interparticle distances, and several well-defined crystal habits. This control has enabled exploration of sophisticated symmetry-broken architectures, including a body-centered tetragonal lattice and the most structurally complex colloidal crystal synthesized to date. The nucleic acid bond can also be programmed to respond to external biomolecular and chemical stimuli, allowing structure and properties to be tailored on demand. Notably, this unique genetic approach to materials design affords functional nanoparticle architectures that can be used to catalyze chemical reactions, manipulate light-matter interactions, and improve our fundamental understanding of crystallization processes.
9:30 AM - BM11.10.04/BM12.06.04
Simulation Study of DNA-Guided Colloidal Clathrate Crystals
Sangmin Lee 1 , Michael Engel 2 , Matthew Spellings 1 , Sharon Glotzer 1 3 Show Abstract
1 Chemical Engineering, University of Michigan–Ann Arbor, Ann Arbor, Michigan, United States, 2 Chemical and Biological Engineering, University of Erlangen-Nuremberg, Erlangen Germany, 3 Materials Science and Engineering, University of Michigan–Ann Arbor, Ann Arbor, Michigan, United States
In a recent paper [Lin et al., Science 2017, Vol. 355, pp. 931-935 ], it is reported that clathrate colloidal crystals are experimentally obtainable via DNA functionalization on triangular bipyramid (TBP) gold nanoparticles. Here, we present the simulation study and structural analysis from that paper of the DNA-mediated colloidal clathrates via discrete element molecular dynamics method demonstrating their self-assembly. We show how the shape of the TBPs with 109.5 degree equatorial angle is an optimized geometry to form a tetrahedral network -- a common property of clathrate formers -- by the complementary contact model [Mirkin et al., Science 2011, Vol 334, pp. 204-208], which maximizes face-to-face contacts and DNA hybridization. To simulate TBP assembly into colloidal clathrates, we developed a minimal model for the DNA shell in which the two different parts of the experimentally used DNA are considered separately: i) Double-strand DNA (ds-DNA) which is rigid and non-attractive. ii) Single-strand DNA (ss-DNA) possessing flexibility and attractive force. For the inner ds-DNA shell, a purely repulsive Weeks-Chandler-Anderson (WCA) pair potential is applied between particle cores, and a double-Gaussian model (DGM) is applied to patches on the core to mimic the attractive outer ss-DNA shell. The models are then parameterized using the experimental values. The simple DNA model successfully reproduces experimental observations, forming mixed clathrates (Type II and IV) in 68.7nm DNA and 250nm edge TBP system. With longer DNA (103.2nm) on the same TBP, our simulations predict a clathrate type-II colloidal crystal should be observed. We also construct ideal TBP clathrate structures for each type and characterize the structural features of the experimental crystals.
9:45 AM - BM11.10.05/BM12.06.05
Microrheology in Self-Assembled DNA Hydrogels
Zhongyang Xing 1 , Mykolas Zupkauskas 1 , Tianyang Cao 2 , Dongsheng Liu 2 , Iliya Stove 1 , Robin Lamboll 1 , Erika Eiser 1 Show Abstract
1 Cavendish Laboratory, Cambridge University, Cambridge United Kingdom, 2 Chemistry Department, Tsinghua University, Beijing China
Synthetic DNA has been tailored and widely used as smart building blocks in material science and nanotechnology, owing to its highly specific binding properties and predominate forming behaviour. In recent years, hydrogels purely made of sophisticatedly designed DNA strands or DNA-tethered polymers have generated wide interest in interdisciplinary fields of physics, chemistry and bio-engineering. However, current research mainly focuses on bulk-scaled fabrication and characterization of DNA hydrogels; the fundamental physics of the forming and melting mechanism of this material at short time scale (micro-seconds) still lacks understanding. In our work, we apply Diffusing Wave Spectroscopy (DWS) as a microrheology tool to investigate the rheological behaviour of a simple model of DNA hydrogels over a wide range of frequencies (up to 1 MHz) and temperatures (fully covering melting transition). Results show a clear liquid-to-gel transition as the temperature ranges from above to below the melting temperature, and the typical relaxation times, in the Intensity-Correlation Function (ICF) increase. More interestingly, around the transition temperature, the material itself shows a competing G’ and G’’ relation across a range of frequencies, which indicates a thermally reversible formation of a percolating network of double-stranded DNA and its melting into DNA-clusters phase above the melting temperature. The approach demonstrated here can be easily extended to more complicated DNA-hydrogel systems and provide guidance for the future design of such hydrogels that can be adapted to the application of molecular sensing. On the long term, these hydrogels can be used in extensive areas such as drug delivery, tissue engineering and bio-sensing.
10:30 AM - *BM11.10.06/BM12.06.06
Programming Mechanical Function via DNA Self-Assembly
Carlos Castro 1 Show Abstract
1 , The Ohio State University, Columbus, Ohio, United States
The ability to program folding of DNA into specific target structures via sequence design has enabled the development of DNA nanostructures for applications such as templating of biomolecules or nanoparticles, biophysical measurements, and drug delivery. In addition to forming specific nanoscale geometries, integrating DNA components with varying stiffness including single-stranded DNA, double-stranded DNA, and bundles of double-stranded DNA, allows design of dynamic function. In particular, we have established a design method that relies on incorporating flexible single-stranded connections with stiff component comprising bundles of double-stranded DNA to allow for motion in specific degrees of freedom. We demonstrated this approach by developing DNA joints and mechanisms with programmed 1D, 2D, and 3D motion. These dynamic devices can be reconfigured through binding and competitive displacement of additional DNA strands. While these efforts have taken key steps towards nanomachines, the ability to coordinate motion and conformational changes across many DNA nanostructures remains a critical challenge to enable DNA-based nanorobots and responsive materials.
Our current work seeks to scale the dynamic function of DNA nanomachines by developing assemblies with cooperative, coordinated, and communicating conformational changes. We recently developed a framework for dynamic assemblies inspired by a paper origami design motif termed the waterbomb base. The waterbomb base can be organized into arrays where conformational changes of individual units coordinate to achieve shape changes, such as a flat ribbon to a tube, or a tube to a sphere. We are also developing assemblies to propagate information along an array by a cascade of conformational changes. In these assemblies, a locally triggered conformational change can be passed along an array in a chain reaction where each structure triggers the next one. We characterized the structure of these nanomaterials using transmission electron microscopy and their dynamic behavior using fluorescence-based methods to monitor conformational changes. We anticipate these coordinating and communicating DNA materials can serve as a foundation for materials that sense and respond to their local environment and communicate information throughout the material.
11:00 AM - BM11.10.07/BM12.06.07
Peptide Directed Synthesis of Continuous DNA Nanowires for Analysis of Large DNA Molecules
Kyung-il Kim 1 , Seonghyun Lee 2 , Xuelin Jin 2 , Su Ji Kim 3 , Kyubong Jo 2 , Jungheon Lee 1 3 Show Abstract
1 School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon Korea (the Republic of), 2 Department of Chemistry and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul Korea (the Republic of), 3 , Sungkyunkwan University Advanced Institute of NanoTechnology, Suwon Korea (the Republic of)
Being an important genetic molecule with programmable functionality, DNA is actively studied in diverse areas in cutting-edge science and technology. Although numerous studies have reported the visualization of DNA molecules, most studies were carried out with transmission electron microscopes, atomic force microscopes, or fluorescence microscopes, which are actually not desirable for whole analysis of micro/millimeter sized DNA molecules with nanometer sized features. Although scanning electron microscope (SEM) has great potential for DNA analysis with nanometer scale resolution and millimeter scale permissible range, it has been rarely used to analyze DNA molecules.
In this presentation, we report a novel approach to synthesize smooth and continuous DNA nanowires applicable for analysis of large DNA molecules by SEM. By introducing thiol-tagged DNA binding peptides, we could densely introduce thiol groups into native DNA molecules. This allowed us to immobilize DNA molecules on conductive gold substrates and densely anchor gold nanoparticles onto DNA backbone. Subsequently, we could use these gold nanoparticles as seeds to guide smooth and continuous DNA templated metallization. Using our method, we not only could image smooth and uniform structures of long DNA (λ-DNA, 48.5 kb), its dimer (97 kb), and trimer (145.5 kb), but also observe entangled 3 dimensional images of DNA using SEM, which are very difficult to be achieved with other analytical techniques.
To our knowledge, this work is the first work to report the metallization of smooth and continuous DNA nanowires and demonstrate its application on whole DNA imaging by SEM. Considering the significance of DNA analysis and the power of SEM for high resolution imaging of large scale features, we believe this work can lead new biophysical and biochemical studies on DNA within nano- to millimeter scale levels.
 Kyung-Il Kim et al., Small, 2017, 13 (2), 1601926
11:15 AM - BM11.10.08/BM12.06.08
Nanoparticles for Compaction and Wrapping of DNA and RNA—Strategies for Rational Design
Matthew Manning 1 , Jessica Nash 1 , Yaroslava Yingling 1 Show Abstract
1 , North Carolina State University, Raleigh, North Carolina, United States
Condensation, bending, and wrapping of nucleic acids is of significant biological and clinical importance. DNA wrapping histone proteins control gene expression via transcription factor accessibility. Nucleic acid therapeutics, such as RNA vaccines and gene therapy, show great promise in treating and preventing a variety of diseases, from Ebola to melanoma. Current delivery method rely on viral particles, which can elicit undesirable immune responses and must be manufactured by cell culture. Cationic nanoparticles offer a level of programmability and immuno-compatibility not available with viral vectors. Using atomistic molecular dynamics, we have designed cation-functionalized gold nanoparticles which act as histone mimics to form synthetic nucleosomes or facilitate the packaging of DNA and RNA by wrapping. From this, we have determined the design factors controlling nucleic acid compaction and characterized the associated forces and structural changes.
While DNA is easily precipitated by electrostatic screening and inter-strand attraction with polycations, tight wrapping requires a nanostructure, such as the histone octamer. Nanoparticles of similar charge and shape as the histone assembly are shown to induce the same superhelical turns. We have found nanoparticle charge and solvent ionic strength as key factors to induce wrapping and preserve helical integrity and present a model for investigating the effects of sequence and structure on dynamical nucleosome behavior.
Duplex RNA (dsRNA) fails to condense in the presence of polyamines, which act as powerful condensation agents in DNA. This has been attributed to dsRNA’s deeply buried phosphate groups. By controlling the flexibility and excess free volume of a nanoparticle’s cationic ligands and their distribution in relation to the helical axis, we show that dsRNA can be bent well below its persistence length and without significant helical distortion. This change results from a periodic bending along the long axis of base-pairs and identifies the favored mode of bending in dsRNA.
11:30 AM - *BM11.10.09/BM12.06.09
Nanoscale Construction and Imaging with DNA
Peng Yin 1 Show Abstract
1 , Harvard University, Boston, Massachusetts, United States
I'll discuss how to use DNA to construct and visualize nanoscale structures. We have invented a general framework to program DNA/RNA strands to self-assemble into structures with user-specified geometry or dynamics. By interfacing these nanostructures with other functional molecules, we have introduced digital programmability into diverse application areas, e.g. fabrication of inorganic nanoparticles with arbitrary prescribed shapes, robust DNA probes with near optimal binding specificity, RNA-based genetically encodable translation regulators with unprecedented dynamic range and orthogonality, and a highly multiplexed optical imaging method. For more details of our work, see http://molecular.systems.
BM11.11: Structural Biopolymers for Energy Harvesting, Storage and Conduction
Wednesday PM, November 29, 2017
Sheraton, 2nd Floor, Liberty BC
1:30 PM - *BM11.11.01
Beyond Health, Therapeutics and Monitoring—When Instability Makes Sense
Geraldine Merle 1 Show Abstract
1 , McGill University, Montreal, Quebec, Canada
A large variety of medical problems are addressed by implantable systems to measure physical parameters or to treat diseases. In the past, functional medical implants were considered as “permanent”, and biocompatible materials were at their paramount in medicine to facilitate the implant integration and minimize the immune responses. Unfortunately, these permanent implanted devices can act as a niche for bacterial colonization, causing immune-mediated pathological tissue reactions. Additionally, when only required for short periods of time, patients have to undergo a secondary surgical procedure to remove the implant, which besides the additional trauma of the patients adds risk of additional complications and cost. Over the past decade, the biomaterials landscape for medical devices has evolved and the bioresorbable polymers have attracted a lot of attention to make the entire medical device compatible with service in the human body while being safely metabolised over time.
Since the first generation hydroxyacid biodegradable sutures, plates and screws, a plethora of advanced biopolymers and devices have been introduced with specific functions, such as drug delivery, aiding organ function, stenting etc. Here, all of the constituent materials naturally resorb via hydrolysis and/or metabolic action, preventing the secondary implant removal surgery. Despite great progress in materials science, and bioengineering, most of these implantable bio-devices require a power source, which ideally should not be an enclosed battery. This can restrict the possibility for miniaturisation and lifetime. Additionally, batteries eventually need to be exchanged or an external battery has the disadvantage that wires breach the skin, which can lead to infection. As the progress of biodegradable electronics advances, biodegradable power sources to operate these medical devices will become more important to create entirely implantable self-powered devices. Engineering powered devices connected to organs or tissue that require therapeutic modulation or monitoring, and then disintegrate once they are no longer useful would not only positively affect the patient quality of life but will reduce as well health care costs.
The concept of biofuel cells that mimic the body’s utilization of glucose and oxygen to generate electrical energy has been proposed in the early 20th century, and has been demonstrated preclinically with considerable success. However like the personal transportation fuel cell, the technology has yet to find implemented application that truly benefits patients. The main reasons for this are cost related and the low efficiency of the devices rendering unfeasibly large implants. However as demands on the healthcare system continue to grow, resources to support it diminish and the populations ages, these drivers for innovation may become sufficient to create the breakthroughs needed to bring what is theoretically feasible into reality for future patients.
2:00 PM - *BM11.11.02
Generating Renewable Fuels from Bio-Nano Architectures
Jennifer Cha 1 , Ke Ma 1 , Jelena Rnjak-Kovacina 1 Show Abstract
1 , University of Colorado Boulder, Boulder, Colorado, United States
With increasing demands for alternative sources of fuel, extensive research has focused on discovering methods to generate renewable energy from earth abundant resources. In recent years, a wide range of inorganic nanostructures with high surface areas and tunable band gaps have been synthesized and used as photocatalysts. To increase their activity, Z-scheme photocatalytic systems have been implemented in which multiple types of photoactive materials simultaneously oxidize water and reduce molecules upon photoillumination. In this talk, I will show some recent efforts from my group in utilizing DNA as a structure-directing agent to spatially organize well-defined photoactive donor and acceptor nanocrystals. In the first part, I will demonstrate that in using DNA as a structure directing agent to assemble TiO2 and Pt decorated CdS nanocrystals caused a singificant improvement in water splitting as opposed to utilizing a single type of particle or simply mixing the particles in solution. Potential limitations in H2 production caused by negatively charged DNA on the Pt@CdS nanoparticles was simply fixed by controlling the amount of DNA per CdS nanorod. In addition, DNA also allowed positioning of a single or series of electron mediators site-specifically in between the two catalysts which further increased H2 production.
In a similar vein, I will also show some of our recent efforts in applying Z-schemes for CO2 reduction to usable fuels. In this work, DNA bases of 10, 20, 30, 40 and 80 base were first used to position the TiO2-CdS nanocrystals with interparticle distances of ~3, ~6, ~9, ~12, and ~24 nm, respectively. As compared to either TiO2 alone, Au@CdS alone, or simple mixtures of the two, the DNA assembled TiO2-Au@CdS showed a significant (2.94-5.28 fold) increase in CO2 photoreduction, as evidenced by the generation of formate, formaldehyde, and methanol. Most importantly, and unexpectedly, we show that with this particular Z-scheme, separating the nanoparticles at 9-10 nm showed the highest yields CO2 conversion. This result was found not only for nanocrystals spaced with linear 30mer dsDNA, but also for 40mer DNA composed of both linear and hairpin DNA. While increasing dsDNA lengths further to 40 and 80 bases (~12 and ~24 nm) decreased CO2 photoreduction, the photocatalytic performance of the TiO2-Au@CdS nanoparticle clusters was still significantly greater than mixtures of unlinked nanoparticles. These results demonstrate that electron transfer from TiO2 to Au@CdS can be achieved over DNA lengths that correspond to distances as large as 24 nm. For comparison, a 5 kDa polyethylene glycol (PEG) spacer, which has a rough end-to-end distance of ~11 nm showed a very low amount of CO2 conversion. These results highlight the unique properties of DNA as a tool to accurately control the position and spatial location of each donor-acceptor nanocrystal as well as facilitate charge conduction.
BM11.12: Frontiers in Structural Biopolymers
Wednesday PM, November 29, 2017
Sheraton, 2nd Floor, Liberty BC
3:30 PM - *BM11.12.01
Naturally Derived Bioplastics from Shrimp Shells and Squid—Processing, Fabrication, and Applications
Marco Rolandi 1 Show Abstract
1 , University of California, Santa Cruz, Santa Cruz, California, United States
From the depths of the Mariana trench to the peaks of the Himalayas, human created plastic pollution has reached every corner of the globe, and it is here to stay given the virtually endless time required for most plastics to biodegrade. On the other hand, plastics have revolutionized modern society with simple and inexpensive manufacturing for a variety of products. Here, I will present our attempts to develop processing and fabrication strategies for naturally derived bioplastics made of chitin. Chitin is the second most abundant polysaccharide after cellulose and chitin is found in shrimp shells, crab shells, squid pens, and the exoskeleton of beetles. Examples of our attemps include microfabricated chitin nanofiber composites with silk and gelatin, water-processable squid beak mimics, and Cruz Foam. Cruz Foam is a shrimp shell derived foam designed to replace polyurethane and polystyrene foams in surfboards.
4:00 PM - BM11.12.02
Polymeric Peptide Pigments with Sequence-Encoded Properties
Ayala Lampel 1 , Scott McPhee 1 3 , Hang-Ah Park 2 , Gary Scott 3 , Sunita Humagain 1 , Doeke Hekstra 4 , Barney Yoo 1 , Pim Frederix 5 , Tai-De Li 1 , Rinat Abzalimov 1 , Steven Greenbaum 1 , Tell Tuttle 3 , Tony Hu 6 , Christopher Bettinger 2 , Rein Ulijn 1 Show Abstract
1 , City University of New York (CUNY), New York, New York, United States, 3 , University of Strathclyde, Glasgow United Kingdom, 2 , Carnegie Mellon University, Pittsburgh, Pennsylvania, United States, 4 , Harvard University, Boston, Massachusetts, United States, 5 , Rijksuniversiteit Groningen, Groningen Netherlands, 6 , New York University, New York, New York, United States
Melanins are a family of heterogeneous polymeric pigments that provide UV protection, structural support, coloration and free radical scavenging. Formed by oxidative oligomerization of catecholic small molecules, the physical properties of these materials are influenced by covalent and non-covalent disorder. We report the use of tyrosine-containing tripeptides as tunable precursors for polymeric pigments. In these structures, phenols are presented in a (supra-)molecular context dictated by the peptide sequence by repositioning amino acids. Oxidative polymerization can be tuned in a sequence dependent manner resulting in peptide sequence-encoded properties such as UV absorbance, morphology, coloration and electrochemical properties over a considerable range. Short peptides have low barriers to application and can be easily scaled, suggesting near-term applications in cosmetics and biomedicine.
4:15 PM - BM11.12.03
Formation of Turmeric-Based Thin Films—Substrate-Independent and Transparent Coating
Do Kyoung Yeon 1 , So Hyun Ki 1 , Jeanne Choi 2 , Woo Kyung Cho 1 Show Abstract
1 , Chungnam National University, Daejeon Korea (the Republic of), 2 , Seoul Global High School, Seoul Korea (the Republic of)
Curry stains on clothes and dishes in daily life inspired us to investigate the potential use of a turmeric powder, major ingredient of curry, as a substrate-independent coating material. After condition optimization, the coating solution was made by boiling and filtering a turmeric slurry, and the coating was performed at pH 3, leading to the formation of ultrathin and transparent films. Various inorganic and polymeric substrates were successfully coated with turmeric-based materials, including gold, TiO2, SiO2, glass, stainless steel, indium tin oxide, nylon, polyethylene, polycarbonate, polypropylene, acryl, and polyethylene terephthalate. The turmeric-based coating was also applied to polytetrafluoroethylene (PTFE, TeflonTM) and cyclic olefin copolymer (COC) that are difficult to coat because of their low surface free energy. After double dip-coating, the water contact angle was changed from 118.2o to 49.1o for PTFE and 91.2o to 44.7o for COC. The water contact angles for the other substrates converged to 35o after coating, confirming the substrate-independent, universal coating capability of turmeric. Through the mechanistic studies, we found that the main contributor of the film formation was polyphenolic curcumin. It was also found that amine compounds were involved to enhance the coating efficiency. Compared to the dopamine-based universal coatings, the turmeric/curcumin-based coating was more effective in an acidic environment (pH 3). We believe that this work suggests a chemical approach of curcumin-based functional coatings with various amines. It could be useful for surface functionalization in various research areas such as chemistry, material science, biology, and bioengineering.
4:30 PM - BM11.12.04
Clumping Criteria of Vertical Nanofibers on Surfaces
Ming Zhou 1 2 Show Abstract
1 , Guangxi University of Science and Technology, Liuzhou China, 2 , Tsinghua University, Beijing China
Nanofibers (nanowires, nanohairs, nanopillars, nanofilaments, etc.) are quasi-one-dimensional nanostructures attracting considerable attention because of their wide potential applications, such as ultraviolet nanolasers, solar cells, micro-electro-mechanical systems, lab-on-a-chip devices, biotechnology, and micro-/nano-sensors. With decreased structure size, surface effects play increasingly important roles [1-8]. One of the general challenges is the undesired clumping of fibers caused by their mechanical flexibility and relatively strong attractive adhesion forces, external vibration disturbances and electrostatic forces [9-10], which can diminish their optical and other properties and may even lead to the failure of nanofiber array systems [11-13]. One commonly observed example is the clumping of carbon nanotubes. The undesired clumping of nanofibers must be avoided or better controlled for nanofiber-based applications.
The clumping behaviors of nanofiber arrays depend on their geometry parameters (such as length, radius and spacing distance), surface energy, and bending rigidity of the nanofibers, which accordingly determine the clumping conditions. Many experiments have shown that nanowires could clump in various ways depending on different contact configurations such as tip-tip, tip-side, and side-side contacts [11, 14], which leads to difficulties in predicting the clumping phenomena. A universal clumping criterion is needed to guide the design and fabrication of nanofibers, which is both fundamentally sound and practical for use. Notably, many functional pillar array surfaces, e.g., gecko-inspired adhesives, need to be fabricated by a general anti-failure criterion [32-33]. In this study, three clumping configurations of nanofibers including tip-tip, tip-side and side-side contact (as illustrated in Figure 1) and their critical clumping criteria are theoretically analyzed via a universal model based on elliptical contact theory and the bending theory of cantilevers. Good agreement was achieved between the theoretical predictions and experimental observations. A design for non-clumping carbon nanotube arrays is also given.
4:45 PM - BM11.12.05
Solid (Bio) Polymer Electrolytes for Light-Emitting Electrochemical Cells
Johannes Zimmermann 1 2 , Nils Juergensen 1 2 , Anthony Morfa 1 2 , Gerardo Hernandez-Sosa 1 2 Show Abstract
1 , Karlsruhe Inst of Technology, Karlsruhe Germany, 2 , InnovationLab, Heidelberg Germany
The advent of biodegradable and biocompatible materials has inspired a wide-range of environmentally or physiologically benign device architectures fabricated from bio-derived materials. Organic light-emitting devices have become a big topic in modern research and are often discussed as a future leading technology because of their light weight, flexibility and solution-processability. Here we refer to a further advantage of this technology, namely the possibility of producing biodegradable/biocompatible devices, which offer new fields of application.
On the first part of this contribution, we will discuss solution-processable solid polymer electrolytes (SPE) based on poly(lactic-co-glycolic acid, polycaprolactone and DNA and their application to light-emitting electrochemical cells (LECs) [1,2]. We characterize the performance of the LECs by luminance-current-voltage characteristics and impedance spectroscopy and correlate it to the film morphology. The devices exhibited luimnances over 1000 cd/m2 and operational lifetimes over 30 hours. On the second part, we present the use of choline-based salts as SPE ionic species and the fabrication of devices on flexible biodegradable substartes.
 N. Jürgensen, J. Zimmermann, A. J. Morfa, G. Hernandez-Sosa
Scientific Reports, 6, 36643 (2016)
 J. Zimmermann, N. Jürgensen, A. J. Morfa, B. Wang, S. Tekoglu, G. Hernandez-Sosa
ACS Sustainable Chem. Eng. 4, 7050 (2016)
 A. J. Morfa, T. Rödlmeier, N. Jürgensen, S. Stolz and G. Hernandez-Sosa
Cellulose, 23, 3809 (2016)
BM11.13: Poster Session II
Wednesday PM, November 29, 2017
Hynes, Level 1, Hall B
8:00 PM - BM11.13.01
Producing Biomass Resin from Hornet Silk and Its Excellent Characteristics
Wataru Shouji 1 , Shinji Hirai 2 , Tsunenori Kameda 3 Show Abstract
1 Graduate School Engineering, Muroran Institute of Technology, Muroran, Hokkaido, Japan, 2 Research Center for Environmentally Friendly Materials Engineering, Muroran Institute of Technology, Muroran, Hokkaido, Japan, 3 , National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
Hornet silk was obtained after refining cocoon filaments spun by yellow hornet’s larvae. It consists of fibroin protein like Mulberry silk or a spider’s thread.
In previous work, silk resin was fabricated by heating silk fibroin powder at 150-170 °C under a pressure of 20-30 MPa. Then, it was clarified that the obtained silk resin possessed a extremely high thermal conductivity of 0.44 W/(m °C), glass transition temperature of 180°C, bending strength of 100 MPa and bending elastic modulus of 4.5 GPa. On the other hand, dielectric constant (loss tangent) was 5.8(0.01) at 300 Hz, 4(0.05) at 20 GHz and 4(0.08) even at 300 GHz, respectively. Therefore, silk resin is a promising candidate as electrical circuit materials, because of its excellent heat resistance, heat conductivity, low dielectric constant and a low loss tangent.
A hornet silk protein mainly takes a coil structure. Therefore, it is considered that its physicochemical and mechanical properties differ from those of Mulberry silk with β-sheets structure. In this study, instead of using a silk fibroin powder, a refined Hornet silk powder (moisture content ratio of 10 wt%) was used as a raw material to produce the resin. The research group investigated the influence of grain size of raw material powder on dielectric characteristics and the moisture content of the resin.
Firstly, the cocoon filament was dissolved in a LiBr aqueous solution. Then, hornet silk powder was prepared by freeze-drying from a desalinated fibroin solution. The powder was pulverized by a mixer , and then pulverized powder was sifted in a particle size by a sieve with predefined size mesh. 0.8 g of prepared hornet silk powder was resinified using a hot press with a steel jig of φ20 mm, detailed procedure was described as following. The jig was heated up to 170°C under a pressure of 30 Mpa; then it was immediately cooled by air. Then it was dried for a predetermined time under decompression at 100°C.
The dielectric constant of hornet silk resin derived from the coarse powder in the grain size range between 76 and 106 µm and with a moisture content ratio of 0.18wt%, was estimated to be 4 ~ 5, and the 0.05 (loss tangent) at in the frequency range between 350 and 5 MHz. These values was relatively small, compared with those of a resin derived from conventional silk.
Though conventional silk with β - sheet structure has hydrophobic, Hornet silk possess hydrophilic properties due to its amino acids. In case of Hornet silk powder, while it was resinified using a hot press, it became semi solid due to the moisture of the powder, which enhanced a molecular mobility. Its hydrophilic nature enables us to fabricate homogeneous hornet silk resin compact, compared with conventional silk.
8:00 PM - BM11.13.02
Molecular Dynamics of Amphiphilic Nanoparticles as Transporters of Hydrophobic Small Molecules
Mukarram Tahir 1 Show Abstract
1 Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
The transport of hydrophobic small molecules such as lipids, fatty acids, and lipophilic drugs is facilitated in biological systems by transport proteins such as serum albumin. These proteins can non-covalently encapsulate such molecules through hydrophobic pockets that are a characteristic part of their secondary structure. Recent experiments have shown that nanoparticles functionalized with a surface monolayer of amphiphilic ligands can similarly encapsulate hydrophobic molecules and deliver them across cellular membranes. Here, we use molecular dynamics simulations to uncover an atomistic-resolution understanding of the mechanisms through which nanoparticles can passively entrap hydrophobic molecules and release them into the apolar interior of lipid membranes. Using a combination of unbiased simulations and free energy analysis, we characterize the propensity and dynamics of small molecule incorporation into a nanoparticle's surface monolayer and characterize the resulting impact on nanoparticle morphology. We also investigate the thermodynamics and kinetics of the pathway through which nanoparticles can ultimately deliver encapsulated small molecules to a lipid membrane target. Our findings overall suggest the possibility of engineering synthetic nanostructures that can function as biomimetic transport proteins and provide a means of solubilizing hydrophobic molecules in the aqueous environment of biological systems.
8:00 PM - BM11.13.03
Preliminary Molecular Dynamics Studies of the Montmorillonite, Amylose, Fatty Acids and Water for Polymer-Clay Nanocomposite Modeling
Felipe Silva 2 1 , Elaine Maia 2 , Maria Araújo Sales 2 , Leonardo Giordano Paterno 2 , Mohamed Ghoul 3 , Latifa Chebil 3 Show Abstract
2 Instituto de Química, Universidade de Brasília, Brasília, Distrito Federal, Brazil, 1 , Universidade Catolica de Brasilia, Brasília Brazil, 3 École Nationale Supérieure d’Agronomie et des Industries Alimentaires, Université de Lorraine, Vandœuvre-lès-Nancy, Lorraine, France
The use of biodegradable polymers attracts much attention in polymer science. Although, biopolymers such as starch, present disadvantages such as poor processability. In order to circumvent those disadvantages, researchers mix those polymers with compounds such as clays. This work presents the first part of a theoretical study of a Polymer-Clay Nanocomposite (PCN) composed by: starch, Pequi and Buriti vegetable oils and montmorillonite (MMT), a phyllosilicate. In the present study, an amilose oligomer, oleic, palmitic and stearic acids in the proportion found in those vegetable oils and water, acting as solvent involved in the experimental medium, were studied, as an simplified model, in order to observe the molecular movement; the bonded and nonbonded intermolecular forces and to their structural and behavioural correlations. The calculations were carried out by Molecular Mechanics and Dynamics methods (MM/MD) with the PCFF force field, in confined cells, under PBC and NVT ensemble, at 363 K and variable dynamic times, using Materials StudioTM software. The systems were built in an increasing degree of complexity, in shape and size. During dynamic trajectories, the amylose chains quickly became coiled and strongly aggregated, attracted the polar heads of the fatty acids, hydrogen bonds were formed, and their hydrophobic tails elongate covering the amylose coil. The new knowledge acquired about those molecular systems, works as a starting point to build more complex models, with the inclusion of the MMT and, if the theoretical work converge with the experimental findings, will encourage further studies in the design of PCNs with biopolymers.
8:00 PM - BM11.13.04
Modifications of Nanocellulose for Applications in Crystallizing Pharmaceuticals
Manali Banerjee 1 , Blair Brettmann 1 Show Abstract
1 , Georgia Institute of Technology, Atlanta, Georgia, United States
Cellulose is a highly abundant natural biopolymer that, being a plant-based material, exhibits renewability and biodegradability. A nanoscale form, prepared by removing much of the amorphous cellulose material and leaving small crystalline particles, also presents with high strength, high stiffness and a large surface containing a high concentration of hydroxyl groups. This enables easy surface modification to display a variety of functional groups allowing significant control over nanocellulose interactions with other molecules. This provides the potential for nanocellulose to bind with drug molecules and act as a release inhibitor, a stabilizer or a site for heterogeneous crystallization of the drug itself. We use nanocellulose functionalization, such as carboxylation and sulfonation, to design composites containing nanocellulose and crystallized pharmaceutical products, with an aim towards using the molecular interactions between nanocellulose and drugs to direct formation of desired polymorphs and crystal sizes, leading to flexibility for rational design of nanocellulose-drug composites. The high surface area of the nanocellulose provides a high concentration of interaction sites and the small size of the nanocellulose excipient particles has interesting performance in promoting assembly and packing of the composite in drug products such as compressed tablets, hydrogels, and dense free standing films.
8:00 PM - BM11.13.05
Fucoidan-Based Nanocarriers Mediate Long-Term Potentiation Decay for Early Therapies on Alzheimer's Disease
Chao-Yi Chu 1 , San-Yuan Chen 1 Show Abstract
1 , National Chiao Tung University, Hsinchu Taiwan
Alzheimer’s disease (AD) is the most common neurodegenerative disease, often characterized by extracellular deposition of misfolded amyloid-β(Aβ) peptide and the intracellular formation of neurofibrillary tangles. Recent studies have found that neuroinflammation come as an important indication of AD pathology. The “primed” microglia trigger the innate immune system to realease the inflammatory mediators, which progress and severe the AD. Therefore, we decide to build a biocompatible drug carrier system, use Tat-GluA23Y as drugs to block long-term depression (LTD) at glutamatergic synapses by disrupting the endocytosis of α- amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors (AMPARs). The drug was packed inside the fucoidan/dextran-iron oxide nanoparticles. Fucoidan is natural, anti-immune and anti-inflammatory, dextran provide the hydrophobic characteristic and the covalent bonding sites, and iron oxide as a contrast agent used for magnetic resonance imaging (MRI). At last, Lactoferrin and Congo red will be modified on it The former is to pass the blood-brain-barrier(BBB) and the latter can specifically detect amyloid plaques. (Lf-Congo Red -Fucoidan/iron oxide-Drug-nanopaticles).
The NPs were prepared by modified covalent bond and emulsion cross-linking method. The DLS results showed that the diameter of NPs was about 100~200nm. XPS and FTIR analysis proved the polymerization of Lactoferrin and Congo red. The polymeric Fucoidan-based NPs were almost spherical in shape, as revealed by scanning electron microscopy (SEM). This system can specifically bind to Aβ, have anti-inflammatory characteristic to prolong the disease and may have chance to restore the lost memory.
8:00 PM - BM11.13.06
An Efficient Fluorescence Polymer Oxygen Sensor Compound, Apply to Detect Oxygen Concentration in Environment and Biomedicine
LanFeng Liang 1 , Gang Li 1 , Yanqing Tian 1 Show Abstract
1 , South University of Science and Technology, Shenzhen China
Oxygen is a very important substance in many aspects of life. Fluorometric analysis got lotx of attention because of its high sensitivity and high temporal. But most of them have the imperfection that the fluorescent intensity of them decline in air with time going by. So we aim to design and synthesize a kind of microsphere sensor with a stable property in air. The microsphere sensors, which consist of a platinum octaethylporphyrin(PtOEP) as oxygen sensor and modified Rhodamine B as a reference sensor, can test the oxygen concentration in multifarious environments. Most of the reported fluorescence microsphere were developed by packaging the oxygen sensor in the surface of microspheres thought physical absorption. In this kind of microsphere sensors, the oxygen sensors may fall down from microsphere easily. Therefore, we attempted to use two-stage polymerization to synthesize the polymer microsphere. In this process, Rhodamine B was modified with styrene firstly. Then, the oxygen sensor(PtOEP) was adsorbed into microspheres. In this way, oxygen sensors can be wrapped into the microspheres, not on the microspherens' surface. The strength of emission peaks of PtOEP increased steadily as oxygen concentration decreases. While Rhodamine B is oxygen-insensitive and its emission peak would not change along with the change of oxygen concentration. We can calculate the oxygen concentration by comparing the fluorescence ratio in real time. Based on the above results, the microsphere sensors can be applied to detect oxygen detection directly or prepared as press-sensitive paint. The microsphere sensors exhibited a low measuring error of less than 3% in air and 5% in deionized water. in our study. Moreover, Repeated experiments showed that the fluorescent intensity still can reach 80% after 6 months if the devices were placed in air. In different pH and temperatures, the values could keep on a stable level. In the end, the study turns to biological field, we have studied the property and cytotoxicity in Escerichia coli(E-coli). E-coli were all cultured in the functional polymer in LB(nutrient solution). Oxygen was consumed continually and used up after one hour, the RFU have a obvious variation and elevated 4 times. The cytotoxicity tests showed that nearly no toxic impacts on cell viability. Therefore, the microsphere have a great potential application in bioinstrumentation. In this work, the microsphere showed an outstanding performance of oxygen concentration tests in different environment, which have a good application potential in environmental sciences and biological monitoring.
 J.S.Song, F.Tronc, A Mitchell. Winnik. Polymer. 2006, 47, 817-825.
8:00 PM - BM11.13.07
Unique Cellular Interactions of Gene Delivery Chitosan Nanoparticles after Hyaluronic Acid Coating
Ibrahim Alradwan 1 , Abdulaziz Almalik 1 , Majed Majrashi 1 , Ali Alhasan 1 , Bashaier Alsaffar 1 Show Abstract
1 , King Abdulaziz City for Science and Technology (KACST), Riyadh Saudi Arabia
Nanoparticles (NPs) play an important role in many fields, especially medicine. Our work shows that modified chitosan (CS) NPs are promising nanocarriers with high gene regulation efficiencies when delivering both pDNA and siRNA. In order to accelerate their translation into clinic, biocompatibility examination of such logically synthesized nanoparticles is necessary. In this study we report the cellular responses of uncoated chitosan NPs (CS NPs) and hyaluronic acid coated chitosan NPs (HA-CS NPs) when introduced to Chinese hamster ovary (CHO-k1) cell line.
CHO-k1 cells were treated with a serial dilution of CS and HA-CS NPs (2.5, 0.25, 0.025, 0.0025, and 0.00025 mg/mL) over 24h and 48h. The MTS showed a decrease in cell viability when treated with 2.5 and 0.25 mg/mL CS NPs, where the LDH enzyme was released the greatest. When exposed to such high concentrations of CS NPs, the mitochondrial membrane potential was compromised in CHO-k1 cells in addition to a significant increase in the caspase-3 activity. Interestingly, SOD enzyme was transiently increased in CHO-k1 cells treated with CS NPs as part of their cellular defensive mechanism to remove generated reactive oxygen species (ROS). However, SOD depletion was observed at high concentrations, which suggests the inability of CHO-k1 cells to tolerate such lethal insult.
Our study finds that the toxicity of CS NPs when utilized at high concentrations can be reduced by stably coating them with hyaluronic acid. Indeed, CHO-k1 cells did not show an observed biological stress when exposed to HA-CS NPs. Also, successful gene deliveries of both pDNA and siRNA were achieved using HA-CS NPs as opposed to naked CS NPs. Our findings are important to pave the way for the utilization of hyaluronic acid coated chitosan nanoparticles in nano-drug delivery, as it demonstrates how slight surface modifications can lead to significant differences in cellular response.
8:00 PM - BM11.13.08
Mucins Trigger Flagella-Dependent Dispersal of Established Pseudomonas aeruginosa Biofilms
Julia Co 1 , Gerardo Cárcamo-Oyarce 1 , Nicole Billings 1 , Kelsey Wheeler 1 , Scott Grindy 1 , Niels Holten-Andersen 1 , Katharina Ribbeck 1 Show Abstract
1 , MIT, Cambridge, Massachusetts, United States
Mucus is a biological gel that lines all wet epithelia in the body, including the mouth, lungs, and digestive tracts, and has evolved to protect the body from pathogenic invasion. However, microbial pathogenesis is often studied in mucus-free environments that lack the geometric constraints and biochemical cues that are found in natural, three-dimensional mucus gels. We used fluid-flow and static test systems based on purified mucin polymers, the major gel-forming constituents of the mucus barrier, to understand how the mucus barrier influences bacterial virulence, particularly the integrity of Pseudomonas aeruginosa biofilms, which can become resistant to immune clearance and antimicrobial agents. We found that mucins separate the cells in P. aeruginosa biofilms and disperse them into suspension. Mucins triggered biofilm disassembly without killing the cells, suggesting a mechanism that limits the selective pressure for resistance. Cellular dispersion depended on cellular motility, indicating a role for functional flagella. Taken together, our observations support a model in which host mucins are key players in the regulation of microbial virulence. Our work may also inspire the development of novel advanced polymers and materials to treat, or prevent, biofilms.
8:00 PM - BM11.13.09
Interdigitated Polyelectrolytes and Polymer Brushes—Weakly Interpenetration Regime
Parth Desai 1 , Shayandev Sinha 1 , Siddhartha Das 1 Show Abstract
1 , University of Maryland, College Park, Maryland, United States
Interdigitated polyelectrolytes (PE) and polymers are closest analogues to polymers present in cartilage tissue and other biological joints. They undergo shear and friction forces during the movements of the joints. Hence investigating interdigitated PE and polymer brushes gives insight into the complex interplay of effects influencing those situations. We employ Molecular Dynamics (MD) simulations and develop new scaling laws to probe the behavior of PE and polymer brushes in the weakly interpenetrating regime. Very little research, to date, has focused on describing the compression in this regime. This regime is characterized by the condition dg being more than d0 but less than 2d0, where dg is the gap between two opposing surfaces with grafted PE or polymer brushes and d0 is the unperturbed brush height. We get contrasting results for the length of interpenetration in PE and polymer brushes, but the compression of the PE and polymer brushes show nearly identical trends. For both PE and polymer bilayers (BBL), we find that the brush height in this regime, instead of being solely dictated by the interpenetration length, can be expressed in a power law form where d scales as Nχ (where N is the polymer size). The exponent χ shows a monotonic increase with a decrease in the degree of interpenetration. For the case of PE bilayers, we get another length scale from the concentration profiles of the counter-ions, this shows a higher concentration of counter-ions near the center. This higher concentration can be used to trigger stronger electro-kinetic flows in BBLs. The ion concentration profile with respect to dg / d0 shows a nontrivial trend. Details of the scaling laws and concentration profiles will be presented.
8:00 PM - BM11.13.10
Continuous Synthesis Process of Polyimide Sponge and Its Pore Size Control
Gunhwi Kim 1 , Jinyoung Kim 1 , Daero Lee 1 , Jinuk Kwon 2 , Haksoo Han 1 Show Abstract
1 , Yonsei University, Seoul Korea (the Republic of), 2 , Hankook Tire, Daejeon Korea (the Republic of)
The newly developed porous polyimide membrane exhibited excellent performance, and it can be applied in various industries such as energy storage industry, bio-technology, and etc. However, it is still hard to be applied in industries to be commercialized because of its complicated synthesizing process which is based on batch system not suitable to producing line in factory. In addition, in order to enlarge its application fields, the pore size controlling method still need to be developed. In this study, we successfully fabricated porous polyimide sponge in continuous system, and controlled its pore size by applying Jurin’s law which is widely used for explaining capillary phenomenon. We used non-solvent induced phase separation technology which can be applied in roll-to-roll process, and we confirmed a tendency that as the height of non-solvent height grows, the smaller pore size of membrane obtained with its porosity maintained. The properties of successfully fabricated product are confirmed by TGA, DSC, FE-SEM to observe its thermal and structural features. Newly fabricated polyimide sponge has a honeycomb-like 3-dimensional porous structure with polyimide’s properties maintained, it will be a great candidate for various industries due to its great performance.
8:00 PM - BM11.13.11
Polydiacetylene(PDA)-Perylenediimde(PDI) Supramolecular Nanofibers
Joonsik Seo 1 2 Show Abstract
1 Department of Chemical Engineering, Hanyang University, Seoul Korea (the Republic of), 2 Institute of Nano Science and Technology, Hanyang University, Seoul Korea (the Republic of)
Polydiacetylenes (PDAs) have been extensively investigated owing to their unique structural and optical properties. Introduction of functional dye molecules into the supramolecular PDA could afford generation of new functional PDAs. Herein, we report stimulus-responsive supramolecular nanofibers derived from perylenediimide (PDI)-containing photopolymerizable diacetylenes (PDI-DAs). Self-assembly of the monomer followed by UV irradiation afforded PDI-containing PDAs. The polymer displayed a reversible thermochromism between 25 oC and 80 oC. Interestingly, fluorescence of PDI in the supramolecular structure was quenched by UV-induced polymerization of the DA moieties presumably via resonance energy transfer from excited state of PDI to the blue-phase PDA. The fluorescence was regenerated by heating the dye-containing polymer. Also DA moieties can be polymerized by heat. Nanofibers derived from perylenediimide (PDI)-containing diacetylene can be polymerized by heat and show great enhancement of conductivity. The strategy developed in this study could be useful in the development of new functional PDAs.