Biological materials naturally display an astonishing variety of sophisticated nanostructures that are difficult to obtain even with the most technologically advanced synthetic methodologies. Inspired from nature materials with hierarchical structures, many functional materials are developed based on the templating synthesis method. This review will introduce the way to fabricate novel functional materials based on nature bio-structures with a great diversity of morphologies, in State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University in near five years. We focused on replicating the morphological characteristics and the functionality of a biological species (e.g. wood, agriculture castoff, butterfly wings). We change their original components into our desired materials with original morphologies faithfully kept. Properties of the obtained materials are studied in details. Based on these results, we discuss the possibility of using these materials in photonic control, solar cells, electromagnetic shielding, energy harvesting, and gas sensitive devices, et al. In addition, the fabrication method could be applied to other nature substrate template and inorganic systems that could eventually lead to the production of optical, magnetic. or electric devices or components as building blocks for nanoelectronic, magnetic, or photonic integrated systems. These bioinspired functional materials with improved performance characteristics are becoming increasing important, which will have great values on the development on structural function materials in the near future.

The National Aeronautics and Space Administration (NASA) is currently evaluating composite materials for primary and secondary structures. Composite materials are of great interest to NASA due to the potential significant mass savings they would bring, resulting in more efficient deep space exploration. A principal concern is that of lack of damage tolerance, where nearly imperceptible cracks can have drastic effects on structural integrity. To compensate, composites structures are currently designed to be thicker and heavier than would otherwise be required, thus negating the weight savings they promise. Self-healing composites could help improve damage tolerance and in addition can reduce the complexity of composite maintenance while increasing materials performance lifetime and improving reliability. Current work at the Johnson Space Center investigates the use of carbon nanotubes in a thermally activated re-polymerizing matrix in order to develop a self-healing composite.
Composite panels consisting of carbon nanotubes, carbon fibers, and a thermally reversible polymer resin were fabricated and tested. These multifunctional composites exhibit improvements in the thermal, electrical, and mechanical properties. Nanotube additions influence thermal properties through a decrease in the glass transition and increases in the heat capacity, thermal expansion coefficient, and thermal conductivity of the composite. The electrical conductivity is drastically lowered, while storage modulus and toughness are increased. Carbon nanotubes are known to exhibit enhanced microwave heating, and this property is exploited for the heat generation required for healing of the matrix. Incorporation of nanotubes results in better heating efficiency and thermal transport, allowing the composite to be uniformly heated to the target temperature for self healing. Furthermore, microwave irradiation of impacted composites demonstrates the ability to provide visual inspection of the damaged area. Microcracks produced by impaction generate localized heating which are clearly evident in the thermal images of microwave irradiated composites. The ability to use microwaves to observe barely visual damage provides the capacity for damage detection and real-time health monitoring of the healing process. Thus, carbon nanotubes embedded in a thermally reversible polymer matrix can result in a multifunctional nanocomposite with healing and health monitoring capability.

The use of biological materials as templates for functional molecular assemblies is an active research field at the interface between chemistry, biology, and materials science. We demonstrate formation of gold nanofiber films on beta-sheet peptide domains assembled at the air/water interface. The gold deposition scheme employed a recently-discovered versatile chemical process involving spontaneous crystallization and reduction of water-soluble gold-thiocyanate complex upon anchoring to surface-displayed amine moieties (Morag et al, Advanced Functional Materials, 2013, DOI: 10.1002/adfm.201300881). We show that an interlinked network of crystalline Au nanofibers is readily formed upon incubation of the Au(III) thiocyanate complex with the peptide monolayers. Intriguingly, the resultant films were optically transparent, enabled electrical conductivity, and displayed pronounced surface enhanced Raman spectroscopy (SERS) activity, making the approach a promising avenue for construction of nano-structured films exhibiting varied practical applications and functionalities.

In this study, biodegradable nanofoams were produced using cellulose nanofibrils (CNFs) and starch (S). The availability of high volumes of CNFs at lower costs is rapidly progressing with advances in pilot-scale and commercial facilities. The composite foams were produced using a freeze-drying process with CNF/S water suspensions ranging from 1 to 7.5 wt. % solids content. Microscopic evaluation showed that the foams have microcellular structure includes foam walls covered with CNF`s. Microscopic evaluation of the nanofibrils and pore sizes at the foam walls showed no difference among the composites (CNF reinforced starch foams), with average values from 20 nm to 100 nm for pore size diameters and 30 nm to 100 nm for fibril diameters. The physical, mechanical and thermal properties of the CNF/S composite foams were determined according to ASTM standards. The resulting CNF/S composite foam were determined to have an open-cell structure with densities ranging from 0.012 to 0.082 g/cm3 with corresponding porosities between 93.46% and 99.10%. Thermal conductivity ranged from 0.041 to 0.054 W/m-K. Changes in the solids content and CNF/S ratio had little impact on thermal conductivity of the foams. The mechanical performance of the foams produced from the unreinforced starch control was extremely low and the material was very friable. The addition of CNF to starch produced foams, which exhibited structural integrity. The 1.5% CNF-6% starch combination showed significantly better mechanical properties (average of 2530 kPa modulus of elasticity, 6590 kPa modulus of rupture, 907 kPa compression modulus and 3330 kPa compressive strength) when compared with the other composite formulations. The mechanical properties of materials increased with an increase in solids content and CNF/S ratios.

Synthetic nanocomposites using carbon nanostructures such as carbon nanotubes, graphene, or graphene oxide as the load-bearing units within a polymer matrix are promising structural materials due to their potential for high strength and stiffness. However, the mechanical properties of these macroscale composites are presently limited by many types of flaws and relatively weak interfaces, preventing them from achieving high strengths comparable to their parent nanostructures. Because these carbon-based nanofillers comprise of particles that are non-uniform in composition, structures, and morphologies, and their distribution within a composite are difficult to control, we choose to fabricate nanocomposites that are flaw-tolerant, rather than flawless. In this talk, we describe the fabrication, mechanical measurements, and structure-property relationships of multilayer graphene oxide-polymer composite films with alternating soft, crack-hindering polymer layers and stiff, load-bearing graphene oxide layers. This structure is inspired by that of sponge spicules[1], where periodic lamellae of soft protein and hard mineral hinder crack propagation, increasing strength and toughness[2,3]. We find multilayer films fabricated in this fashion have double the strength of pure graphene oxide films without sacrificing stiffness, and that employing an optimal polymer layer thickness can maximize both stiffness and strength. Finite-element analysis of the multilayer film reveals the stress redistribution that occurs around a broken graphene oxide layer, providing insights into the statistical nature of the strengths of these multilayer films. This work was supported by the ARO MURI (Award # W991NF-09-1-0541).
1. Woesz, A., et al., J. Mater. Res. 2006, 21, 2068-2078.
2. Fratzl, P., et al., Adv. Mater. 2007, 19, 2657-2661.
3. Kolednik, O., et al., Adv. Funct. Mater. 2011, 21, 3634-3641.

The huge diversity of hierarchical micro-/nano-scale rigid structures existing in biological systems is increasingly becoming a source of inspiration of materials scientists and engineers to create next generation advanced functional materials. Recently, accompanied with the development of nanotechnology, some biologically hierarchical rigid structures have been duplicated and mimicked in artificial materials through hierarchical organization of micro-/nano-scale building blocks. We will report several facile synthetic protocols for one-pot controlled synthesis of several kinds of unique nanoscale building blocks, including ultrathin nanowires, nanoplates, and magnetic nanoparticles, conducting nanocables, and carbon-based nanostructures. Then, we discuss how to assemble these nanoscale building blocks into ordered assemblies as well as their functionalities. These assembled structures based on bio-inspired approaches will find potential applications in different fields.

A recent theoretical insight (Alugrave; A., Engheta N., 2009) attracting attention finds that a symmetric cluster of metal nanoparticles (NPs), viewed as a “metamolecule,” may resonantly enhance local optical magnetic fields dramatically. The challenge to realizing such structures is the difficulty that traditional lithographic techniques face when assembling 3-dimensional (3D) clusters (Shafiei F. et al., 2013). The 3D nanoclusters are naturally formed with our bottom-up self-assembly techniques. We employ viral proteins as scaffolds (Soto C. M, Ratna B. R, 2010) to direct the metamolecule self-assembly because viruses (i) come ready-made at the correct size scale (10s of nm cores); (ii) can be made in large quantities with minimal defects and low cost, (iii) can be genetically or chemically modified to provide a range of desired symmetries and to tune the wavelength and strength of optically induce magnetic moment.
We present the preparation of nanoclusters using cowpea mosaic virus (CPMV) as a scaffold. CPMV was decorated with gold nanoparticles (Au-NP) of various sizes. Two methods were employed to obtain monodisperse Au-NPs and compared with commercial Au-NPs. Dynamic light scattering (DLS) was used to monitor the reaction progress and transmission electron microscopy (TEM) to image resultant CPMV nanoclusters. Electromagnetic simulations were performed using COMSOL multiphysics software package. Simulations show that the plasmonically coupled NPs of the CPMV nanocluster exhibit a resonance response in the visible. Simulations were compared with empirical spectroscopy results. CPMV nanoclusters showed a red shift of the Au-NPs plasmon peak along with a new broad band at longer wavelengths; agreeing with the simulations. The broad band is associated to the nanoparticles coupling in the CPMV nanocluster. These results open the possibility of producing metamolecules in sufficient amounts for the assembly of CPMV nanoclusters into novel optical materials.

The use of biomolecules as scaffolds for organizing inorganic and organic nanomaterials addresses the challenge of integrating multiple functional units with molecular-level control over their spatial arrangement. This approach has been used to build optically active nanostructures in which the plasmonic fluorescence is controlled via the precise arrangement of chromophores and plasmonic antennae. However, previous studies using metal nanoparticles less than ~60nm in diameter reported a predominance of fluorescence quenching due to the small scattering cross-sections of the particles.
In this talk, we will discuss our recent work on the design of hierarchical plasmonic structures built on virus capsid scaffolds and DNA origami tiles. In our design, the virus capsid enables precise control over the three dimensional arrangement of fluorescence dye molecules, whereas the DNA origami tiles provide well-defined control over the distance between the capsid and gold nanoparticles (AuNPs). Using finite-difference time-domain (FDTD) numerical simulations and multimodal single-particle imaging measurements, we show that the judicial design of these hierarchical structures can place a significant fraction of the dye molecules near the hot spots of the AuNPs and thereby effectively increase the fluorescence intensity within the typical AuNP quenching regime. The results also show that fluorescence enhancement is promoted by increasing the AuNPs size.
Our future studies will focus on improving the design of these hierarchical plasmonic structures by exploring an extended variety of metallic species, nanoparticle shapes, and spectral properties of the dye molecules. Identifying alternative viral capsid scaffolds with optimal geometry, rigid structural integrity, and versatile addressability is also currently underway in order to extend the function of future designs. We envision that this work will lead to a better understanding of the antenna effects of photon absorption and emission, allowing for future construction of multicomponent plasmonic systems based on bioinspired structured materials.

Patterned biological particles are widely observed in nature from pollen grains on the millimeter scale to viruses on the nanoscale. However the parallel synthetic fabrication of such precisely patterned three dimensional structures with soft materials such as polymers and gels which could provide significant value in biomanufacturing, drug delivery, aggregative self-assembly and the colloidal sciences is challenging. We describe the parallel synthesis of soft-polyhedra with precisely patterned biomolecules on their faces using a combination of top-down lithographic patterning, molding and bottom-up self-assembly methods. Polyhedra are the most fundamental solids that have been studied since the days of Plato over 2000 years ago. In nature, many viruses have polyhedral geometries and biomolecule patterns on viruses are important in host cell interactions and pathogenicity. In our approach, we utilize the self-assembly of plates by an origami inspired paradigm [1] as well as molding and contact printing to create these structures with a wide variety of soft-materials such as cross-linked gels, stimuli responsive polymers and even cell laden gels. We anticipate that due to the wide range of soft-materials, sizes, and topographic or biomolecule patterns that these polyhedra could be used in a wide range of applications.
References: [1] S. Pandey, M. Ewing, A. Kunas, N. Nguyen, D. H. Gracias, G. Menon, Algorithmic design of self-folding polyhedra, PNAS 108, 50, 19885 (2011).

Peptide driven synthesis and assembly of inorganic nanomaterials has received much attention in the field of materials science. While there is a large amount of literature available on the fabrication of nanoparticles and assemblies using peptides, comparatively little is known the nanomaterial&’s in-depth atomic structure. Such information is an important prerequisite for the design of peptide sequences which can ultimately result in nanomaterials with tunable properties. In this work, atomic-scale structural information was elucidated for peptide-capped Pd nanomaterials using extended X-ray absorption fine-structure spectroscopy (EXAFS), high-energy X-ray diffraction (HE-XRD), and pair distribution function (PDF) analysis. Peptide synthesized Pd nanoparticles have been previously created using the Pd4 peptide (TSNAVHPTLRHL) and were shown to perform Stille C-C coupling reactions on various aryl halides at high turnover frequencies (TOFs) with low Pd loadings under non-traditional ambient conditions. By substituting the histidines at the 6 and/or 11 positions to either weakly interacting alanines or strongly interacting cysteines different TOFs were observed for the coupling of 4-iodobenzoic acid with PhSnCl3. As all the Pd nanoparticles were approximately the same size, variations in catalytic activity must be influenced by structural variations imposed by the peptide and/or the peptide&’s orientation on the Pd surface. Using EXAFS, the local chemical environment of peptide capped Pd nanoparticles and pre-reduced complexes was probed and correlated their corresponding catalytic activity. HE-XRD patterns were also obtained for the peptide-capped Pd nanoparticles and analyzed in terms of their PDF. While all materials resemble the bulk fcc lattice, certain degrees of structural disorder are observed for each Pd nanoparticle system. Atomic-scale Pd nanoparticle data was obtained by modeling the PDFs using reverse Monte Carlo (RMC) simulations. Three-body and four-body correlation functions were derived from modeled Pd nanoparticles and used to describe differences in catalytic properties. Taken together, such analysis yields important atomic-scale structure information, which assists in the fundamental understanding of these materials&’ properties and which can be used to create Pd nanomaterials with tunable properties through peptide sequence design.

Bio-inspired materials and devices are attracting increasing interest
because of their unique properties, which have paved the way to many
significant applications. Ion channels that exist in living organisms
play important roles in maintaining normal physiological conditions
and serve as “smart” gates to ensure selective ion transport. Thus,
designing a system that simulates these complex processes in living
systems is a challenging task for nanoscience. The gating property
nanochannel is realized by modifying the surface with functional
molecules that can respond to external stimuli. Recently, we have
developed various responsive nanochannel systems which were controlled
by our designed biomolecules or smart polymers responding to the
single external stimulus, provided an artificial counterpart of
switchable protein-made nanochannels. Most recently, we developed
dual-responsive single nanochannel systems, and compared with the
single external stimulus systems, the present work is more complicated
and moves one step farther for the development of “smart” nanochannel
systems for real-world applications. These intelligent nanochannels
could be used in energy-conversion system, such as photoelectric
conversion system inspired by rhodopsin from retina or bR, and
concentration-gradient-driven nanofluidic power source that mimic the
function of the electric eels. Learning from nature is a constant
principle for there are numerous mysterious properties in nature,
which have developed over millions of years of evolution and will give
us inspiration to develop novel functional interfacial materials.

The unique properties of the kinesin/microtubule pair, where the kinesin motor protein uses energy harnessed by the hydrolysis of adenosine triphosphate (ATP) to move along microtubule filaments, makes it quite suitable in size for lab-on-a-chip devices; and therefore, a promising tool in the development of synthetic nano-machines.
In order to engineer tailor-made artificial transport systems capable of directional transport of nanoobjects in a cell-free environment, biotinylated kinesin protein can be functionalized with nanoparticles via biotin-streptavidin linkages. Relying on the ligand exchange method, magnetite (Fe₃O₄) nanoparticles were designed bearing a free amine surface that can be chemically linked to streptavidin and consequently, coupled to the kinesin motor protein.
The movement of hybrid Fe₃O₄ magnetic nanomaterial over microtubules filaments could be monitored under fluorescence microscopy by labeling the streptavidin linker with fluorescein, and accordingly, run lengths and velocities of engineered nanotransport devices were monitored. These experiments shed light on the transport of functional hybrid nanoparticles by kinesin-based molecular shuttles to be potentially employed as drug delivery systems.

Hemostatic materials, at exerting direct pressure to prevent bleeding, allow time to activate the intrinsic coagulation cascade of the organism, to achieve hemostasis. That is, they generate a mechanical barrier or a matrix to which platelets can adhere, stimulating coagulation. Composite nanofiber materials are attractive for creating new materials with new or enhanced properties compared with single materials. Poly (vinyl alcohol) (PVA) is widely used in biomedicine, due to its excellent water-solubility, high biocompatibility, hydrophilicity, as well as some mechanical properties, besides being a good stabilizer of noble metal particles. The incorporation of nanoparticles can improve the performance of the mechanical, thermal, optical, electrical, antimicrobial, antifouling and catalytic properties of a polymer. Compared with other nanomaterials, silver nanoparticles (AgNPs) have an excellent antibacterial action, damaging the membrane structure of bacterias and causing changes in their permeability and breathing, through the release of silver ions and the generated reactive oxygen species. Graphene oxide nanosheets (GrO) is used as a matrix can induce binding capability in AgNPs and thus enhance its antimicrobial activity.
In the present work, we will introduce a hemostatic material, consisting of PVA nanofibers obtained by electrospinning , to obtain enhanced mechanical properties and, at the same time, antimicrobial activity. The nanofibers are reinforced with the hybrid nanomaterial Graphene Oxide nanosheets/Silver Nanoparticles (GrO/AgNPs). The synthesis of graphene oxide sheets was achieved successfully by the modified Hummer's method. A novel environmentally-friendly method was successfully employed for the synthesis of silver nanoparticles, by using geranium extract as reducing agent and ethylene glycol. The results of UV-vis spectroscopy suggest that the synthesis method used to the hybrid material was adequate. Optimal conditions for the synthesis of AgNPs were achieved by changing the ethylene glycol by ethanol in both hydrothermal and reflux conditions. The hydrothermal yields a larger diameter of the nanoparticles and the hybrid material had a uniform distribution of the nanoparticles on the graphene oxide nanosheets.

Shape, size, and surface modification control functionality of metal nanocrystals in many applications. Metal nanocrystals of different shape from in-situ approaches facilitate the exploration of new functionality in sensors, catalysts, optic, and electronic devices while the underlying shape-directing mechanisms still remain poorly understood. Short polymers of naturally occurring amino acids have been employed as efficient regulating agents to engineer the structure of nanocrystals through recognition of crystallographic facets. A naturally selected peptide named T7 (Acyl-TLTTLTN-Amide) was reported to bind to platinum nanocubes, and to yield a high percentage of single crystalline platinum cubes in a reductive synthesis route. In this study, we explain the mechanism of specific cube recognition and of cube formation from cuboctahedral seed crystals using molecular dynamics simulation, synthesis, and characterization. The higher mobility of water molecules near the edges of nanocubes, compared to the center of the facets, as well as by a unique match of polarizable atoms in T7 (N, O, C) to the square pattern of epitaxial sites plays a major role for peptide adsorption onto {100} facets. These contributions support adsorption of peptide near the edges (-5.8±0.8 kcal/mol) while inner areas of nanocube facets and extended {100} surfaces repel the peptide at low concentration (+13±2 kcal/mol). In addition, the peptide concentration was found to be a crucial factor. On extended {100} surfaces, multiple T7 peptides interact with each other and turn repulsion into attraction upon increase in concentration. The main interaction mechanism of T7 with even and shaped surfaces is anticipated as soft epitaxy, supported by the charge-neutrality of the peptide (protection of the N and C termini by acyl and amide groups) and by the absence of thiol groups that could form covalent bonds. On cuboctahedral seed crystals, T7 peptides preferentially locate on {100} facets at intermediate surface coverage in correlation with a maximum yield of Pt nanocubes in reductive synthesis, while about equal distribution on {100} and {111} facets is found for low and high concentration. Selective stabilization of {100} facets is specific to peptide T7 and in contrast to another peptide S7 (Acyl-SSFPQPN-Amide) that strongly stabilizes {111} facets over a wide range of concentration in experiment and simulation. The visualization of facet preferences and estimation of binding energies of peptides on metal nanostructures in atomic resolution using the INTERFACE force field demonstrates considerable capabilities of high performance simulations.

Dental pulp stem cells (DPSCs) are ectomesenchymal cells that have been shown to be multipotent and capable of generating odontoblasts, osteoblasts, adipocytes and neurons. On tissue culture plastic these cells show a dexamethasone dependent differentiation, which we found could be alleviated by growth on thin films of spun cast polybutadiene. As we known, graphene, as a new biocompatible material, retains some unique properties such as high electrical conductivity, elasticity with the ability to absorb various molecules including potential inducers of differentiation. It therefore holds tremendous potential for a wide variety of biomedical applications. We are currently exploring the use of graphene and graphene oxide introduced into the media and incorporated into spun cast polymer thin films. Differentiation is being monitored immunohisotchemically (osteocalcin expression) and biomineralization is being assessed (Alizarin red and SEM/EDX). We have found no cytotoxic effects on DPSC with graphene added to the media at concentrations up to 0.1mg/mL.

Three-dimensional (3D) porous metal nanostructures gain increasing attention for their potential applications to energy systems, sensors, electronic devices, etc. However, efficient, robust immobilization of the nanostructures within 3D scaffolds is still very challenging. Here we introduce a facile templating method to synthesize and immobilize noble metal nanostructures using catechol-grafted polymer nanofibers as a bio-inspired reactive template. A redox-active polymer, catechol-grafted poly(vinyl alcohol) (denoted as ‘PVA-g-ct&’), is synthesized and electrospun into reactive nanofibers by electrospinning. The grafted catechol is inspired by mussel adhesive proteins, which mediate binding and reduction of noble metal ions on the nanofiber templates. Highly open porous silver nanostructures are spontaneously generated by simply immersing a PVA-g-ct nanofiber mat into an aqueous solution of silver ion precursors under ambient conditions due to the reducing capability of the grafted catechols, while gold and platinum ions are partially reduced and complexed with the nanofiber templates, requiring an additional thermal treatment for their complete reduction into solid metal nanostructures. In addition, silver-gold and silver-platinum hybrid nanostructures are generated using the pre-synthesized silver nanoparticles on the PVA-g-ct nanofibers by sequential treatments with metal ion precursors. We expect that the bio-inspired reactive nanofibers can be used as an attractive template for the synthesis and immobilization of metal nanostructures within 3D porous structures, providing a wide range of functional nanomaterials for biosensors, catalytic systems, and electronic devices.

Increased in vivo nanoparticle circulation times would be beneficial to sustained systemic drug delivery, active and passive targeting of both tumor-located and circulating cancer cells, bio-imaging, as well as the prevention of viral and bacterial spread. Accurate determination of mesoporous silica nanoparticle (MSN) biodistribution is often confounded by aggregation, which masks the behavior of individual nanoparticles and results in rapid uptake and clearance by the mononuclear phagocyte system (MPS). In mice, the notion that nanoparticles quickly accumulate in the liver, spleen, and kidney is widely accepted; however, by altering the size and surface chemistry of MSNs we are able to shift biodistribution systematically. MSN synthesis using a dual modification polyethylene glycol (PEG) plus trimethylsilyl chloride (TMS) enables the formation of particles that are uniform, nano-sized, and colloidally stable in diverse media, including simulated biological fluids. Using whole animal fluorescent imaging, fluorescent microscopy, TEM, SEM, and ICP-MS we demonstrate that 25 and 50 nm particles can remain systemically distributed, thereby minimizing their accumulation in MPS organs, as compared to 150 and 250 nm particles synthesized with identical surface chemistries. To further alter organ accumulation and extend circulation time via innate immune system evasion, we shielded MSNs with red blood cell derived membrane vesicles. To accomplish this, we fused membrane vesicles, derived from mouse and chicken red blood cells, to the surfaces of monodisperse 50 - 250 nm MSNs, characterized the nanoparticles, and measured circulation time and systemic distribution using both an ex ovo chicken embryo model and in vivo mouse model. Our results reveal the individual effects of particle size and surface chemistry on biodistribution and clearance.

Light triggered changes in biological molecules which enable various functions such as vision, photosynthesis and heliotropism have long inspired materials chemists to mimic these phenomenon&’s to create new functional materials and devices. The ability to detect and translate the conformational changes in the small molecule retinal into the macroscopic effect of vision exemplifies a very powerful and elegant approach to the design of new functional materials. Nanocarbon materials such as nanotubes and graphene, with their exceptional electrical conductivity, robustness and small size, have attracted interest as possible nanoscale replacements for inorganic semiconductors. We have demonstrated an optically active nanotube-hybrid material by non-covalent functionalization of single-wall nanotubes with an azo-based chromophore. Upon UV illumination the chromophore undergoes a trans to cis isomerization leading to charge redistribution near the nanotube. The resulting change in the local electrostatic environment led to a shift in the threshold voltage and increased conductivity of the nanotube. Graphene shares many of the same excellent materials properties as carbon nanotubes; however, unlike nanotubes, graphene can be grown over large areas with excellent control over uniformity and without concern for alignment and organization, which advantageously makes its processing more similar to that of traditional semiconductors and therefore also more industrially scalable. We demonstrated the reversible modulation of doping in graphene using light switchable azobenzene containing molecules tethered to the surface via π-π interactions with a pyrene group. As the molecules switch reversibly from trans to cis form the dipole moment also changes, and hence the extent of doping in graphene. The sensitivity of the readout by graphene in a given transistor architecture is striking, as a relatively small change in electrostatic potential due to isomerization of molecule results in a 40 times voltage amplification. We outline the characterization of these interfaces by Raman spectroscopy, electrical measurements, and by Second Harmonic Generation, to probe the molecular orientation, and charge transfer characteristics to gain mechanistic insight into this effect.

Polymeric membranes are a promising molecular separation technology, but current filtration membranes separate solutes by size, compounded in some cases by charge effects. They cannot effectively separate small organic molecules of similar size. In contrast, biological transport systems such as ion channels, porins and nuclear pore complexes exhibit exceptional separation selectivity based on specific interactions between the membrane nanochannels and a target solute. We aim to develop synthetic polymer membranes that separate organic molecules based on their chemical features, inspired by the structure of biological pores. These systems combine two important structural features to achieve high selectivity: 1. Constricted pores similar in diameter to the target compound (~1 nm for ion channels and porins); 2. Functional groups lining the pore that interact with the target during passage (e.g. spatially arranged hydrogen bonding groups in maltoporin LamB). We mimic this structure by synthesizing novel amphipilic comb copolymers that microphase separate to form ~1 nm nanochannels due to the immiscibility of the backbone and side-chains. The side chains contain functional groups able to preferentially interact with the solute through hydrogen bonds (such as ether oxygens or tertiary amines) and initiate a facilitated transport mechanism. We synthesized such copolymers with polyacrylonitrile by free radical and atom transfer radical polymerization (ATRP) methods. Solutions of these polymers are coated onto an ultrafiltration (UF) membrane support, to become the selective layer of thin film composite (TFC) nanofiltration membranes. Upon coagulation of the coating, microphase separation occurs between the hydrophobic backbone and hydrophilic side chains, as documented by differential scanning calorimetry (DSC). This phase separation allows the formation of a percolated network of nanochannels of the desired size, polarity and hydrogen-bond selectivity, through which only the target solute can selectively interact. The membrane nanostructures are characterized by X-ray scattering. Membrane selectivities are probed via diffusion tests of dye pairs, with similar size and shape but different hydrogen-bonding properties, such as phloroglucinol which contains -OH groups, and mesitylene which contains -CH3 groups instead. Diffusion kinetics is followed with UV-Vis spectrophotometry. We found that organic molecules that contain hydrogen bond accepting groups (e.g. -OH, -COOH) diffuse faster through these membranes than those that do not. These systems are promising first examples of membranes that separate small molecules based on their chemical features.

Introduction
To understand the role of physical property of microenvironment surrounding cells for changes in cellular functions, we prepared cytocompatible micro-sized hydrogels composed of bioinspired phospholipid polymer. This hydrogels could be formed spontaneously by mixing aqueous solutions containing poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-4-vinylphenylboronic acid (VPBA)] (PMBV) and poly(vinyl alcohol) (PVA). Moreover, the PMBV/PVA hydrogel could be reversibly dissociated by addition of natural sugar compound. Its crosslinking relies on specific covalent binding between VPBA units in the PMBV and hydroxyl groups in PVA. Because this crosslinking reaction occurs under physiological condition (neutral pH, room temperature), living cells can be encapsulated in the hydrogel without adverse effects. The use of microfluidic device allowed for encapsulating cells in the microgel and controlling cell number in the microgel. These microgels were suitable as matrices to determine the relationship between physical properties around cell and cellular functions (e.g., proliferation, differentiation). Here we will report, elasticity and molecular diffusivity of the PMBV/PVA hydrogels related to cell response.
Materials and Method
The molecular weight (Mw) and molar ratio of MPC/BMA/VPBA of the PMBV were 40 kDa and 0.71/0.13/0.16, respectively. The Mn of PVA was 4.2 kDa. Five-wt% PMBV containing cells and 1.0-5.0 wt% PVA in cell culture medium were introduced into microfluidics and mixed together to make microgels. Diffusion coefficient of fluorescence-labeled proteins in the microgels with varied pre-polymer concentration was measured by fluorescence correlation spectroscopy. Elastic modulus of the hydrogels was determined by dynamic mechanical analysis. Cell proliferation behavior was evaluated by using single HeLa cell in the microgel.
Results and Discussion
The MPC polymers are well-known to inhibit cell attachment and cell response on the surface. Therefore, PMBV/PVA hydrogel enables the specific evaluation of the physical effects on cell response in the absence of cell-matrix interaction. The microfluidics produced spherical hydrogels with the diameter of 10-100 µm, and encapsulated single to several cells in the microgels. Elasticity of the hydrogel increased from 24 to 367 Pa as the PVA composition increased. This range of elasticity was similar to that of fat tissue or brain. The diffusivity of the proteins in the microgel were in the order of 10-7 cm2 s-1, which is similar to that in the native extracellular matrix. While preliminary experiment revealed that cell proliferation behavior did not change in this diffusivity range. Therefore, elasticity can be considered as a primary factor in modulating cell proliferation. The PMBV/PVA microgel expects to be a potent candidate for artificial cellular microenvironment allowing for regulating cellular functions by changes in physical properties.

[Introduction]Tissue engineering is most usually assigned as the application of medical science and engineering principles in the design, erection, interpolation, growth and maintenance of living tissues. Normally, a three-dimensional structure, called scaffold, is necessary in tissue engineering applications since bioartificial tissues involve three-dimensional structures with cell multitude. The evolution of the field of tissue engineering goes in parallel with the coherent demand for new scaffolding materials with definite properties such as controlled porosity and pore size distribution, biocompatibility and biodegradation. Among these materials, natural polymers predispose especially interest because of their biocompatibility, biodegradation, and exuberance. Polysaccharides are natural polymers that include cellulose, chitin, and starch. Cellulose is the most abundant polysaccharide found on earth, but cellulose has many limitations in utilization and manipulation such as its poor solubility in water or organic solvent. We found that aldehyde introduced polysaccharide via Malaprade oxidation can be degraded at the glycoside bonds through the reaction with amino groups. In this study, we focus on the control of cellulose scaffolds degradation by oxidation and reaction with amine species.
[Materials and methods] 1-Butyl-3-methylimidazolium chloride, an ionic liquid, was used to dissolve cellulose at 100C and maintained at room temperature for 7 days, providing flexible cellulose hydrogels. The cellulose scaffold was modified and oxidized using periodate oxidation (Malaprade oxidation), oxidation of carbohydrate by glycol cleavage to provide dialdehyde. Aldehyde groups introduced into cellulose were quantified by simple iodometry. During immersion of the cellulose scaffolds in the amino acid solution, the mass loss of the scaffolds was evaluated and the molecular weight variation of the eluted oxidized cellulose was determined by gel permeation chromatography and mass spectrometry.
[Results and discussion] Porous cellulose hydrogel scaffold were developed by using ionic liquid as a solvent. The aldehyde groups were well introduced by periodate oxidation. The introduced aldehyde groups reacted with amino groups to form Schiff base. The cellulose scaffolds after oxidation degraded in the amino acid solution. And the degradation was controlled by increasing the concentration of periodate, time of reaction and concentration of amino acids. Partially oxidized cellulose is the chemical properties of the oxidized residues and, in particular, the hydrolytic lability that may provide a basis for biomaterial with increased biodegradability. The results indicated that cellulose scaffold completely degraded in 1% periodate with 5, 10, and 15% glycine, partially degraded in 1% glycine in 16 hours. Successfully we developed the cellulose scaffolds by controlling the degradation.

Carbohydrate-based polymers are widely used in biomedical applications, including drug delivery and tissue engineering. Though most polysaccharides used today are isolated from natural sources, synthetic polymers offer several advantages including control over molecular weight and distribution and the ability to modify the polymer at the monomer level. To this point, we have developed the synthesis of a new type of carbohydrate polymer using a ring-opening polymerization method, in which glucose is linked via an alpha-amide bond to give a poly-amido-saccharide (PAS). PASs maintain many of the features of natural polysaccharides, including a defined stereochemical conformation and pyranose rings in the mainchain, but the amide rather than ether linkage provides unique characteristics. Further modification of these chiral polymers via controlled oxidation of the primary alcohol to the carboxylic acid and a second polymerization of the initiating group to yield glycopolymers creates a variety of new materials with very different properties. The structure, thermal, and mechanical properties of these polymers are investigated, and their potential in different biomedical applications is assessed, particularly in the area of protein stabilization.

Glycerol based polymers are of wide spread interest for industrial, cosmetic, and pharmaceutical applications. Poly(1,3-glycerol carbonate) based biomaterials are being investigated as drug-loaded buttressing films for the prevention of tumor recurrence after surgical resection, nanoparticles for drug delivery, and coatings for prevention of seroma. Poly(1,2-glycerol carbonate)s, however, are far less explored. Herein, we report a facile and efficient method to synthesize linear atactic poly(1,2-glycerol carbonate)s using a readily available starting material benzyl glycidyl ether. We also report the hydrolytic kinetic resolution of benzyl glycidyl ether using Jacobsen&’s catalyst and subsequent polymerization to afford the chiral isotactic polymer. Poly(1,2-glycerol carbonate)s degrade significantly faster than poly(1,3-glycerol carbonate). The significantly increased degradation rate fulfills an unmet need for readily degradable biocompatible polycarbonates for the biomedical and pharmaceutical industry.

We have investigated a bio-resin made of a keratin and fibroin protein, which derived from feathers and animal fibers. Fine powder of these proteins can be resinified by hot pressing at 100-180°C after adding water. This resinification is attributed to the crosslinking reaction by the formation of dehydroalanine residues under hydrothermal environments. These bio-resins have excellent properties such as high glass transition temperature, thermal conductivity and mechanical strength. These bio - resins are suitable for environmental friendly materials for housing and electronic components. However, these protein powders are expensive.
In Japan, the amount of textile waste has reached 1.7 million tons/year, and most of them are incinerated or subjected to a landfill disposal. 20% of textile waste is reused and recycled as industrial dusting cloths, heat insulators for automobiles, refuse derived fuels and raw materials for nylon or polyester fibers. Therefore, we investigate the fabrication of bio-resins using textile wastes, wasted feathers and wool from poultry farms and meat processing plants, which contain keratin and fibroin protein.
In the case of wool, (1) unstained pure wool yarns were crushed using a planetary ball mill apparatus; (2) 15 wt% distilled water was added to the crushed yarns; and (3) the obtained material was heated to 130°C (pressure, 20 MPa; vacuum < 6.0 Pa) using a pulsed-electric current sintering apparatus, and then immediately cooled. Obtained bio-resin exhibits slight brownish transparent colort. After drying, the glass transition temperature of the bio-resin was measured using the TMA and its dielectric properties at an ambient temperature were measured using the parallel-plate electrode method. The glass transition temperature was found to be 165°C. The dielectric dissipation factor (tanδ) gradually increased from 0.02 to 0.05 with increasing the frequency from 10³ to 10⁷ Hz. The relative permittivity gradually decreased from 5 to 4 with increasing the frequency from 10³ to 10⁷ Hz. Further, the obtained bio-resin can be recycled via the mechanically crushing. The glass transition temperature and dielectric properties of this resin were comparable to conventional resins.
In the case of textile waste, twisted union yarns (60% silk and 40% cuprammonium rayon) and silk-mixed spun acrylic yarns (50% silk and 50% acrylic ester) were crushed and sieved to remove cuprammonium rayon and acrylic ester; (2) 20 wt% distilled water was added to the crushed yarns to obtain a slurry-like material; and (3) the obtained material was heated to 150°C (pressure, 20 MPa; vacuum < 6.0 Pa) by using a pulsed-electric current sintering apparatus, and then immediately cooled. The glass transition temperature and dielectric properties of the obtained resin were comparable to those of the resins obtained from wool and feathers. Moreover, the renewability of the silk fibroin resin was confirmed.

The integration of a tripeptide derivative, which is a versatile self-assembly motif, with a ruthe-nium(II)tris(bipyridine) complex affords the first su-pramolecular metallo-hydrogelator that not only self-assembles in water to form a hydrogel, but also exhibits gel-sol transition upon oxidation of the metal center. Surprisingly, the incorporation of the metal complex in the hydrogelator results in the nanofibers, formed by the self-assembly of the hydrogelator in water, to have the width of a single molecule of the hydrogelator. These results illustrate that metal complexes, besides being able to impart rich optical, electronic, redox or magnetic properties to supramolecular hydrogels, offer a unique geometrical control to pre-arrange the self-assembly motif prior to self-assembling. The use of metal com-plexes to modulate the dimensionality of intermolecular interactions may also help elucidate the interactions of the molecular nanofibers with other molecules, thus fa-cilitating the development of supramolecular hydrogel materials for a wide range of applications.

The practical use of chemical sensors is realized in a vast number of applications, such as in industrial processes, environmental studies, agriculture, clinical settings, and military technologies. These applications stimulate huge growth in research into all aspects of high performance sensing. Whilst huge advances in receptor and transduction principles have been made, the ability to detect multiple volatile vapors and trace level molecules in real time is still challenging.

The Naturally formed photonic structures in the wing scales of tropical Morpho Butterflies have begun to provide novel bio-inspiration within the sensing community. In our recent study we have shown that the local chemical environment within the iridescent scales of the Morpho butterfly strongly influences the reflectivity upon low-concentration vapor exposures. Multivariate analysis of the reflectance spectra arising from the preferential absorption of different volatile organic compounds (VOCs) reveals a selective vapor response. This naturally occurring polarity gradient within the hierarchical photonic structure offers exciting prospects for the detection of VOCs using a single functionalized nanostructure, rather than through traditional sensor array approaches.

Here we demonstrate the unique opportunities that arise from utilizing Morpho Nanostructures for sensing through experimental and theoretical results. The vapor-induced differential reflectance spectral features that arise through different incident angles and linear-polarizations will be shown.

Tubular architectures consisting of self-assembled bilayers or monolayers of rationally designed amphiphilic molecules, so-called organic nanotubes (ONTs) have proved to be of significant importance for potential biological, medical, and industrial applications [1]. In contrast to conventional lipid nanotubes with identical inner and outer surfaces, diverse chemical functionalization of the inner surfaces of the ONTs allows us to encapsulate, store, transform, sense, visualize, and to release biomacromolecular guests in the cylindrical nanospace [2]. Furthermore, self-assembled ONTs with 10 nm inner diameters and 1000 nm length can actually provide the confined water volume corresponding to 1 attoliter (aL) [10(-18) liter]. From this attoliter chemistry point of view, we are now focusing on the elucidation of meso-scale host-guest science and engineering by using solid ONTs of 10~100-nm inner diameters with well-defined dimensions and functionalities. Here we discuss current research achievements on the encapsulation, confinement effect, and nano-fluidic and release behavior of anticancer drugs and biomacromolecules in the ONT nano-channels.
Self-assembled ONT from 2-glucosamine derivative carrying the tetraglycine unit with carboxylic acid terminal were able to give a nanocontainer, in which the anticancer drugs (cis-dichlorodiamineplatinum, CDDP) are densely populated on the inner surfaces via endo-complexation. The size dimension of the container proved to be 14-nm outer diameter, 6.7-nm inner diameter, and several micrometers long. Then, we demonstrated efficient loading and prolonged release of CDDP by using the high-axial supramolecular ONT. Next, we found that well-defined inner diameters of ONTs proved to remarkably affect the resistance of confined proteins to heat and to a denaturant. We investigated the dynamic behavior of Green Fluorescence Protein (GFP) involving transportation, diffusion, release and stability in the confined nanospace by using ONT hosts with three different inner diameters (10, 20, and 80 nm). The ONT hosts we employed were prepared by self-assembly of 1-glucosamine derivative carrying an oligoglycine unit with amino terminal. By utilizing an endo-sensing procedure based on fluorescence resonance energy transfer (FRET) between GFP and the interior fluorescence acceptor immobilized on the nanotube inner surface, we directly detected GFP behavior in the nanochannels of the ONTs in real time. As a result, the 10 nm nanochannel allowed us to store GFP most stably and without denaturation under high temperature and high denaturant concentrations, probably due to the confinement effect based on rational fitting of the inner diameter to the size of GFP.
References
[1] T. Shimizu et al., Chem. Rev. 105, 1401-1443 (2005).
[2] N. Kameta et al., Soft Matter, 7, 4539-4561 (2011).

Carbon nanotubes (CNTs) uniquely provide the fundamental requirements for mimicking biological protein channels, which selectively transport chemicals through the cell membrane at rates orders of magnitude faster than a simple diffusion or Newtonian fluidic system. Incorporating comparable transport properties into a mechanically stable solid state device will not only eliminate expensive protein expression and separation steps, but can also provide a wide range of applications such as chemical delivery and sensing, energy generation, and water purification. The atomically smooth and inert structure of CNT walls allow for a nearly frictionless flow of molecules through the nanotube core over large lengths. For instance, water velocity in CNTs shows five orders of magnitude enhancement relative to other conventional materials of similar pore size, thus rivaling that of protein channels. In addition to fast flow rates, transport can be modulated by gatekeeper chemistry using steric hindrance, electrostatic attraction/repulsion, or biochemical state. The selectivity region can be precisely placed at the nanopore entrance by chemically functionalizing carboxylate groups formed at both ends from oxygen plasma cutting. In this study, by measuring the ionic current through individual single-walled CNTs spanning a barrier between two fluid reservoirs, we experimentally demonstrate the similarities between the highly selective and fast passage of ions through individual single-walled CNTs and protein ion channels. We also propose a theoretical model to explain the unique dependence of ionic conductance on electrolyte type and concentration in such systems. Fundamental understanding of nanofluidic systems is essential for elucidating the physical mechanism underlying significantly more complex biological nanochannels.

Carbon nanotube (CNT) pores give a structural and functional mimic of an ion channel, in part because smooth, narrow and hydrophobic inner pores of CNT are remarkably similar to the natural biological pores. Incorporation of CNT pores into the biologically-relevant environments and measurements of ion and proton transport in these assemblies would not only enhance our understanding of molecular transport in these materials systems, but also open up ways to develop novel bioengineering applications. We will describe incorporation of carbon nanotube pores into a lipid membrane and measurement of proton and osmotically-induced ion transport through these model nanopores using dynamic light scattering (DLS) experiments. We also discuss factors that govern and ion rejection in these structures and compare the results with modeling results and measurements in nanotube-based membrane structure. This research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, and the LLNL LDRD program.

Biomolecular unit cells can be described as small building blocks whose repetition can form the basis of a novel biomolecular material system. The biomolecular unit cell consists of a lipid bilayer interface formed at the contact of two aqueous droplets encased in lipid monolayers. The droplets are surrounded by a hydrophobic organic solvent (Hexadecane), and are sitting on fixed silver-silver chloride (Ag/AgCl) electrodes. Many types of biomolecules such as ion channels can self-assemble in the lipid bilayer interface. Therefore, the Droplet Interface Bilayer (DIB) has been extensively used to systematically study the activity of various biomolecules including alamethicin, bacteriorhodopsin, and many others. Accordingly, other types of biomolecules such as mechanosensitive (MS) channels self-assembled within the DIB should be able to respond to an expansion in the artificial membrane. And therefore can be used as a model system to understand how the structure of the protein and its incorporation into the unit cell affects its transduction properties. MS channels residing in the cytoplasmic membrane of Escherichia coli respond to a mechanical tension in the cell membrane, and fall under three categories according to their conductance level. MscL, the mechanosensitive channel of Large conductance, has been studied both in vivo and in vitro using patch-clamp methods.
This paper presents first attempts to study of the MscL channel activity in an artificial DIB system. A novel and simple technique is developed to characterize the behavior of an artificial lipid bilayer interface containing MS channels. The experimental setup is assembled on an inverted microscope and consists of two micropipettes filled with PEG-DMA hydrogel and containing Ag/AgCl wires, a cylindrical oil reservoir glued on top of a thin acrylic sheet, and a piezoelectric oscillator actuator. Using this technique, dynamic tension can be applied by oscillating axial motion of one droplet, producing deformation of both droplets and area changes of the DIB interface. The tension in the artificial membrane will cause the MS channels to gate, resulting in an increase in the conductance levels of the membrane. The results show that the MS channels are able to gate under an applied dynamic tension. Moreover, it can be concluded that the response of channel activity to mechanical stimuli is voltage-dependent and highly related to the frequency and amplitude of oscillations.

Understanding the structure-function relationships of biological materials can enable approaches in the design of functional materials for use in a variety of applications such as in sensing and electronics. Biological systems exemplify the utilization of specifically designed templates for building and tuning materials properties. The assembly of biomolecular building blocks into larger and ordered structures is highly attractive because it does not involve complicated pathways or external manipulation. Biomimetic approaches that involve the use of proteins, peptides and other biomacromolecules have been investigated by researchers to create hybrid materials. Our research activities are aimed at understanding of how biomolecules interact with abiotic surfaces, investigating structure-function relationships of biomaterials, and how they can be used in the creation of functional materials. In this talk I will describe some our recent work on understanding peptide interactions with materials as well some recent work on tuning the hierarchical organization of a biopolymer and its effect on mechanical properties.

Genetically engineered spider silk block copolymers are promising candidates to study the effect of block composition, sequence, and length on fiber formation. Spider silk block copolymers were prepared based on the assembly of two individual blocks, a hydrophobic poly-alanine rich block (A) and a hydrophilic glycine-rich block (B). The A block consisted of one polyalanine/polyglycine repeat (GAGAAAAAGGAG) responsible for β-sheet formation. The B block was composed of four GGX repeats, separated by the GSQGSGR sequence. Based on our previous work, we applied recombinant DNA technology to engineer the second generation of spider silk block copolymers H(AB)n and H(AB3)n to study the length effect on fiber formation. The constructs were cloned, expressed and purified and their secondary structures and morphologies were assessed by FTIR, SEM, and AFM. In terms of morphology, as the number of AB repeats increased, the transformation from disordered structures to nanofibrils occurred. For example, H(AB)12 block copolymer with Mw of 43.7kDa self-assembled into fibrils with an average diameter of 25 nm in aqueous media; whereas, H(AB)2 with an Mw of 11.6 kDa did not form particular morphologies. Moreover, fiber formation of H(AB)12 was induced by applying shear force in protein solution using an AFM tip. In addition the effect of solvent environment on structure formation was studied. We used water and 2-propanol to assess the solvent effect on structure formation. In the case of H(AB) 3 when 90% 2-propanol was used as a solvent, smooth round nanospheres were observed with an average diameter of 100 nm. Elongated microparticles were observed when water was used as a solvent for H(AB)3. This approach demonstrates successful implementation of our previously developed silk block copolymer strategy to regulate material features by manipulation of the block domains in spider silk-like copolymers.

Several living organisms exhibit remarkable moisture-resistant adhesion to a variety of substrata. Biomimetic adhesives that recapitulate the strong wet bonding strength, the robustness, and the structural and functional complexity of their natural counterparts would have broad applications in both technological and medical fields. Here, we demonstrate a genetic modular strategy for engineering underwater adhesives based on the fusion of mussel foot proteins (Mfps) from Mytilus galloprovincialis with CsgA, the major subunit of adhesive curli fibers from Escherichia coli. These fusion proteins self-assembled into hierarchical structures composed of cross β-strand fibrils, with disordered Mfp domains displaying external to the amyloid cores formed by the CsgA domains, as revealed by molecular dynamics simulations. Moreover, they also displayed intrinsic fluorescence and had wet adhesion strength that matched or exceeded that of naturally isolated and recombinant CsgA-based curli fiber and Mfps. The adhesive biomaterials based on combinatorial and modular fusion of diverse functional domains will find broad applications and provide insights into the mechanisms underlying natural adhesive systems

Tailor made biomaterials with tunable functionality are crucial for multiple applications, ranging from artificial tendons or ligaments to specialty ropes in parachutes, sporting goods and fishing nets. An emerging paradigm in designing such materials is the construction of hierarchical assemblies of simple building blocks into complex architectures with superior properties. Spider silk is the best example of naturally self-assembling polymer whose mechanical strength exceeds that of steel and Kevlar®. To help understand the relationships between primary sequence, composition, and repetitive segments, and the structure-function properties of synthetic fibers, we generated several bioengineered proteins by combining the consensus sequences from flagelliform (Flag) and major ampullate 2 (MaSp 2), from the golden orb weaver, Nephila clavipes. Proteins with basic repeats comprising the Flag-like [(GPGGX₁ GPGGX₂)₂; X₁/X₂= A/A or Y/S] motifs with the MaSp 2-like (linker-A₈) sequences have been cloned, expressed and purified successfully. With this example of relating sequence design (hydrophobic-hydrophilic segments), followed by expression (genetic design and synthesis), and processing (film and fiber formation), synergy among these methods is demonstrated for predictable material property outcomes. This study will provide a basis for future designs of smart biomaterials based on spider silk chemistries, with controlled structure-function relationships that dictate material properties.

Most organisms rely on proteins to create structural materials with specialized functions that surpass the capabilities of synthetic polymers. We work with several systems designed to recapitulate the unique features of biological protein-based materials using methods that allow their properties to be rationally engineered for desired applications. Some of the materials that will be discussed capitalize on controlled conformational bistability of allosteric proteins to create stimulus-responsive hydrogels and biosensors. Other materials will be presented that take advantage of proteins&’ and peptides&’ ability to self-assemble in order to create hierarchical order on the nano- and micro-scales. Finally, a biomaterials engineering platform based on curli, the self-assembling functional amyloid of E. coli biofilms, will be discussed. This project treats cells as foundries for the biosynthesis, assembly, and post-modification of modular surface coatings.

Numerous plants protect themselves from herbivores using different strategies. Often, secondary metabolites act as toxins [1]. For example, over 3000 species of higher plants use cyanogenesis. They are able to release HCN (hydrogen cyanide) from a cyanogenic precursor [2]. When the plant tissue is crushed, the cyanogenic glycosides are exposed to the enzymes which results in HCN-formation [3]. HCN itself is known for its toxicity and ability to protect the plant from herbivores.
~600 million tons of wheat are harvested per year. This makes it one of the world&’s predominant crops [4]. Pest infestation of cereal grains (like wheat) still constitutes a worldwide issue, especially in developing countries [5].
In this work, a nature-inspired protection concept was developed. Seeds unable of cyanogenesis are intended to get more resistant against herbivore attack by a compartment strategy. As a first step grains were coated with materials that allow HCN-production. Multi-layer seeds were prepared by dip coating and presented the following layers: (1) mandelonitrile lyase, (2) PLA (polylactic acid), (3) mandelonitrile in PLA, (4) pure PLA. As a proof of concept the obtained seeds were brought to germination within 4 days in a closed container. HCN was detected in concentrations (1.1 mmol kg^-1) known to have an effect on herbivores [6].
[1] S. Ibanez, C. Gallet, L. Després, Toxins, 2012, 4, 228.
[2] J.E. Puolton, Plant Physiol, 1990, 94, 401.
[3] E.E. Conn, Cyanogenic glycosides. In P.K. Stumpf, E.E. Conn, eds, The Biochemistry of Plants: A comprehensive Treatise, Vol. 7, Secundary Plant Products, 1981, 479.
[4] J. Ekboir, CIMMYT 2000-2001 World Wheat Overview and Outlook: Developing No-Till Packages for Small-Scale Farmers. 2002.
[5] T. Phillips, Midwest Biological Control News, Volume II, Number 10, 1995.
[6] C.A. Patton, T.G. Ranney, J.D. Burton, J- Amer. Soc. Hort. Sci. 1997, 122, 668.

At present, monitoring of air at the workplace, in urban environments and on battlefields, exhaled air from medical patients, air in packaged food containers, etc. can be accomplished with different types of analytical instruments. Vapor sensors have their niche in these measurements when an unobtrusive, low-power, and cost-sensitive technical solution is required. Unfortunately, existing vapor sensors often degrade their vapor-quantitation accuracy in the presence of high levels of interferences and cannot quantitate several components in complex gas mixtures. Thus, new sensing approaches are required with improved sensor selectivity. This technological task can be accomplished by the careful design of sensing materials with new performance properties and coupling these materials with the suitable physical transducers.
In this talk, we will provide an assessment of the capabilities of bioinspired nanostructures for selective vapor sensing. These sensing materials can operate with diverse transducers based on electrical, mechanical, and optical readout principles and can provide vapor-response selectivity previously unattainable using other sensing materials. This ability for selective vapor sensing provides opportunities to significantly impact the major directions in developments and application scenarios of vapor sensors.
We will further provide details of our approach for selective vapor sensing by taking advantage of the hierarchical photonic nanostructure formed in the scales of Morpho butterfly wings. Upon interactions with different vapors and mixtures of vapors, such photonic structure produces remarkably diverse differential reflectance spectra. Spectral, temporal, and polarization resolution of different vapors will be discussed in detail. The response selectivity of iridescent scales of the Morpho butterfly wings dramatically outperforms existing nano-engineered photonic sensors.

Wearable robotic systems such as powered prostheses, orthoses, and exoskeletons need feedback regarding the motion of the human host. As wearable robots become less rigid and more conformal, encoders and accelerometers become less viable as sensing mechanisms. Here we present our efforts to design and fabricate sensors to answer the need for conformal sensors that interface with and track the motions of a human. To that end we use hyperelastic silicone rubber elastomers embedded with microchannels filled with a liquid metal alloy as a sensing element. The need for robust sensors require careful design and an interface between soft (E asymp; 100 kPa) and rigid (E asymp; 1 GPa) materials.
The soft sensor incorporates several design features, including: the use of 3D printed molds for rapid prototyping, liquid metal conductors to comply to large deformations, integrated hook-and-loop (e.g. Velcro) to make the sensors modular, and a gradient of material stiffness to increase sensor robustness and reduce overall sensor stiffness. We fabricate the sensor through a process inspired from soft lithography and microfluidics: first casting liquid silicone rubber in 3D printed molds then laminating cured layers to create encapsulated microchannels which we finally inject liquid metal alloy into. The metal alloy we used is eutectic Gallium Indium (eGaIn), which we chose because of its high conductivity and very low melting point (10°C). In order to create a robust electrical connection we embed flexible circuits of 25 µm thick copper on 18 µm thick kapton. Finally, to create a strong mechanical connection between hook-and-loop and soft rubber, we used a discrete gradient of material stiffness and a fabrication process that interpenetrated the entangled fibers of the hook-and-loop with liquid silicone rubber.
The result of our efforts to date have been the creation of a strain gauge capable of safely being strained to 100% (extended to 80 mm) over 1000s of cycles and capable of maximum strains up to 400%. Use of the strain gauges on the body have also shown promise: they can withstand extensions twice that of what would be expected while being worn on the body and the sensors measured joint angles with maximum error less than 10° as compared with the industry gold standard, optical motion capture.

An electro-mechanical memory (EMM) - a material which can independently store and restore its electrical actuation response is an outstanding challenge in the field of .electro-active materials. The EMM is an actuator whose ionic response could be tuned or completely switched off, in a reversible fashion. The EMM material we will present combines the desirable features of both IPMC actuators and SMPs. It is capable of bending ionic actuation with low voltages (0-2 V), shape-memory actuation to >100 % strain, and programming/recovery in the 60-110 oC temperature range. Multiple states can be programmed and “recalled”. The ionic actuation amplitude decreases linearly with strain up to 70 %, and completely switches off for strain ge; 100%. Yet using the material&’s memory to restore the actuator to a previous state, restores the ionic actuation as well.

Stimuli-responsive materials have potential applications in robotics, biomedical devices and energy harvesting. The energy density of synthetic stimuli-responsive materials has been limited when compared to mechanical actuators. Assembling biological organisms with water-responsive structures into stimuli-responsive materials could potentially offer a solution to this problem. We present that the response of the spores of Bacillus to water potential gradients exhibit energy densities significantly higher than the best synthetic water-responsive materials [1]. We have characterized the maximum energy density, response time, and reversibility of spores with experiments on both individual spores and self-assembled micrometer- to centimeter-scale spore-based materials. Experiments on individual spores were carried out with atomic force microscopy. We created a thermodynamic cycle with a positive work output by controlling force and relative humidity applied to the spores. These experiments allowed estimating the maximum energy density of spores. We then assembled spores silicon microcantilevers and latex rubber sheets to observe actuation behavior of the resulting hybrid materials. We found a large energy density, high reversibility and a relatively fast response to variations in water potential. As an application of these hybrid materials, we have built an energy harvesting device where spores generate electricity from evaporation of water.
References:
[1] Ma, M.M., et al., Bio-Inspired Polymer Composite Actuator and Generator Driven by Water Gradients. Science, 2013. 339(6116): p. 186-189.

Solar and wind power are carbon-neutral, sustainable energy sources, but their intermittent nature requires a reliable method of storing energy. Catalysts that efficiently interconvert between electrical energy and chemical bonds (fuels) are needed for a sustainable and flexible energy supply in the future. Hydrogenase enzymes in nature catalyze the oxidation of H2 and the reverse, production of H2 by reduction of protons. The hydrogenases are based on iron or nickel. Electrocatalysts based on inexpensive, earth-abundant metals (“Cheap Metals for Noble Tasks”) are needed since low-temperature fuel cells generally use platinum, an expensive, precious metal. Biologically inspired synthetic complexes studied in our lab incorporate pendant amines into the second coordination sphere of metal complexes. The amines function as proton relays proton relays, facilitating intramolecular proton mobility, as well as the movement of protons between the metal complex and acids or bases in solution.
We are developing nickel(II) complexes with pendant amines that catalyze the oxidation of H2 at 1 atm. A related series of Ni(II) complexes have been studied in detail for electrocatalytic production of H2 by reduction of protons. Turnover frequencies greater than 100,000 s-1 were observed, though often at a high overpotential. Iron complexes with pendant amines on the diphosphine ligand are also being studied, showing that it is possible to rationally design catalysts based on abundant, inexpensive metals as alternatives to precious metals. Organometallic Fe(II) complexes derived from CpFe(diphosphine)H, with pendant amines in the diphosphine ligands, mimic the reactivity of [FeFe]-hydrogenase enzymes, leading to new iron catalysts for oxidation of H2.
Research carried out in the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, is funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

In recent years, the use of rare earth elements (REEs) has resulted in significant advances in the energy efficiencies of key technologies, such as motors and lighting. However, little attention has been paid to the source of the REEs and the methods by which they are produced. Industrial production of the REEs is especially challenging because they occur in ores together, and are chemically similar. Consequently, separation of an individual REE usually requires many stages (in some cases as many as 750) as well as the use of toxic chemicals. As an alternative, we are investigating biologically mediated REE recovery, which promises to be a sustainable and environmentally low impact approach to the separation and production of these critical energy materials.
As part of our studies, we have screened multiple different bacteria for their REE uptake and separation capacity and have discovered the common marine microbe, Roseobacter sp., is one that has enhanced REE biosorption properties; it removes greater than 95% of all REEs when exposed to a 10 ppb mixed REE chloride solution. Using this bacterium, we have discovered that different bacterial surface sites that bind REEs have varying acid dissociation constants, or different pH levels at which they protonate and desorb a bound REE. Washing REE-biosorbed bacteria with low pH solutions releases pH-dependent ratios of REEs, with lighter REEs desorbing at lower pH levels than heavier REEs. This biosorption/wash cycle can separate individual REEs from a mixed aqueous solution with separation factors greater than 5, nearly 4 times better than what is currently achieved in industrial practice. Furthermore, when grown in the presence of REEs, Roseobacter sp. fractionates the heaviest REEs from one another, resulting in separation factors greater than those in industry today for these heavy REEs that are traditionally the most difficult to separate.

Nowadays a great interest of application of biopolymers such as cellulose or lignin derivatives in the development of electrochemical devices can be observed; they are rather environmentally friendly, renewable and easy accessible materials. Their huge occurrence in nature and low cost improves also their attractiveness from the economical point of view.
Taking into account electrochemical demands, particularly in the field of energy storage, sensor applications and electrocatalytic properties, lignin derivatives seems to be especially profitable. Lignosulfonates being a water soluble by-products of pulp and paper industry, recently were used as a electroactive materials and showed strong electrocatalytic behavior toward biomolecule. This activity is attributed by existence of many phenolic and methoxyphenolic functional groups that can be easily converted into reversible quionone/hydrquinone redox moieties. Moreover, due to possession of negatively charged sulfonic groups may be treated as a polyanions and used as a dopants for conducting polymers. Thus, they open up new possibilities for the production of cost efficient, environmentally friendly, up - scalable and lightweight energy storage systems as well as enhanced electrochemical sensors.
The aim of present work is a synthesis of conducting composites based on lignosulfonates for electrocatalysis, potentiometric sensors and energy storage applications. For this purpose, relatively simple functionalization of conducting polymers such as: polyaniline, poly - 3, 4 ethylenedioxythiophene (PEDOT), polypyrrole has been applied, where during galvanostatic polymerisation, lignosulfonate acts as a doping agent. In all cases, significant improvement of surface confined redox signals has been observed, because of development of reversible couple assignable to quinone/hydroquinone system. Such designed materials can be used as electrocatalytic mediators for dihydronicotinamide adenine dinucleotide (NADH) and ascorbic acid. Moreover, the possibilities of using this composites as potentiometric sensors are widely discuss. The abilities to store an electric energy in redox active lignin derivatives are presented.

Energetic nanomaterials release a large amount of energy due to their composition and size, however, these properties are severely limited by the mass transport, diffusion distance, and poor assembly of reactive components. Alternatively, in nature, biology uses an assortment of biomolecules to overcome such limitations by precisely controlling the diffusion, binding, processing, and assembly of inorganic materials and components. We explored the use of a bio-enabled process to assemble materials with energetic properties. Proteins cages such as ferritin and modified viruses were employed as components that can either serve as enablers for assembling and/or as the source the constituent material. For example, protein cages loaded with ammonium perchlorate (AP) or iron oxide were assembled onto nano-aluminum surfaces to create a nanoscale bio-based thermite material. We achieved enhanced reaction rates and increased energy output of bioassembled materials when compared to heterogeneous mixtures. The approached described in our study could enable the development of safer and more efficient combustible materials.

To electrify future transportation, it will be necessary to find high energy density batteries for long-range driving applications. Li-O2 batteries are one of attractive energy storage systems since they can increase the energy density of batteries up to threefold (500 - 900 Wh/kgcell) that of current technology. To date, the charging of Li-O2 batteries remains a challenge since it involves the decomposition of Li2O2. The overpotential of charging ranges from 0.7 - 1.5 V depending on the conditions of discharge including the current density and depth of discharge. To achieve high round-trip efficiency of Li-O2 batteries, the underlying mechanism of Li2O2 decomposition needs to be understood so that ideal catalyst can be designed and selected.
Here we investigated the Li-O2 battery performance of transition metal oxide nanowire (MnxCo3-xO4, 0 le; x le; 2) catalyst electrodes fabricated by M13 virus. Highly packed surface protein of the M13 virus functioned as low energy barrier nucleation sites. Accordingly, this biotemplate directed various inorganic materials synthesis under environmentally benign conditions (room temperature, aqueous media) like nature does. In contrast to conventional high temperature and high pressure driven synthetic approaches used for battery electrodes, biologically mediated synthesis provides a new path for future green materials. This biological system has the added advantage of constraining the final products geometry to fix the nanowires (~1 mu;m of length, ~50 nm of diameter) making it easy to compare chemical and physical properties of inorganic materials. Since numerous material properties (e.g., surface area, catalyst geometry, chemical composition and electronic conductivity) affect the Li-O2 battery operation, constraining the catalyst structure into nanowire with the similar scale to M13 virus is beneficial to differentiate the critical factor effects on the Li-O2 battery performance. We observed different oxygen evolution reaction (OER) profiles depending on the specific Mn/Co compositions, and further improvements were obtained by controlling nanowire surface conductivities with Ni nanoparticle hybridizations. We expect that this biologically driven study will elucidate the OER mechanism thus facilitating the design of future catalyst electrodes for large capacity and high round-trip efficiency of Li-O2 batteries.

Complex nano/microstructures are of fundamental interest, and the ability to program their form has practical ramifications in fields such as optics, catalysis and electronics. We developed carbonate/silica microstructures in a dynamic reaction-diffusion system that allows us to rationally devise schemes for precisely sculpting a great variety of elementary shapes. Detailed understanding of the underlying buffering mechanisms allows us not only to program elementary shapes, but also steer the precipitating reactants into complex flowers, corals, vases, and patterns, with precise control over placement of stems, leaves, etc. via sequential combinatorial assembly of the developing shapes. These findings may hold profound implications for understanding and ultimately expanding upon nature&’s morphogenesis strategies, and outline a novel approach to use sequences of dynamic modulations of the environment to steer self-assembly processes as a route to advanced, highly complex microscale materials and devices.

Hydrogel provides hydrophilic environment internal structure by containing internal water. It created for the cell and protein denaturation is prevented. Because of these characteristic, hydrogel was widely used for protein, nucleotides, and cell delivery system. In case of scaffold, hydrogel requires to have connective micron-size pores to provide body fluids to cells survival. Some methods for preparing hydrogels has macroporous structure, freeze & thaw, gas blowing, micro-emulsion and cryogel. We use cryogel method for synthesis macroporous hydrogel. Cryogel methods use crystallizable solvents at below subfreezing temperature. Frozen solvent crystal exclude dissolved monomer and polymer so it can provide pores which are determined by freezing temperature. Monomer or polymer form hydrogel structure in non-frozen liquid microphase. These macroporous structure have connective network structure, it can provide instance external stimuli-response, increase loading efficiency, and raise survival rate by transport body fluids. Harvard group reported that macroporous alginate hydrogels containing iron oxide nanoparticles were used as a delivery carrier of drugs, proteins and stem cells. Macroporous alginate ferrogel display a controlled release of these materials under external magnetic field. Inspired by this work, ferrogels were prepared and their potential role as a stem cell scaffold was investigated.
In this study, macroporous polyacrylamide ferrogel was prepared by polymerizing acrylamide (AAM) and N,N&’-methylenediacrylamide (MBAAM) monomers in the presence of decanoic acid coated nano-sized iron oxide with ammonium persulfate and N,N,N&’,N&’-tetramethylethylenediamine redox initiating system.
Gelation was performed by cryogel method under the freezing condition around -20 oC and Decanoic acid coated iron oxide nanoparticles were homogeneously mixed in the porous hydrogel matrix. AAM-MBAAM hydrogel were synthesized first to confirm its macroporous structure. Acrylamide and N,N&’-methylenediacrylamide were polymerized with 2 wt% monomer concentration solution. Macroporous structure was confirmed by Scanning Electron Microscope and the average size of the pore was around 200 micrometer. We confirmed that copolymerization is available with UV observable acrylate monomer. Iron oxide modified AAM-MBAAM ferrogel was formed with the same method, only increasing monomer concentration to 3 wt%. Synthesized AAM-MBAAM ferrogel was shrunken and expanded by external magnetic field instantly. Prepared macroporous ferrogels can be used not only for cell delivery, but also for protein delivery and drug delivery.

Today, chemistry of materials relies strongly on rational design over “all length scales”, where final enhanced functionality will ensure the overall synthetic pathway to be applied. From this way of thinking has recently emerged the concept of Integrative Chemistry going beyond bioinspired materials.[1] This new transversal domain of chemical science can be defined as an “interdisciplinary tool box” where advanced functional materials bearing hierarchical structures can be tailored via the smart integration of soft chemistry-based pathways and the versatile processing conditions offered by soft-matter physical-chemistry. One synthetic path combines sol-gel chemistry with lyotropic mesophases and concentrated direct emulsions to promote inorganic Si(HIPE)[2] (the acronym HIPE relies for High Internal Phase Emulsion). Recently, we used Si(HIPE) macrocellular foams as hard template to produce the parent carbonaceous macrocellular foams, bearing standard application in Li-ion battery electrodes and chemical electro-capacitors devices, hydrogen storage when modified with Li(BH4), while promoting outstanding capabilities when used as bio-electrocatalystsor biocatalystwhen functionalized with specific enzymes.[3]
In this paper[4] we aim at presenting for the first time SiC/C composite foams prepared from concentrated emulsions by carbothermal reduction of biosourced precursors combining sodium silicate by lignin at 1400 °C. The composition of the materials was determined by XRD, FTIR and Raman analyses. Their porous structure was characterized by SEM, mercury intrusion porosimetry, and nitrogen sorption, while their thermal properties were measured by TGA and dynamic DSC. Concerning their heat transport properties, we found out that when the starting lignin content was increased, the final C/Si ratio, the specific surface area and the heat diffusivity increased as well. Its unprecedented high values were attributed to a cooperative effect between radiative heat transfer and the presence of partially graphitized carbon.
(1) Backov, R.; Soft Matter 2006, 2, 452.
(2) Carn, F.; Colin, A.; Achard, M.F.; Deleuze, H.; Sellier, E.; Birot, M.; Backov R. J. Mater. Chem. 2004, 14, 1370.
(3) Brun, N.; Ungureanu, S.; Deleuze, H.; Backov, R. Chem. Soc. Rev. 2011, 40, 771.
(4) Ungureanu, S.; Birot, M.; Vignoles, G.; Lorette, C. ; Sigaud, G.; Deleuze H.; Backov, R. Adv. Eng. Mater. 2013, DOI 10.1002/adem.201300015. Cover

The use of bio-design concepts is a promising way to the development of advanced materials. There are many works about bio-inspired engineering, which referred the production of hybrid structures using biological systems. Nowadays, one of the science fields that has attracted the attention is the micrometric and nanometric materials constructed from “biotemplates”. The potential use of these materials with complex morphologies linked to their high reproducibility and morphological control, put these materials in a prominent position in the materials chemistry. In this context, microtubules with self-assembled gold and silver multilayer were prepared using the fungi Aspergillus aculeatus as biotemplate. Furthermore, colloidal systems of gold and silver nanoparticles were prepared by the Turkevich method. Inocula of the fungi Aspergillus aculeatus were added in an Erlenmeyer flask containing Czapeck medium, which was removed after two weeks. In the next step, 100 mL of colloidal nanoparticles were added into the fungi flask and after 15 days, this colloid was removed to be replaced by a new one. As a result, two types of microtubules were prepared at different multilayer orders of gold and silver. Both colloidal nanoparticles were characterized by X-ray diffraction (XRD), UV-Vis spectroscopy and scanning electron microscopy (SEM) and, the microtubules, by scanning electron microscopy (SEM) and 2-D mapping by energy dispersive X-ray spectroscopy (EDX). The plasmom bands at 523 nm and 421 nm denoted the typical regions of gold and silver nanoparticles, respectively. In addiction, the XRD patterns confirmed the face-centered cubic structure of them. According to the SEM-EDX images of the gold and silver nanoparticles, which presented average size of 15 nm and 32 nm, respectively, they formed multilayers onto the hyphae. In other words, the final hybrid materials were obtained with good nanoparticles homogeneity and with a wall thickness varying between 150 and 300 nm. SEM images of silver and gold nanoparticles showed that there are different predominance of nanoparticles depending on the region where is the hypha. This is because the fungi growing in the colloidal dispersion after the removal of the first colloidal nanoparticles. Therefore, the formation of microtubules with multilayers of different metallic nanoparticles using biotemplates proved to be feasible with respect to its construction, with control of the thickness and good uniformity on the distribution of the nanoparticles.

Vacuum assisted filtration of graphene oxide yields paper-like layered thin films, which exhibits outstanding mechanical strength and stiffness. However, such graphene oxide papers disintegrate in wet condition, essentially losing all their mechanical merits. Herein, we introduce silk fibroin as a polymeric binder in the graphene oxide paper to physically crosslink the graphene oxide flakes by weak interactions, such as hydrogen bonding, hydrophobic interactions, and polar-polar interactions. In contrast to pure graphene oxide papers, such silk fibroin - graphene oxide papers show excellent integrity even soaked in water. The weak interactions are all self-restorable during straining so the toughness, modulus, strength are all improved manifold to 2.8 MJ/m3, 14 GPa, and 150 MPa, respectively. Moreover, due to the excellent biocompatibility and biodegradability of silk fibroin, the silk fibroin bonded graphene oxide papers potentially inherit the biodegradability, making it an ideal renewable high performance structural material in protective coating, load bearing, and flexible electronics.

Hot-press Assisted Slip Casting (HASC) process is a newly proposed technique combining two relatively easy and conventional material processing methods; hot-pressing and slip casting. This technique enables fabrication of organic matrix bulk composites reinforced with preferentially oriented, high aspect ratio fillers leading to a lamellar architecture resembling to brick-and-mortar structure of natural nacre. Although, HASC processing can be used to fabricate composites with wide variety of organic matrix-inorganic reinforcement combinations, in the scope of this study, epoxy matrix was reinforced with glass flakes with an aspect ratio of ~150. The alignment of glass flakes was achieved by forcing the liquid epoxy resin to flow out from the reinforcement-resin mixture through a porous filter which was driven by applied hot pressing pressures. Correlation between processing parameters, reinforcement content, reinforcement orientation and mechanical property enhancement of the fabricated composites was investigated.
In order to investigate the effect of interfacial compatibility on the mechanical properties of the fabricated inorganic-organic composites, glass flake surfaces were modified with aminopropyltriethoxy silane coupling agent. As received and functionalized flake surfaces were studied by X-Ray Photoelectron Spectroscopy (XPS) to confirm the success of surface modification. Beside the survey spectra, high resolution XPS spectra were also acquired to investigate the interaction between the glass flake surface and amino-functional silane coupling agent. Fabricated bioinspired bulk composite materials were characterized in terms of their microstructural features, architecture and mechanical properties. Microstructural characterization and fracture surface analysis of the fabricated composites were performed using Scanning Electron Microscope. For the mechanical characterization, three pointing bending and work of fracture tests were conducted.
Results indicated that with an optimum amount of glass flake content and brick-and-mortar like arrangement of the glass flakes obtained by HASC processing, nacre-like bulk lamellar composites reveal substantial improvement in strength and stiffness with respect to neat epoxy. The micro-scale brick and mortar hierarchical structure of these composites have led to high work of fracture values, even higher than that of the neat epoxy. This high work of fracture values can be attributed to crack deflection and flake pull-out mechanisms leading to torturous crack path and increase in energy absorption. Functionalization of glass flake surfaces with amino-functional silane improves the compatibility and interfacial bonding between the flakes and the matrix leading to further enhancement in the mechanical properties of composites having nacre-like architecture indicating the impact of interfacial bonding on the mechanical properties of fabricated bioinspired bulk inorganic-organic composites.

Bone is a composite of nano-crystalline hydroxyapatite (HAp) and type-1 collagen, wherein HAp crystals are deposited with their crystallographic c-axis in alignment with the collagen fibrils. This unique orientation is considered to be responsible for the superior mechanical properties of bone. Biomineralization, the process of mineral phase deposition in a multicellular organism is a highly controlled event that requires the presence of specific biological information. In the context of bone biology (chondrogenesis and osteogenesis) very little is known about the impact of the nano-crystalline HAp on fate and function of cell populations associated with bone repair. Therefore, development of biomimetic functional biomaterials can shed light into stem cell-material interaction as it pertains to regenerative therapies.
Past studies have primarily focused on preparing composites of sintered HAp with polymers and more recently efforts have been made to deposit micrometer-scale HAp phases on substrates such as polymer films and fibers. Here we investigated the role of biopolymers in controlling the evolution of HAp on polyethylene terephthalate (PET) fibers (cross sectional diameter = 20 microns), and have developed a novel and robust method for obtaining homogeneous biomimetic nano-HAp on polymer fibrils within 24 hours. A physisorption process was used to modify PET fibers using an appropriate polycation, and proteins that promote chelation of calcium. Using this strategy the deposition of biomimetic HAp layer 20-30 nanometer (nm) in thickness, and composed of 300-400 nm domains, has been achieved for the fist time. X-ray diffraction and transmission electron microscopy (TEM) reveal the nano-HAp phase is composed predominantly of crystals, 19 -119 nm (avg. 58 nm) in length, 18 - 64 nm (avg. 30 nm) in width, 1.69 - 5.90 nm (avg. 3.90 nm) in thickness, and that are oriented in the [002] c-crystal plane. This mimics the dimension and structure of HAp (~50 nm × 25 nm × 4 nm) found in bone. Furthermore, TEM analysis show significant orientation of the HAp crystals with the PET fiber suggesting that the fiber surface directs the nucleation and epitaxial growth of the nano-HAp phase. Currently studies are underway to ascertain how this biomimetic nano-HAp influences the proteomic profile in human chondrocytes and human mesenchymal stem cells.

Carbonate apatite (CAp) have been focused as an artificial bone substitute due to the similarity of the chemical composition with hard tissue. B-type carbonate apatite (B-CAp), which substitute carbonate ion for phosphate in the hydroxyapatite crystal structure, are expected to have excellent bioabsorbability. Porous hydroxyapatite (HAp) has been already applied for an artificial bone due to their high osteoconductivity. However, clinical researches demonstrated that the porous HAp substitute has less bioabsorbability. Hence, there are still strong demands to improve the bioabsorbability of the substitutes.
Recent researches on In vitro and vivo test of B-CAp ceramics showed that B-CAp ceramics become difficult to dissolve over time. This dissolution tendency is the critical defect in the application for an artificial bone. However, there are few researches to focus on the cause of this tendency. Therefore, in this study, we investigated the effect of the carbonate content on dissolution behavior, and consider what makes B-CAp ceramics become difficult to dissolve over time
The CAp powders were initially prepared by a wet method using Ca(OH)2 suspension and H3PO4 solution including different amounts of NaHCO3 as a carbonate source. Porous ceramics were fabricated by sintering the freeze-dried mixtures of the powders and gelatin composite. From X-ray diffraction measurements, all porous ceramics were identified as a single phase of apatite. Fourier transform infrared spectra indicated that the carbonate ions in their structures obtained were ascribed to the B-type substitution. The amounts of carbonate ions were analyzed with a thermogravimetry and the elemental analyses were with an inductively coupled plasma spectroscopy. All CAp ceramics had three-dimensional pore (over 100mu;m) based on gelatin structure. In addition, these ceramics had interconnective pores(around 40µm) which enable cells to access inside. In the dissolution test, each sample was immersed in acetate buffer for 180 min. The Ca concentration was measured with a calcium ion meter and the immersed samples were analyzed with a Fourier transform infrared spectroscopy. The results of in vitro dissolution test suggested that as the carbonate content is larger, the dissolution amounts are larger and the dissolution tendency of B-CAp diminish. Fourier transform infrared spectra indicated that the sample which became difficult to dissolve had a new peak at 1580 cm-1 unlike the other one.

The present work demonstrates that nanostructured middle-block sulfonated styrenic pentablock copolymer ionomer (SSPB)/sulfonated montmorillonite (s-MMT) nanocomposite membranes, incorporating bulky imidazolium ionic liquids (IL), play as novel air-working IPMC polymer electrolytes. The microphase-separated big-size ionic domains of the SSPB on the several tens nanometer scale and the role of s-MMT as an ionic bridge between the ion channels resulted in not only unexpectedly larger ion conductivity, larger air-working bending displacement and faster bending rate without conventional IPMC drawbacks, including back relaxation and a sacrifice of mechanical strength, but also higher energy efficient actuation than Nafion. Interestingly, the bending displacement, bending rate, and charge-specific displacement of the nanocomposite IPMC increased with the increase in bulkiness of the ILs because of the strong ion pumping effect of the bulky immidazolium cations in the size-matched big ion channels of the nanocomposite membrane.

Molecular composites, whether biological or synthetic, can be considered as fundamental hierarchical systems due to the fact that they have been formed, either intentionally or unintentionally, by individual components. As all structures there is a need for the distinct material elements to behave synergistically. This is clearly shown in Nature, where the double stranded constitution of DNA is a well-known fact, however it is the highly cross-linked helical structure that shows potential as a structural material at a nanoscale. In a synthetic environment cooperativity has been demonstrated in a small sample, i.e. polyelectrolytes and hydrogen graphene oxides. The incorporation of the individual components within functional materials requires knowledge of the mechanical cooperativity between the components. This cooperativity can be seen as the optimization of contact, adhesion and/or deformation between the interfaces. Mechanical cooperativity can be thought of as the equivalent behavior between components and the system. This concept however, even though explainable, is hard to quantify. We propose to define molecular cooperativity through the development of geometric metrics, extended from polymer science. Here, we define and exploit a differential gyration tensor of a system and explore the use of universal shape ratios to conclude whether the system is behaving as a cohesive unit. A system of ideal dual cross-linked chain molecule systems through molecular dynamics is considered, where the number of defined cross-links determine the cooperativity between the chains. We study the cooperativity between the chains by utilizing shape ratios such as slip, asphericity and Euclidean norm as metrics.

Bioinspired, directional liquid flow on asymmetric structures has recently studied for water collection or guiding liquid in microfluidic channels. Since wetting properties of liquid is governed by the chemistry and geometric structures, the directional flow has been achieved by chemical gradients or asymmetric micro- or nanostructures. Here, we present a directional liquid flow on asymmetric prism arrays (Two Face Prism Array) fabricated by a replica molding of polymeric materials and oblique metal deposition on one face prism arrays. The liquid on asymmetric structures is pinned at edges and moves toward the direction of low critical contact angle. The direction of liquid flow could be switched by exploiting the amplification of wetting properties on roughened surfaces. Also we demonstrate a thermo-responsive switching of flow direction when using thermo-responsive polymers (poly N-isopropyl acrylamide; PNIPAAm). Furthermore, the asymmetric prism array shows directional optical properties such as directional transmission. We will discuss a fabrication method by physically asymmetric ratchets for the directional liquid flow by using optically asymmetric prism arrays.

We would like to demonstrate a novel type of surface-tention-confined microfluidic (STCM) system called “polydopamine (pDA) microfluidics”. It is a pump-free, two-dimensional microfluidic system, energy efficiently operated only with gravitational force. The pDA microfluidic device is fabricated by introducing hydrophilic pDA micro-patterns on nanostructured, superhydrophobic anodized aluminum oxide surfaces. On the pDA microlines, movement and mixing of droplets are precisely controlled in an energy-efficient manner by gravity. The pDA coating, inspired by mussels' robust adhesion on versatile substrates, was utilized to stably and permanently modify the superhydrophobic surface. The flow rate of pDA microfluidics was about 30 mu;L/s, faster than that used in conventional microfluidic systems (~0.5 mu;L/s), which is suitable for large volume applications. The pDA microfluidic device was applied as a rapid mixing device to monitor structural changes of photoactive yellow protein (PYP) and as a micro-reactor for the synthesis of monodisperse gold nanoparticles. The pDA microfluidic device is a promising candidate for a new type of microfluidic systems that is potable with extremely low energy consumption for operation.

Development of robust strategies for the engineered self-assembly of functional synthetic materials is a major challenge in advanced materials engineering. Biomimetic materials such as synthetic polypeptides and peptide-polymer conjugates serve as model systems that provide insight into the design and engineering of materials with predictable functional properties. Recent advances in synthetic bioorganic chemistry enabled increased control over chemical architectures, thereby facilitating the self-assembly of synthetic biopolymers into complex structures. However, the level of complexity of synthetic materials has yet to match those attained by natural polymers (e.g. DNA and peptides) that deterministically self-assemble into functional, three-dimensional hierarchical architectures. As a consequence, directed assembly techniques have emerged as potential new routes towards building supramolecular structures consisting of small molecules, oligomers, and polymers.
In this work, we report the fluidic-directed assembly of aligned pi-conjugated oligopeptides using a tailored laminar flow called planar extensional flow. Prior methods for fluidic-directed assembly have mainly relied on laminar co-flowing streams with uniform fluid velocities, which precludes fine-scale control required for nanostructure alignment. Here, we capitalize on planar extensional flow to induce alignment of underlying material suprastructures due to a dominant extensional/compressional character for this flow type. We demonstrate that our microfluidic-based method enables reproducible ‘triggering&’ of assembly, along with reliable formation of aligned hierarchical constructs that do not form spontaneously in solution. Alignment of assembled materials is demonstrated using fluorescence spectroscopy, fluorescence polarization microscopy, and fluorescence lifetime imaging microscopy as characterization methods. In this way, fluidic-directed assembly of supramolecular structures allows for unprecedented manipulation at the nano- and mesoscale, which provides rapid and efficient control of electronic or optoelectronic materials properties.
Marciel, et al., 'Fluidic-directed assembly of aligned oligopeptides with pi-conjugated cores', submitted (2013).

The integration of optofluidics and soft materials has ushered in a new generation of flexible devices for drug delivery, biosensors, and tissue engineering. These devices are biocompatible and allow complex control of device dynamics using fluidic and pneumatic controls. Importantly, these devices could be combined with synthetic biological systems to reduce the complexity of fluid systems while enhancing the control of the devices through exploitation of complex genetic controls in synthetic cells. Here, we take the first step towards such bio-opto-fluidic systems by constructing a hybrid device that consists of soft materials, synthetic bacteria, fluidic systems and electronics. Specifically our device consists of a flexible polydimethylsiloxane (PDMS) chamber for culturing synthetic Escherichia coli that expresses green fluorescent proteins (GFP) and a flexible electronic layer housing an LED with an emission spectrum peak at 395 nm. The PDMS chamber has high gas permeability that facilitates aerobic cell growth conditions, high translucence that allows for optical control of synthetic bacteria, and high viscoelasticity that provides mechanical versatility. We demonstrated that bacteria can be excited internally by an electronic component without sacrificing the flexibility and transparency of the device. We have also shown that isopropyl β-D-1-thiogalactopyranoside (IPTG) can be delivered via micro channels over a flexible micro-porous PDMS membrane to modulate gene expression of an E. coli strain inside the device. Furthermore we optimized the geometry of the device with respect to bacterial growth rates, fluorescence expression, and fluid flow properties. Finally, we tested the device during mechanical deformation by bending to demonstrate the robust function of the device in strain-induced conditions. Our work would have wide impact on the development of the next-generation bio-opto-fluidic devices and the integration of synthetic biological systems with soft electronic materials.

Advances in microfluidics are revolutionizing many disciplines, such as molecular biology, drug discovery, medical diagnostics, and materials science. Despite their significance and over two decades of research, the fouling of microfluidic networks when components from fluids irreversibly adhere to channel surfaces, remains a challenging and unresolved issue. Various strategies have been proposed to prevent surface fouling, such as using low surface energy materials to fabricate the microfluidic channels or chemical modification of material surfaces, but these approaches have not effectively resolved the problem. To address the challenge, here we report a new strategy to create universal antifouling microfluidic networks that show an outstanding inertness to various chemicals and organic solvents, resist adhesion from particles and proteins to complex fluids such as whole blood. Our approach—inspired by natural tubular organs—could provide a platform for many applications of microchannel systems and accelerate the development of high-performance microfluidic devices.

The stability of the lubricant/liquid interface is critical to minimizing lubricant loss and increasing the long-term functionality of Slippery Liquid-Infused Porous Surfaces (SLIPS) as omniphobic, pressure-resistant anti-fouling coatings. In this work, we examine the stability of different types of SLIPS lubricant/liquid interfaces under various flow conditions using both simple and complex liquids. Using a combination of gas chromatography, confocal microscopy, and computer modeling, we show that the choice of flow rate, lubricant type, and underlying substrate can have an effect. These results further the understanding of the optimal operating conditions of these materials and will aid in the further design of devices incorporating SLIPS technology.

Forcing hydrophobic particles to be dispersed in water is a common requirement for numerous applications from drug delivery to oil recovery. Such dispersions are typically achieved by using surfactants or polymers that “camouflage” hydrophobic surfaces with hydrophilic groups. Aqueous dispersion of hydrophobic particles without the use of any surfactants has both technological and academic significance. In this study, we demonstrate that aqueous dispersion of hydrophobic particles without any chemical canopy is indeed possible with reengineering of the interfacial topography. We sculptured the surface of a polystyrene microsphere to feature hydrophobic and rigid ZnO nano-spikes. The Hedgehog particles (HHPs), reflective of its morphology, forms a three-phase interfacial shell; radially distal portion occupied with water and the proximal portion trapped with air both of which are interdigitated with ZnO nano-spikes. We believe the aqueous stability of hydrophobic HHPs is due to its comparable density to the medium and increased charge repulsion due to high surface area. Furthermore, we demonstrate biomedical applications where we anchored the hydrophobic HHPs onto the cell membrane which opens up the possibilities of unconventional ornaments of biological cues onto the cells and of increased complexities in cell-cell signaling.

Some natural peptides self-assemble to produce complex structured materials in various media. Diphenylalanine (FF) is one of the widely-studied short peptide producing nanotubes and nanorods through the evaporation-induced self-assembly (EISA). These FF nanotubes have been used as templates to produce diverse conductive materials by additional deposition of metal clusters. However, the metal deposition process is inconvenient process resulted in uneven and discontinuous metal layers. To overcome this issue, we developed a novel FF-mimicked organic molecule with self-assembling property. The new molecule contained pyrrole ring as a hydrophobic group and this pyrrole groups were polymerized to give electrical conductivity after EISA producing microrods. Through the spectroscopic investigation, the pyrrole ring stacking is one of the key driving force leading rod-like assemblies during EISA process. After the microrod production by the self-assembly, the surface-exposed pyrrole groups were polymerized by the oxidant to produce organic conductive microrods. Conductivity of the produced microrods was comparable to that of other organic conductive materials reported. Additional analysis on the polymerized microrods proved that the polymerization was taken place only at the surface of the microrod and the surface became sticker after the polymerization. This study proved the concept of self-assembly and subsequent surface treatment to produce functional materials and showed that diverse designer functionality could be incorporated to the self-assembling molecule.

Inspired by nature, biomimetic synthesis techniques utilize biomolecules and synthetic analogs to produce materials with controlled chemistry, morphology, and function. One of the common characteristics of biomimetic processes is the generation of hybrid materials (composites) composed of mineral/biomolecule. These unique hybrid materials may possess and synergistically combine the activities of both the mediating biomolecule and the synthesized inorganic. In this presentation, we will report on the biomimetic synthesis and development of hybrid materials that display potent antimicrobial activity. Broad spectrum bactericidal/sporicidal activity is added to the synthesized materials through the chlorination of the nitrogen moieties present in the metal oxide-entrapped proteins and peptides to produce halamine compounds. Our results demonstrate that chlorinated biomimetic materials induce >5 Log reduction in the colony forming units of Escherichia coli, Staphylococcus aureus, and Bacillus thuringiensis cells, as well as B. thuringiensis spores within 10 min of organism-material contact. The effects of materials processing on the photocatlytic/antimicrobial activity of biomimetic TiO2 will be discussed.

We demonstrate the dual magnetic and light responsive nature of hybrid mesophases constituted by Fe3O4 nanoparticles dispersed in lipid-based lyotropic liquid crystals. When subjected to an external magnetic field above the order-disorder transition of the mesophase (i.e. in the isotropic state), the nanoparticles aggregate and orient along the magnetic field direction, and upon cooling the system through the disorder-order transition, the nanoparticle aggregates drive the orientation of the mesophase via heterogeneous nucleation [1]. The system is also shown to respond to the exposure of visible light, with order-disorder transitions in the lipidic mesophase triggered by Fe3O4-induced photothermal effect [2]. Both the orientational order and the photothermal effect of the hybrid mesophase can be tuned by the nanoparticle concentration, offering a general route for controlled assembly of complex fluids with combined magnetic and light responsiveness. We finally show how this unique system can be used to design stimuli-responsive anisotropic physical properties and we demonstrate this feature by illustrating the effect on the anisotropic diffusion of drugs within a columnar hexagonal mesophase embedded with Fe3O4 nanoparticles [3].
Literature:
1. Vallooran J. J., Bolisetty S. and Mezzenga R. Macroscopic alignment of lyotropic liquid crystals using magnetic nanoparticles. Adv. Mater. 2011, 23, 3932.
2. Vallooran J. J., Handschin S., Bolisetty S. and Mezzenga R. Twofold light and magnetic responsive behavior in nanoparticle-lyotropic liquid crystal systems. Langmuir 2012, 28, 5589.
3. Vallooran J. J., Negrini R. and Mezzenga R. Controlling anisotropic drug diffusion in lipid-Fe3O4 nanoparticle hybrid mesophases by magnetic alignment. Langmuir 2013, 29, 999.

Structured composites or hybrid materials with networks of interconnected interfacial layers can be tailored to regulate mechanical, chemical, acoustic, adhesive, thermal, electrical and optical properties of the material. The ability to transform the interfacial layer geometry via deformation-induced wrinkling and hence create reversible wrinkling patterns in cellular structured composites is shown through modeling and experiments. The deformation-induced pattern transformation can be used to regulate other properties and functionalities. The characteristics of the wrinkling and the instability modes were investigated as functions of network geometry and material composition. Analytical and finite element models were developed to capture various aspects of the wrinkling mechanism, and the overall structural response was studied under different loadings. Mechanical experiments were designed to further explore the modeling results. Exemplary patterned composite materials consisting of various geometries of networked interfacial layers within a soft matrix were fabricated using multi-material 3D printing and other methods. The experimental and numerical results were consistent with the analytical predictions demonstrating the ability to predictively design these transformative hybrid materials. The results provide the ability to derive biomimetic principles for active and multi-functional hybrid materials or actuating devices, or functionally graded materials. The ability to actively alter the cellular-network structure can enable on-demand tunability of different functions to provide, among others, active control of wave propagation, mechanical stiffness and deformation, and material energy absorption.

We present a versatile colloid-based approach for the large-scale synthesis of a new family of hybrid bioorganic-inorganic nanocomposites with an unprecedented control of the texture and morphology [1].
This approach combines the self-assembly properties of polysaccharide α -chitin nanorods (bundles of monocrystals with D = 3.2 ±0.6 nm) [2] with the flexibility of sol-gel processes involving siloxane oligomers. The stable suspensions of the two colloids, chitin nanorods and siloxane oligomers, undergo an isotropic / nematic transition when concentrated beyond ca. 2%. The ordered phase exhibits optical birefringence, and is highly responsive to the application of external fields (shearing, electric, magnetic). The nano-composites can be uniaxially aligned over millimeters by applying a strong (9.4 T) magnetic field during solvent evaporation across the sol-gel transition. Evidences suggesting the formation of chitin-silica hybrid colloids are being assessed by a combination of spectroscopic (NMR, XPS) and diffusion techniques (SAXS, MALLS). Besides, microparticles have been obtained using spray-drying processes, with mean diameters in the 2-3 micrometer range.
We also show that the characteristics of the silica-chitin nano-composites (morphology, texture, birefringence) can be transferred to their mesoporous counterpart by simple calcination [1,3], with pore diameters in the 4-8 nm range and specific surface areas up to 450 m2.g-1. For heterogeneous catalysis applications (selective oxidation), titanium alkoxides have been introduced to form mixed oxides SiO2-TiO2 (Ti/Si < 0.1). The dispersion of Ti sites can be tuned through synthesis conditions.
Latest results about chitin and silica colloidal self-assembly, materials synthesis and characterisation, and catalytic applications will be presented.
[1] B. Alonso, E. Belamie, Angew. Chem. Int. Ed., 2010, 81, 8201-8204; [2] E. Belamie, P. Davidson, M. M. Giraud-Guille, J. Phys. Chem. B, 2004, 108, 14991-15000 ; [3] E. Belamie, M. Yu. Boltoeva, K. Yang, T. Cacciaguerra, B. Alonso, J. Mater. Chem., 2011, 21, 16997-17006.

Natural composites like seashells, teeth and bone are made of soft organic and hard inorganic building blocks assembled into unique hierarchical architectures. The ubiquitous micro- and nanostructures of such natural materials lead to outstanding mechanical properties and find no counterparts within man-made composites. In this talk, I will present a new approach to obtain polymer-based composites exhibiting bioinspired deliberate orientation of reinforcing particles using ultra-low magnetic fields. The method relies on coating of non-magnetic anisotropic particles with minimum concentrations of iron oxide superparamagnetic nanoparticles (< 0.1 vol%). This enables magnetic control over the orientation of the coated anisotropic particles in a fluid, which can then be consolidated to form strong composites. Our ability to tune the position and orientation of reinforcing particles within a polymer matrix can lead to heterogeneous structures with unusual out-of-plane stiffness, hardness, wear resistance, tailored local mechanical response and shape-changing effects. Such bioinspired synthetic composites might help address some of the limitations of current composite technologies and can potentially be used as model systems to investigate the design principles of biological materials.

Self-assembly of protein matrices and subsequent mineralization is a widespread paradigm in the biological production of hard materials. The architecture of the underlying matrix imposes order on the nucleating mineral phase. The resulting structural complexity and mechanical properties are unparalleled in current synthetic approaches. To understand the underlying physical controls governing matrix assembly and subsequent mineralization, and to develop an ability to manipulate these processes, we have investigated a range of biomolecular and biomimetic systems using in situ techniques of AFM, TEM and dynamic force spectroscopy (DFS).
Our results on S-layer proteins and collagen reveal the key role played by conformational transformations in controlling the pathways and kinetics of matrix assembly. Investigations of assembly by biomimetic polymers show that small changes in sequence can alter the final pattern of organization or completely prevent the system from achieving order. Modification of surfaces through adsorption of ions or creation of block copolymer patterns leads to changes in assembly due to surface-protein interactions, while assembly in all systems is highly dependent on solvent composition. We consistently find that the pathway to the final ordered state in both natural and biomimetic protein systems passes through transient, less-ordered conformational states. Thus the concept of a folding funnel with kinetic traps defined by an energy landscape influenced by sequence and solvent interactions is as applicable to matrix self-assembly as it is to protein folding.
Analysis of matrix mineralization reveals two different styles of nucleation. In the case of proteins or biomimetic polymers that self-assemble into ordered structures, nucleation patterns reflect the underlying order of the matrix while, at least in the case of collagen, nucleation rates are enhanced through a reduction in the interfacial energy. In the case of polystyrene sulfonate, which forms disordered aggregates through complexation with calcium, nucleation appears to occur randomly within the aggregates. Taken together, these results provide new insights into the mechanisms controlling formation of biological and biomimetic composites, from assembly of the initial matrix to the formation of the final mineral phase.

The structure of materials invariably defines their mechanical behavior. However, in most materials, mechanical properties are controlled by structure at widely differing length scales. Nowhere is this more apparent than with natural materials. Bone, dentin and nacre, for example, are sophisticated composites whose unique mechanical properties derive from hierarchical designs that span nanoscale to near-macroscopic dimensions. Unlike engineering composites where properties are invariably governed by the law of mixtures, the mechanical properties of natural composites like nacre are far greater than their constituent phases. However, actually making such materials synthetically has proved to be very difficult, particularly in bulk form. Here we describe an approach to making synthetic bulk ceramic-polymer or ceramic-metal structural materials in the image of Nature with unprecedented strength/toughness properties. As in nacre, our bio-inspired ceramics have a lamellar or ‘brick-and-mortar&’ structure, where the ceramic phase provides for the strength. However, without a means to locally dissipate high stresses these materials would be brittle. The inclusion of a small fraction of a polymer or better still a metal as a “compliant phase”, which is not load-bearing but, like dislocations in metals or microcracking in bone, serves to enhance toughness by relieving locally high stresses. We have developed alumina ceramics containing small fractions of PMMA as a compliant phase, which we fabricated using controlled freezing of ceramic-based suspensions in water (freeze casting). The resulting properties of these bio-inspired alumina ceramics were remarkable, with at best toughness values exceeding 30 MParadic;m. Whereas the compliant-phase alum na ceramics were designed for high toughness, we have also developed biomimetic SiC/PMMA hybrids with structures tailored for higher strength. Results for lamellar structures indicate that the SiC hybrids are not as tough as the alumina hybrids; nevertheless they are five times tougher than commercial SiC (Hexaloy) and as tough as any SiC reported to data, achieved through mechanisms of crack deflection, pull-out and intense viscoplastic shear in the compliant layers. However, the greatest potential for developing new high-performance materials may lie with the use of ductile metal ‘mortars&’. Not only are metallic phases stiffer and stronger but they confer a far higher temperature capability to the final material. As such materials are notoriously difficult to process, we are now using several techniques involving pressure infiltration, electroless deposition and reactive wetting. We will discuss the success of these endeavors and the properties of the resulting ceramic/metallic compliant phase materials.
Supported by the Office of Science, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

The outstanding mechanical properties and high fracture resistance of shark tooth enameloid are the result of its intricate hierarchical arrangement of thin (50-80 nm) and long (>1 µm) crystallites of fluoroapatite Ca5(PO4)3F.[1] Compared to commercially available synthetic dental materials like amalgam, gold, and alumina ceramics, the application of fluoroapatite as tooth restoration material offers many advantages. Benefits of fluoroapatite include potential continuous remineralization at the surface, improved acid-resistance, and mechanical properties similar to those of human teeth which reduces the probability of failure at the interfaces. Additionally, there are many possibilities to tailor the geometry of synthetic crystallites of fluoroapatite for such applications.
Our aim is to create bioinspired tooth restoration materials, using shark tooth enameloid as a biological model. This bioinspired material exploits the advantages of fluoroapatite and is expected to provide similar properties in terms of load resistance and fracture toughness as observed in natural teeth. We have synthesized different crystal morphologies of fluoroapatite hydrothermally. By using various inorganic and organic additives, it was possible to tune the crystallite morphologies close to the natural tooth model. The most promising crystal geometries were selected to synthesize fluoroapatite/polymer-composites using methylmethacrylate (MMA) as a basic monomer in combination with crosslinkers like ethyleneglycoldimethacrylate (EGDMA). In order to improve the interactions between ionic fluoroapatite and neutral polymer, we added additional methacrylate monomers with polar substituents, for example methacrylic acid (GMAA).[2] To obtain a similar microstructure as found in shark tooth enameloid, ultracentrifugation was used to control the arrangement of the fluoroapatite crystals in a liquid monomer mixture before polymerization to polymethylmethacrylate (PMMA). An additional method used to structure our dental composites was the oriented growth of fluoroapatite rods on iron substrates by hydrothermal synthesis.[3]
The structural and mechanical characterization of the resulting synthetic bioinspired composites showed their great potential as dental materials with improved performance and durability.
[1] J. Enax, O. Prymak, D. Raabe, M. Epple, "Structure, composition, and mechanical properties of shark teeth", J. Struct. Biol. 178 (2012) 290-299.
[2] Evonik Industries, "Visiomer: Methacrylate monomers - Sales range", 2011.
[3] H. Chen, Z. Tang, J. Liu, K. Sun, S. R. Chang, M. C. Peters, J. F. Mansfield, A. Czajka-Jakubowska, B. H. Clarkson, "Acellular synthesis of a human enamel-like microstructure", Adv. Mater. 18 (2006) 1846-1851.

Complex organic/inorganic hybrid nanostructures found in biomaterials has been intensely investigated since these biocomposites were known to have superior mechanical properties than man-made composites, originated from its complex organized structures in micro- and nanoscale. Structural organization of most well-known biocomposites, such as nacre of abalone shell, can be described as horizontal stacking plates parallel to each other. Meanwhile, relatively little attention was given to biocomposites with a different structural motifs, the vertically alignment of nanostructures in composites. For instance, the armor of ancient fish and the teeth of Sea urchin are made of nanoparticles or nanofibrils vertically aligned against the top-most surface. In this presentation we demonstrate that engineering of nanocomposites with LBL assembly incorporated with ZnO nanowires can lead to the materials with seemingly “impossible” combinations of mechanical properties of high stiffness and high damping property, which has been known as contradiction to the knowledge of conventional composites. We examined the hierarchically structured nanocomposites with stacked nano-columns by nanoDMA investigating dynamic response of mechanical properties upon nanoindentation.

The Japanese pearl oyster (Pinctada fucata) n16 framework matrix protein is an integral part of the growth and formation of the mollusk shell biomineralization mechanism. It is a required component of the extracellular matrix with a dual mineralization role—as an anchor component to synchronize the assembly of the beta-chitin and N-series, Pif-series protein extracellular matrix for aragonite formation and as a regulator of aragonite formation itself. However, the mechanism by which this protein controls aragonite formation is not understood. Here, we investigate the mineralization potential and kinetics of the 30 AA N-terminal portion of the n16 protein, n16N. This sequence has been demonstrated to form either vaterite or aragonite depending upon conditions. Using in-situ potentiometric titration methods, we find that n16N is indeed responsible for the self-assembly characteristics found in vivo and in vitro, but is not involved with active Ca2+ binding or mineral nucleation processes. Based upon time- and peptide concentration - dependent sampling of mineral deposits that form in solution, we find that n16N is responsible for controlling where mineralization occurs in bulk solution. This protein sequence acts as a molecular spacer that organizes the mineralization space and promotes the formation of mineral constituents that contain ACC, vaterite, and aragonite. Without the concerted action of the n16N assemblages, unregulated calcite formation occurs exclusively. Thus, the n16 protein provides the regulation needed to have the characteristic polymorph, crystalline orientations and related mechanical properties associated to the microstructure of mollusk shells.

The Great East Japan Earthquake, which happened on March 11, 2011, made us aware once again that we had forgotten we were just one species within the great cycle of nature on earth, that we were allowed to survive only because of nature, and that the idea that we were somehow able to conquer the nature was simply an illusion.
Now, more than ever, is the time we must confront face-to-face the change from the underground resources type of civilization to one with a new way of life and technology that embraces a sense of nature. To do so, we must learn from nature that possesses the only sustainable society on earth and create technology which embraces such a view of nature.
We call technology, which cleverly revives nature&’s greatness, Nature Technology, and we have completed fundamental consideration of the micro-wind generator using mechanism of the dragonfly&’s wings, water free bath learning from bubbles, stain free surface learning from snail shell, electricity free air-conditioner and others.
We must now, in the midst of severe environmental restrictions, begin the great challenge of suspending and cutting back our escalating human activity, while living in a spiritually enriching way. How can we live in a spiritually fulfilling way on one planet? In order to find the form that this new way of life will take, we certainly need to adopt a backcasting point of view which starts with the prerequisite that we live on only one planet.

Photonic crystals (PC) with tunability in the visible or near-infrared region are of great significance in controlling light for display, sensor, “smart” medical dressings or telecommunication device. Functional materials play an essential role in the PC tunability, since these materials are able to switch photonic band gaps under external stimuli, such as magnetic field, temperature, mechanical force or pH. Therefore, stimuli-responsive materials engineered with hierarchical photonic structures are expected to present high performance. Unfortunately, hierarchical photonic structures with the combination of complex macro, meso and even nanoscales are still a challenge to model by using a conventional synthesis method. Herein, we address the problem by using biospecies as the template, and successfully fabricated ph-responsive and magneto-stimuli photonic crystal from Morpho butterfly wings. The optical properties in response to external stimuli were investigated. This work sets up a strategy for the design and fabrication of tunable photonic crystals with hierarchical structures for a wide potential use in many fields.

This presentation reports a modification approach for the controlled alternation of Morpho butterfly wing structures and the subsequent change of their optical properties. In nature, many biological species have amazing properties or skills that inspire humans for a long time. As a typical example, Morpho butterflies have attracted extensive attention due to the sophisticated 3D structures and unique optical properties of their colorful wings. Besides the substantial studies of their micro/nanostructures and optical properties, recent work has been focused on exploring new functionalities of the butterfly wings through the generation of structures templated by butterfly wings using different materials. For example, liquid based approach such as sol-gel chemistry has been used in the synthesis of structures of silicon oxide, aluminum oxide, titanium oxide, gold, silver, copper, etc that were templated from various butterfly wings. Those templated structures displayed good property enhancement in optical response, light harvesting, and catalytic properties. In this work, vapor based processes were investigated systematically in the modification of butterfly wings. Morpho butterfly wings were modified with both metallic and non-metallic materials with controlled thickness and spatial locations. The optical responses of the modified butterfly wings showed interesting trends with the change of the modification conditions. The findings provide opportunities in the generation of new bioinspired materials with improved properties and expanded functions. Coupled with well-established detection approach, these structures derived from the original butterfly wings also offer promises as key elements in the development of the next generation optical detection and chemical and biological sensing systems.

The merger of living microorganisms with classic material sciences results in responsive systems that exhibit desired functions on site. In order to build so called living materials, microorganisms are suspended in artificial habitats sandwiched between a supporting base layer made of acrylic lacquer and a porous cover layer that permit the exchange of gases, nutrients, and secondary metabolites and allow the organisms to grow in their confined spaces but are not enabled to leave it. [1]
In addition to the robust cyclic self-cleaning behavior [1], we created a self-sterilizing, antibacterial material that is capable to produce and release penicillin on site due to the incorporation of the penicillin-producing mold P. chrysogenum. [2]
Now, by utilizing algae as a new class of microorganisms and incorporating bioluminescent algae into the system, we expand the concept of living materials and generate a new functionality. Bioluminescence, commonly known from fireflies or the bioluminescent bay in Puerto Rico, is utilized in nature for vital functions ranging from defense to reproduction and has evolved more than 40 times. Here, we incorporate Pyrocystis lunula (dinoflagellates) into thin layers and mechanically actuate 20 individual pixel in order to generate pictures.
The incorporation of organisms, e.g. other fungi, algae, or bacteria into living materials uncovers aplenty of novel smart materials. Besides fanciful applications such as photosynthetic, self-cleaning high-rise buildings, living materials can be used as production units. By continuous nourishment of living materials, steadily formed secondary metabolites are delivered via a membrane into the environment. This provides a powerful production strategy, a convenient in-situ separation of product, and promises many application scenarios in material science and biotechnological production.
Literature:
[1] L.C. Gerber, F.M. Koehler, R.N. Grass, W.J. Stark, Incorporating microorganisms into polymer layers provides bio-inspired functional living materials, Proc. Natl. Acad. Sci. USA, 109(1), 90-94 (2012).
[2] L.C. Gerber, F.M. Koehler, R.N. Grass, W.J. Stark, Incorporation of penicillin-producing fungi into living materials to provide chemically active and antibiotic-releasing surfaces, Angew. Chem. Int. Ed., 51(45), 11293-11296 (2012).

Cephalopods are known as the chameleons of the sea - they can alter their skin&’s coloration, pattern, texture, and reflectivity to blend into the surrounding environment. Despite much research effort, there are few known strategies (natural or artificial) for emulating the unique reflectivity and coloration of cephalopods. Herein, we draw inspiration from a cephalopod structural protein known as reflectin to fabricate tunable biomimetic camouflage coatings. We demonstrate that the reflectance of these cephalopod-inspired films can be dynamically modulated between the visible and infrared regions of the electromagnetic spectrum in situ. Furthermore, we show that such coatings can make objects reappear and disappear when imaged with an infrared camera. In their totality, our studies represent a crucial step towards reconfigurable and disposable infrared camouflage for stealth applications.

Chiral nematic (CN) liquid crystalline ordering arises from the self-assembly of rod-shaped chiral mesogens into helical, twisting layers. When the spacing of these layers is on the order of the wavelengths of visible light, Bragg-like reflection occurs, resulting in brilliant iridescence. This structural coloration is the source of the striking visual appearance from many animals and plants, such as jewel beetles (from CN organization of chitin in the outer layer of their exoskeletons). Notably, the reflected light is circularly polarized, owing to the helical structure of the CN phase.
Cellulose nanocrystals are a renewable nanomaterial derived from acid hydrolysis of cellulose. Aqueous dispersions of cellulose nanocrystals can form lyotropic CN phases owing to their nanoscale rod-like morphology and inherent chirality. Inspired by the structural coloration of jewel beetles, our group at the University of British Columbia has utilized the CN phase of cellulose nanocrystals as a template for new materials prepared through evaporation induced self-assembly. These materials combine the structural coloration characteristic of CN phases with other desirable properties, such as responsive, tunable optical properties and high porosity. I will discuss our recent progress in preparing these materials for potential applications such as novel sensors and optical filters.

Biological organisms have developed a diverse range of light manipulation strategies to display intense coloration based on interference and diffraction phenomena in complex hierarchical material morphologies. These biological photonic architectures are often optimized according to criteria that are equally relevant in artificial optical systems, including color conspicuity, hue, brightness and the dynamic control thereof. Consequently, biomimetic and bio-inspired approaches for the creation of novel photonic systems could provide promising alternatives to traditional methods of developing optical technology. Here we present a recently developed photonic fiber material made from elastic components that was inspired by a hierarchical photonic structure found in the seeds of the tropical plant Margaritaria nobilis. The fibers reflection band can be tuned throughout the visible spectral range by applying mechanical strain. We present different fiber designs and discuss potential applications of this photonic material.

The usual interference theorem contradicts the property of single color reflection in different viewing angles. We explain the wide angle reflection property by exploring the nanostructures in the scales of the Morpho butterfly wings [1].
These optical active structures integrate three design principles leading to the wide angle reflection: alternative lamellae layers, Christmas tree like shape, and zigzag pattern of the ridges. In order to study their individual effects rigorously, we use 2D FEM simulation of the nanostructures of Morpho sulkowskyi [2] to calculate their reflection spectrum. The reflection spectrum is found to be broad (~ 90 nm) for alternating layers and can be controlled by varying the design pattern. The Christmas tree like pattern helps to reduce the directionality of the reflectance.
We fabricated exactly these structures by e-beam lithography. In contrast to the original butterfly structures they lay flat on the substrate with a height of 200 nm but mimic all important features of the original Morpho butterfly (Christmas tree like structure with alternating lamellae and offsets between the trees). It is found that our new samples maintain the intense blue characteristics with a wide angular range of reflection (± 25°). The experimental results are in agreement with the optical FEM simulations of the Morpho-type nanostructures. Our detailed analysis reveals that the intense blue color of the Morpho butterfly does not only depend on the irregular pattern of ridges [3] but also on the structural pattern of alternating lamellae layers with Christmas tree like shape. Consequently, these design principles can be used to produce surfaces with high irradiance in the future.
References:
[1] R. H. Siddique, S. Diewald, J. Leuthold, and H. Hölscher, "Theoretical and experimental analysis of the structural pattern responsible for the iridescence of Morpho butterflies," Optics Express 21, 14351-14361 (2013).
[2] R. A. Potyrailo, H. Ghiradella, A. Vertiatchikh, K. Dovidenko, J. R. Cournoyer, and E. Olson, "Morpho butterfly wing scales demonstrate highly selective vapour response," Nature Photonics 1, 123-128 (2007).
[3] S. Kinoshita, S. Yoshioka, and K. Kawagoe, "Mechanisms of structural colour in the Morpho butterfly: cooperation of regularity and irregularity in an iridescent scale," Proceedings of the Royal Society B: Biological Sciences 269, 1417-1421 (2002).

Large-scale replication of sophisticated 3D biomimetic nano- and microstructures faces difficulties even today. Here, we present a flexible replication process for optical active structures inspired by Morpho butterflies. This butterfly species shows a brilliant blue iridescence caused by “Christmas tree” like structures in their scales. These structures can be fabricated for example by e-beam lithography [1] but their cost effective, large-scale manufacturing is a challenge although various technical implementations have been shown [2].
To overcome this problem, we developed a unique combination of hot embossing and microthermoforming to shape the design and features in the nano-scale. The flexibility of our method allows the easy implementation of other non-optical features like super-hydrophobicity and self-cleaning as well.
First, we use hot embossing for the imprint of the nanostructures in a polymer foil. This embossing step is followed by micro-thermoforming, in which the foil is shaped on the micro-scale. We demonstrate a successful process combination with structure sizes several orders of magnitude smaller than conventional thermoforming. As a result, we introduce a method to create low cost biomimetic surfaces unrivalled by conventional large-scale techniques.
[1] Siddique, Diewald, Leuthold, Hölscher, Opt. Exp. 21, 14351 (2013)
[2] Sambles, Nature Photonics, 6, 141-142 (2012)

Intricate three-dimensional (3-D) bioorganic structures are assembled by a variety of living organisms to achieve impressive control of chemical, structural, and/or optical functions. For example, certain butterflies generate structurally-colored chitinous wing scales with 3-D microscale shapes and periodic meso-to-nanoscale features. While such hierarchical control of 3-D morphology under ambient conditions exceeds man-made capabilities, synthetic chemical approaches provide a rich palette of complex (multicomponent) inorganic chemistries that are biologically inaccessible to butterflies or other structure-forming organisms. In this work, the coupling of structurally-complex biogenic 3-D colored templates with chemically-complex synthetic inorganic materials has been examined for highly-tailorable optical performance. Specifically, a layer-by-layer (LbL) surface sol-gel (SSG) process has been utilized to apply thin, highly-conformal multicomponent oxide coatings onto Parides sesostris and Papilio blumei butterfly scales that, upon organic pyrolysis, were converted into freestanding doped titania structures with high-fidelity retention of the native scale morphologies. After carefully isolating intrinsic inter- and intra-butterfly color variations, controllable increases in the thickness of such high refractive index coatings were found to result in monotonic red-shifts in the color of as-coated scales and fired all-oxide replicas. In addition to tailoring structural color, titania replicas of P. blumei scales were converted into photoluminescent lanthanide-doped barium titanate (BT) replicas via a low-temperature microwave hydrothermal reaction process. This 3-D morphology-preserving conversion process can yield photoluminescent inorganic structures with an enormous variety of biogenic or bioinspired morphologies and tailorable colors (via doping of BT with one or more lanthanides) for unobtrusive, yet highly-distinct labeling of documents or goods for tracking or anti-counterfeiting purposes.

Epicuticular reflectors as color-producing structures have been found in the exoskeletons of different groups of beetles, such as tiger beetles [1], leaf beetles [2] and jewel beetles [3]. A multilayer structure model consisting of two types of layers with different refractive indices that are periodically stacked was used to describe these photonic structures and to predict their optical properties. In this study, we characterized the cuticular structures of the two ground beetle species Carabus auronitens and Carabus auratus both experimentally and theoretically. The results show that the primary origin of their colors is a multilayer structure formed by their inner epicuticle. In addition to the optical response generated by the “classical” multilayer structure, we found that modifications of the microstructure of layers situated at the interface between the incident medium and the epicuticle have a significant influence on the optical properties of the cuticle of both beetle species. The simulation results show that the thickness of the outermost layer of the multilayer structures formed by both beetle species is optimized to obtain the lowest reflectivity concurrent with the broadest reflection band width for the cuticle. However, the additional wax layer present on top of these outermost layers has a lower refractive index and increases the reflectivity, but this layer is essential for the beetles to prevent themselves from desiccation. Thus, the resulting coloration is a fine tuned compromise that meets the ecophysiological requirements of the animals. This principle of structural and compositional adjustments of two interfacial layers found in these biological photonic structures can provide insights for proper design of optical coatings for fine tuning of anti-reflection properties and band widths of optical devices.
References:
[1] Schultz, T. D. & Rankin, M. A. (1985). The Ultrastructure of the Epicuticular Interference Reflectors of Tiger Beetles (Cicindela). Journal of Experimental Biology, 117, 87-110.
[2] Kurachi, M., et al. (2002). The Origin of Extensive Colour Polymorphism in Plateumaris sericea (Chrysomelidae, Coleoptera). Naturwissenschaften, 89, 295-298.
[3] Hariyama, T., et al. (2005). The Origin of the Color of the Leaf Beetle, the Jewel Beetle, and the Damselfly and Their Intraspecific Communication. Zoological Science, 22, 1479-1479.

Nanoengineered surfaces offer new possibilities to enhance condensation heat transfer for various applications including thermal management, energy conversion, and water desalination. In nature, certain plants such as the Dogbane have superhydrophobic properties to alter the wetting behavior of condensed dew due to the design of the leaf nanostructures. Drawing from this inspiration, we developed superhydrophobic surfaces for enhanced condensation heat transfer. In particular, we have demonstrated two condensation modes, jumping-droplet and immersion condensation, with copper oxide nanostructures. In jumping-droplet-condensation, we were able to remove droplets at micrometric length scales (< 10 µm) via coalesced droplets that spontaneously jump off the surface due to the conversion of surface energy into kinetic energy. Accordingly, approximately 30% higher heat transfer coefficients compared to that on state-of-the-art dropwise condensing surfaces were experimentally demonstrated. In immersion condensation, we fabricated composite surfaces by infusing oil on heterogeneously-coated copper oxide surfaces, which allow droplets to nucleate immersed in the oil phase. This enabled not only easy droplet removal, but also low contact angles, and high nucleation densities. By achieving the three important attributes for enhanced condensation heat transfer, we demonstrated approximately 100% enhancement in heat transfer coefficients compared to that on dropwise condensing surfaces. These studies offer new surface designs to manipulate condensed droplets for heat transfer enhancement, and promises significant advances in next generation thermal and energy systems.

Superhydrophobic W₁₈ O₄₉ nanowire (NW) arrays were synthesized using a thermal evaporation and surface chemistry modification methods by self-assembled monolayer(SAM). As fabricated superhydrophobic W₁₈ O₄₉ NWs surface shows water contact angle of 163.2° and has reliable stability even in underwater conditions. Also the non-wetting W₁₈ O₄₉ NWs surface exhibits silvery surface by total reflection of water layer and air interlayer. This novel phenomenon is an obvious evidence of the Cassie-Baxter state of surface modified W₁₈ O₄₉ NWs arrays. The stability test of underwater superhydrophobicity of W₁₈ O₄₉ NWs arrays was conducted by changing hydrostatic pressure and surface energy of W₁₈ O₄₉ NWs arrays. The difference of water immersion depth of the superhydrophobic samples exhibited difference hydrostatic pressures. And alternating kinds of SAM resulted in the change of surface energy of the SAM-modified surfaces.The stability of superhydrophobicity in underwater conditions decreased exponentially as hydrostatic pressure applied to the substrates increased. In addition, as surface energy decreased, the underwater stability of superhydrophobic surface increased sharply. Specifically, superhydrophobic stability increased exponentially as surface energy of W₁₈ O₄₉ NWs arrays was decreased. Based on these results, the models for explaining tendencies of superhydrophobic stability underwater resulting from hydrostatic pressure and surface energy were designed. The combination of fugacity and Laplace pressure explained this exponential decay of stability according to hydrostatic pressure and surface energy. This study on fabrication and modeling of underwater stability of superhydrophobic W₁₈ O₄₉ NW arrays will help in designing highly stable superhydrophobic surfaces and broadening fields of superhydrophobic applications even submerged underwater.

Many state-of-the-art liquid-repellent materials are based on the lotus-effect, where a thin air layer is maintained throughout micro/nanotextures leading to high mobility of liquids. Such bioinspired structured materials, however, often lose their liquid repellency at moderate T < 90°C. Here, we demonstrate a class of lubricant-infused structured materials, inspired by the Nepenthes pitcher plant, that can maintain a robust omniphobic state even for low-surface-tension liquids at temperatures up to at least 200°C. We also demonstrate how liquid mobility on such surfaces can be tuned by a factor of 1000.

This presentation focuses on the heat and mass transfer between liquid droplets that are generated on bioinspired heat transfer surfaces. Thermal energy is the most abundant form of energy utilized in the industrialized world. Almost 90% of energy generated is either consumed or wasted thermally. Developing efficient approaches in the conversion, transportation, and storage of thermal energy is critical in meeting the sharply increased energy demand. Among many approaches developed, phase-change based heat transfer attracts extensive interest due to the minimum environmental impact and the massive existing installed base. In the phase-change based heat transfer process, efficient heat transfer is critically depending on the evaporation and condensation process. There have been various approaches developed in improving the efficiency of evaporation process. In the area of condensation, many investigations are focused on leveraging the unique heat transfer property in drop-wise condensation. During the drop-wise condensation process, liquid droplets, rather than liquid thin films, are formed on the solid surfaces to expose more areas for efficient heat transfer than in the case that forms liquid thin films. Those liquid droplets move and interact with each other on the solid surfaces during the condensation process. In this presentation, we will present the investigation of the heat/mass transfer during the interaction of such droplets on bioinspired surfaces. High speed camera, including both visible and IR imaging capabilities, were used to study the heat and mass transfer at microscale. Different modeling approaches were also explored to explain the findings. The results discussed will also be beneficial to other applications such as inkjet printing and spray process.

Unique properties of betaine polymers continue to be discovered regarding their non-fouling, blood compatibility, and biocompatibility. Our research aims at applying betaine polymers on medical devices to address unmet clinical needs. This report summarizes recent progress in developing betaine-modified contact lenses and drug-leaching devices.
Commercially available silicone hydrogel lenses were surface-modified using a one-step controlled polymerization process. Pre-clinical testing revealed that the surface wettability and lubricity of the contact lenses were significantly improved after surface modification. The advancing dynamic contact angle (DCA) of modified lenses was reduced by 71%. The DCA hysteresis is substantially lower than the 16 degree hysteresis on a commercial lens. The coefficient of friction (COF) of modified lenses was reduced by 62% relative to unmodified. The surface modification had no substantial effect on the bulk properties including water content, clarity, power, oxygen permeability, dimensions, and mechanical properties. The modification was stable in its wettability to an aggressive cleaning regimen with mechanical and oxidative challenges. Cleaning and Uptake studies with cleaner preservatives showed equal or better performance than the control lens. An initial comparative clinical study revealed no untoward clinical events after 4 to 6 hours of use by a population of adapted control contact lens wearers
Betaine monomers were applied to an orthopedic device (tibial nail, titanium alloy) and a leaching peripherally inserted central catheter (PICC). The surfaces of these devices were loaded with a model eluting agent (chlorhexidine or CHX) and modified with a betaine polymer. Polybetaine-modified orthopedic titanium samples were characterized for their surface chemistry and physical properties and found to have a homogenous surface modification. Through formulation optimization, controlled release of CHX was achieved for 8 weeks, as well as inhibition of the growth of both Gram-positive and Gram-negative organisms. Polybetaine-modified samples exhibited > 90% reduction in protein adherence relative to unmodified titanium substrates, indicating that the nonfouling properties are preserved throughout agent release. The polymeric modification system showed excellent mechanical integrity and strong adherence to the titanium substrate. Even after 4 weeks of CHX release in an aqueous solution at 37 °C, the shear strength of the polymer layers to the titanium substrate remained intact (> 10 MPa). A 4-log biofilm reduction was achieved on the modified external surface of a PICC shaft challenged with both gram positive and gram negative bacteria. Fibrinogen adsorption reduced 94 % compared with control catheter. The CHX can be released in a controlled profile by loading different amount of agent.

Evolution of antibiotics-resisting pathogens has become one of the greatest challenges in the battle of bacterial infection. Inspired by the structures of bacteria-invading viruses and antimicrobial peptides, we hypothesize that in addition to a balance of amphiphilicity and electronpositivity, the nanoscale architecture is another important factor that defines the efficiency of synthetic antimicrobial agents. Here we study the structure-activity relationship of a series of polymer brushes with well-defined structures that mimic spherical and rod-shaped viruses. Our preliminary data confirm polymer brushes exhibit much higher activity than individual polymer chains, suggesting the antimicrobial activity of small antimicrobial polymers can be improved and optimized by assembling them into different nanoscale architectures. We further show polymer brushes can be designed to have no appreciable hemolysis up to 500mu;g/mL, hence safe for human red blood cell, but high selectivity toward killing gram-positive and gram-negative bacteria. We attribute this enhanced activity and selectivity to the spatially-defined, multivalent interactions enabled by polymer brushes to remodel cell membranes, as revealed by synchrotron small angle x-ray scattering studies. Since not all bacteria are harmful, and infectious bacteria often coexist with blood cells, selectivity among different types of bacteria and blood cells as revealed in virus-mimicking polymer brushes is of great significance to the development of next generation antibiotics.

Common industrial metals, such as stainless steel, titanium, copper, and aluminum, are widely utilized in numerous industrial and medical applications, ranging from oil-transport pipelines, airplanes, to hypodermic needles and medical implants. However, many of the state-of-the-art surface coatings on these metals are still far from optimal: they create drag for fuel transport, nucleate ice on airplanes, and trigger fouling on marine vessels. Here, we report a simple, robust, and scalable manufacturing strategy to create omniphobic coatings onto common stainless steels, titanium, copper, and aluminum based on the concept of slippery liquid-infused porous surfaces (SLIPS) [1, 2]. The coatings can be applied onto different geometries, ranging from flat surface to the interior and exterior of tubes. Furthermore, our bioinspired coating is effective in repelling simple and complex fluids (e.g., blood), fluids of low-surface tensions such as pentane, as well as demonstrating anti-fouling and anti-corrosion characteristics. Detailed characterizations of the slippery coatings on metals will be reported in the meeting.
References
[1] Tak-Sing Wong, Sung Hoon Kang1, Sindy K. Y. Tang, Elizabeth J. Smythe, Benjamin D. Hatton, Alison Grinthal & Joanna Aizenberg, Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity. Nature 477, (2011).
[2] Tak-Sing Wong, Taolei Sun, Lin Feng, and Joanna Aizenberg, "Interfacial materials with special wettability', MRS Bulletin, vol. 38, pp.366 - 371 (2013).

In this work, short synthetic peptides are explored for the creation of a highly-interconnected dynamic electrically-active network. While peptides and proteins are an ideal natural system for achieving self-assembled structures, they are traditionally considered insulators, and are not well suited to electrical applications. However, by incorporating aromatic groups capable of stacking, and functional nanoformations such as carbon nanohorns, electrically active nanomaterials based on naturally occurring amino acids have been formed.
Microscopic and spectroscopic techniques have been used for the characterization of the peptides and their supramolecular structures. Here, short peptides featuring glycine (G), proline (P), and phenylalanine (F) have been investigated for use as a nanomaterial. The inclusion of P and G was expected to result in polyproline secondary structure, directing the interactions of the F residues which are capable of electron delocalization when stacked appropriately. Raman and Circular Dichroism (CD) spectroscopy were used to confirm the polyproline nature of the peptide backbone, while fluorescence and CD spectroscopy data supported aromatic stacking. Combined with basic computer modeling, the spectroscopic data were used to form a hypothetical model of the peptide self-assembly in water. Following this, self-assembly conditions were investigated in aqueous environments to create a network of nanofibers. Using atomic force microscopy (AFM) and electron microscopy (EM), the morphology of the nanofibers was investigated, largely concurring with our suggested model of aggregation. The conductivity of the network was investigated at a macroscopic scale using a two-probe system, showing a linear relationship between voltage and current. Conductivity properties were then acquired by multiple-probe scanning probe microscope (MPSPM) on the fiber network, uncovering quite different localized electrical properties. Based on the observed electrical and morphological properties, it is envisioned that the peptide nanofiber networks can be used for signal processing in neuromorphic applications.

Ancient DNA is preserved in spores, amber or fossils for over thousands to millions of years. The storage of DNA under favourable conditions results in extremely long stability, as evidenced by the reported recovery of viable bacteria from 250-million-year-old salt crystals.[1] Within these fossils a dense diffusion layer (polymerized terpenes or calcium carbonate) protects the sensitive nucleic acid molecule from harsh environmental conditions. This natural way of nucleic acid preservation inspired our encapsulation of DNA into glass particles.[2] In this room temperature molecular assembly, DNA is immobilized on the surface of cationic charged silica particles onto which a dense silica layer is deposited from sol-gel precursor. Co-interacting species is utilized to enable the compatibility of the sol-gel processes and DNA. Within the glass particles the DNA is hermetically sealed and protected against chemical attack and high temperatures. Investigations comparing directly stability between encapsulated DNA and free DNA showed that free DNA is completely destroyed by radical treatment, while encapsulated DNA is not affected at all. The DNA was recovered with the help of fluoride comprising solutions from the silica particle without harm analyzed by biochemical standard technique of real-time PCR and by Sanger-sequencing. The combination of protecting DNA against harsh environmental conditions by a non-toxic assembly and ultrasensitive biochemical analysis by qPCR thereby gives access to chemically stable tracers. The particles carry a unique barcode with a very low detection limit, which allows fingerprinting of consumer goods. Investigations of tagging commercial available polymers with our encapsulated DNA displayed how the encapsulates can be made compatible with commercial polymer technology, i.e. injection molding at 200°C. The identity of the polymers could be proven by qPCR with detection limits of 0.1 ppm, which shows the high potential of the new material for anti-counterfeiting and identifying labeled objects.
[1] R. H. Vreeland, W. D. Rosenzweig, D. W. Powers, Nature 2000, 407, 897-900
[2] D. Paunescu, R. Fuhrer, R. N. Grass, Angew. Chem. Int. Ed. 2013, 52, 4269 -4272

Galectins are receiving increased interest as therapeutic targets due to their emerging role in diverse physiological and pathological processes, including angiogenesis, tumor immune evasion, inflammation, and viral infection. Current approaches to inhibit galectin activity at the protein level are based on di- or polysaccharides related to the galectin-binding ligand β-lactose, which typically have low galectin-binding affinity and often short metabolic half-lives in vivo. Here, we created polypeptide β-sheet nanofibers bearing the galectin binding disaccharide n-acetyllactosamine (LacNAc) to mimic the polyvalent display of LacNAc residues that capture galectins within native extracellular matrices, and characterized their efficacy as galectin-1 inhibitors. In particular, we prepared a β-sheet fibrillizing polypeptide domain, QQKFQFQFEQQ (Q11), terminated with an n-acetylglucosamine (GlcNAc) residue that self-assembled into high aspect ratio nanofibers under aqueous conditions. GlcNAc residues were efficiently converted to LacNAc in the presence of β1,4-galatosyltransferase and a galactose sugar donor, without perturbing nanofiber morphology. LacNAc-displaying nanofibers bound galectin-1 with higher affinity than soluble β-lactose, likely because of their polyvalent nature and the reduced entropy of the nanofiber-bound disaccharide. This binding interaction was specific, since galectin-1 binding to LacNAc nanofibers was inhibited by high concentrations of soluble β-lactose. Additionally, galectin-1 bound weakly to GlcNAc nanofibers, which was expected based on the known low affinity of soluble GlcNAc for galectin-1. Varying the molar ratio of GlcNAcQ11 to Q11 in the nanofibers provided a facile route to fine tune LacNAc polyvalency and, in turn, nanofiber affinity for galectin-1, which is challenging to achieve with synthetic polysaccharides. Galectin-1 induces apoptosis of Jurkat T cells, a model for CD4+ T lymphocytes, and LacNAc nanofibers inhibited Jurkat apoptosis in the presence of galectin-1. Taken together, these results demonstrated that glycosylated polypeptide nanofibers provide polyvalent, high-affinity ligands for galectin-1, and suggest their potential as potent inhibitors of galectin bioactivity for cancer, anti-viral, or auto-immunity therapeutics.

In vertebrates, red blood cells (RBCs) are the workhorses of respiration, tasked with delivering oxygen throughout the diverse tissues in the body. They constitute roughly 45% of the total volume of whole blood and show extremely long circulation times (~120 days). Consequently, they have been investigated as both a platform and an inspiration for artificial delivery systems. Moreover, the characteristic discoid shape gives rise to the majority of RBCs remarkable mechanical and transport properties. As such, the materials science community has begun to develop routes to generate RBC mimics using a variety of particle synthesis techniques. Using synthetic polymers and hydrogels may improve the durability of RBC mimics over natural RBCs which are extremely sensitive to even minor environmental perturbations.
As an alternative approach, we have begun to explore the use of vertebrate RBCs as feedstock for shape-preserving transformations into composites and inorganic materials. Building upon our recent work of silica cell replication (PNAS, 109:17336-17341), we show that silica stabilization allows complete preservation of RBC shapes following drying and high temperature processing (650 C). For composite cells (Si-RBCs), we are investigating a number of interesting features. First, both normal (discocyte) and abnormal (echinocyte) morphologies can be captured and used to generate Si-RBCs, providing a simple means of shape control over composite particles. Second, Si-RBCs readily assemble surface lipid bilayers such as those derived from RBCs themselves (ghosts). Finally, we observe that the iron heme centers (~10^9 / cell) in Si-RBCs retain catalytic (peroxidase) activity and that particles can be engineered to allow dispersal in aqueous and organic solvents. These exciting properties of Si-RBCs provide new avenues to explore a diverse range of applications such as shape preserving transformations into functional materials (e.g, SiO2 to Si), “cloaked” delivery systems, and heterogeneous biocatalysis using a renewable and highly scalable synthetic strategy.

The photosynthetic complex I (PSI) is one of the most important proteins in photosynthesis, able to efficiently harvest solar Sun energy and transfers it into exited electrons. High energy electrons are created at primary donor P700 at the bottom of this protein complex and then flow in a well-known transport pathway through the protein scaffold via built in electron acceptor molecules and iron-sulphur clusters. The light illumination-triggered activation of charge separation in PSI complexes induces formation of PSI dipoles on solid surface. The directions of the formed dipoles are defined by PSI geometrical orientations. Due to the bulky structure of the protein, it is not easy to achieve a well-defined orientation during self-assembling, which is crucial for applications and characterisation. The present work is dealing with the effect of light on the tunnelling current through a single PSI complex employing Conducting Atomic Force Microscopy (CAFM). Measured electrical properties of PSI at light conditions can be used to better understand geometrical orientation of the protein and related electrical properties of PSI. Such photoactive biological materials can find application as light-sensing elements in bio-inspired electronics.

Structural color offers promise for a new class of colorants derived from a single platform of approved materials. The ultimate goal of such a platform would be threefold: 1. Large-scale production of dispersible particles with mechanical robustness, 2. Demonstrated ability to produce colors covering the entire visible spectrum and 3. Elimination of multiple regulatory obstacles associated with the introduction of new dyes and pigments. We present a bio-inspired structural color platform that affords easy tuning of various physical structure parameters on the scale of wavelengths in the visible range. Gram-scale yields have been realized from parent solutions with <1% solid content using a simple, economical, and scalable method. Color is adjustable and controllable by doping photonic structures with low amounts metal nanoparticles. Plasmonic resonances are achieved and enhanced by photonic resonances without compromising the highly regular porosity of our photonic crystals. The relevant lengthscales for photonic engineering are orders of magnitude larger than for plasmonic engineering (~100-1000 nm vs. ~10 nm, respectively). This allows for independent systematic study of each element&’s effect on the overall color. Further, liquid infiltration of and interaction with the porous structures can be controlled by surface chemistry treatments facilitating easy dispersion into binding resins in paint-like embodiments. Beyond color applications, controlled liquid infiltration and regular porosity facilitates easy access to the metal nanoparticles for applications pertinent to their inherent properties (e.g. catalysis, microbial resistance), creating a new type of functional colorant.

Avian feather coloration has long been studied as an example of structural color in vertebrates, as bird feathers display brilliant coloration through pigmentation and the formation of submicron structures. In certain species of birds, non-iridescent coloration is associated with the feather barb, which contains a medullary layer of spongy β-keratin. This medullary region reflects vibrant colors through self-organized nanoscale structures containing voids giving a high refractive index contrast between the β-keratin and air. Chicken β-keratin is a highly abundant biomolecule produced by the ton each year by the poultry industry, and represents a cheap, abundant raw material that is produced on an industrial scale. However, chicken β-keratin does not self-organize into submicron features to produce color in vivo. Here we demonstrate conditions by which thin films of chicken β-keratin can be induced to form nanoscale structures that scatter light, leading to the production of structural color. Additionally, biomimetic approaches based on accessory pigments in the feather barb have been used to enhance color scattered from the chicken β-keratin thin films. Therefore, this work represents a first step in the generation of low-cost, easy-to-manufacture colored films that can be applied to practical devices, such as sensors and color displays.

Several strategies have been explored from viewpoint of biomimetics to accomplish artificial photosynthesis by using synthetic macromolecules as a medium such as liposomes, supramolecules, and hydrogels. Differing from disordered solution systems in which multiple components such as photosensitizer and catalytic nanoparticle are diffusively mixed, the photochemical reactions occur efficiently in medium due to maintenance of the dipersibility of the components and specific molecular arrangement. Here we attempt to clarify the effect of medium hierarchy for photoinduced electronic transmission among multiple components. By immobilizing each component on tubulin and integrating them via self-assembly to microtubules, ideal component arrangements with optimum distance for the electronic transmission will be possible.
In this study as the first step, we designed and fabricated Ru(bpy)32+-immobilized microtubules for photoinduced H2 generation. By immobilizing Ru(bpy)32+ on microtubules, the structure enables to avoid aggregation among the Ru(bpy)32+ that cause loss of photoenergy in self-quenching process. The hierarchy of tubulin/microtubules is controlled by using 6-thioguanosine-5&’-triphosphate (6-thio-GTP) which maintains the structure as tubulin, or guanosine-5&’-(β,γ-methylene)triphosphate (GpCpp) which maintains the structure as microtubules, respectively. When the immobilized Ru(bpy)32+ is excited by photoenergy, it will effectively give electron to Pt nanoparticle through viologen and H2 generates.

Increasing number of nanotech-based products and nanomaterials manufacturing industries are responsible for releasing toxic chemical to the environment and cause adverse health risk to people.1, 2 The design and development of functional adsorbents are needed for removal of toxic nanoparticles (NPs) from environment.3-6 A viable and cost-effective material was developed for removal of gold nanoparticles from aqueous solution using apple peel. The surface of the peel was chemically modified, characterized with SEM, FTIR and the adsorption efficiency for gold nanoparticles was analyzed spectrophotometrically. The analytical parameters and kinetics of the adsorption process were calculated and methods for the regeneration of adsorbent were developed. The results reveal that the functionalized peel has good adsorption capacity and selectivity.

Background: Anatomically and physiologically accurate in vitro bench-top models of the heart are critical for rapid and effective cardiac device design. During the contraction phase of the cardiac cycle the apex of the left ventricle rotates anti-clockwise (viewed from apex) while the base of the heart has a net clockwise rotation. The resultant complex motion is left ventricular (LV) twist. Cardiac wall motion in the majority of bench-top simulators is achieved through the use of a pulsatile pump to passively drive flow in an elastomeric model but most do not simulate LV twist. An ideal bench-top cardiac simulator would mimic the soft material properties and active contractile motion of the native heart tissue and be capable of replicating physiological and pathological motions.
Method: A finite element method (FEM) approach was proposed for simulating biologically-inspired arrangements of myocardial fiber-like contractile elements in soft elastomeric matrices using ABAQUS software. We first validated the modeling approach in 2D and then demonstrated a 3D simulation that can generate similar twisting motions to that of the heart. Based on this simulation, we fabricated a soft cardiac simulator with active pneumatic air muscles (PAMs) cast in silicone (Ecoflex ,Smooth-On Inc.) with a multi-step molding process. Rotation of the LV was measured with electromagnetic trackers (3D Guidance TrakSTAR). Subsequently, pathological motion was simulated by deactivating contractile elements in the FEM and physical model in order to represent the clinical scenario of a transmural infarct in which muscles are rendered non-contractile or akinetic.
Results: The FEM model predicts horizontal and vertical strain with an accuracy of 84% and 87% for single and multiple actuator test specimens respectively. The 3D FEM model predicts an apical rotation of 7.78°±0.55° with LV supported at the base, with experimental measurements agreeing closely at 7.89°±0.59°.These values are within clinical values of 6.8°±2.5° as reported in the literature [1]. A key feature of the approach is the ability to selectively deactivate active elements in both the simulation and our experimental model. Apical rotation decreased predictably as PAMs were sequentially de-activated.
Conclusion: We have demonstrated a finite element method approach that predicts physiological motion for a fully soft structure with embedded contractile elements. We have also fabricated a physical model whose motion matches simulation results and clinical data with applications as an in vitro bench-top cardiac simulator for meaningful device evaluation. Furthermore, we have demonstrated the ability to generate pathological-like motion with simulations and experiments by sequentially de-activating selected PAMs - a key feature not present in other silicone models. Using this simulation, an increased understanding of akinetic motion can be achieved.
[1] E. Nagel et al, European heart journal 2000, 21, 582-9

Fibronectin is a large, multimodular glycoprotein of the extracellular matrix, which is assembled by cells into a fibrillar meshwork. However, the self-association properties within the individual fibronectin molecules allow fibrillogenesis to occur in a variety of cell-free systems. Here, we present transmission electron microscopy studies of fibronectin fibers formed as the adsorbed fibronectin monolayer is pulled from the air-liquid interface. These fibers are 1-2 mu;m in diameter and can be up to 1 cm in length. Visualization of their internal architecture by electron microscopy gives insight to the processes that mediate such a drastic shape transition from a two dimensional monolayer to a dense fibrillar structure. Our results support a mechanism whereby the combination of the external force applied and the ensuing buffer drainage causes monolayer invaginations, which eventually come together to form bilayers, arranged into characteristic spiral patterns, stabilized primarily through electrostatic interactions. Such an organization, rather than driven by thermodynamic equilibrium, represents kinetically trapped states. One consequence of this internal fiber organization is a large surface area, which can be readily accessible to nanoparticles smaller than 10 nm. Moreover, the elastic properties of the individual fibronectin molecules within the fibers render them highly elastic: they can be extended up to six times their testing length before breakage. In summary, based on the self-association properties of a naturally occurring biomolecule, we were able to generate highly extensible fibers, with a large surface to volume ratio. Such fibers can be used as a model system to study certain aspects of the biology of cell-derived fibronectin fibers. Moreover, their dynamic self-assembly represents an example of how regular patterns can be formed from amphiphilic polymers that self-associate to form insoluble monolayers at the at/liquid interface and they exhibit sufficient cohesion to withstand monolayer dissolution upon pulling and at the same time are flexible enough to accommodate the necessary deformations required for assembly into a fibrillar structure.

The rise of nanomedicine in the recent years has provided new types of polymeric drug delivery nanosystems and scaffolds for tissue regeneration activities. In this talk, versatile nanotechnology enabled approaches to advance the cardiovascular stents will be presented. Biodegradable polymeric scaffolds that mimick the extracellular matrix were developed exhibiting fiber diameters of 800-1000nm. Biodegradable nanoparticles loaded with anti-inflammatory and anti-oxidant drugs were synthesized and embedded in the scaffolds to achieve the dual role of drug delivery and regeneration of endothelium. Drug release kinetics, physicochemical and structural characterization of the nanoparticulate scaffolds, cytoxicity and cell viability studies follow to test the effectiveness of the engineered matrices in relation with their toxicology profile. Such scaffold may serve as drug eluting nanoplatform to be deposited onto stent surface in order to overcome the delayed endothelialization of drug eluting stents.
Acknowledgments: This work has been financially supported by the NanoCardio Project funded from GSRT Greece and the European Commision.

Superhydrophobic surfaces with water repellent and water adhesive properties have received much attention in both academia and industry. However, most of the demonstrated superhydrophobic surfaces exhibited either one of the water-repellent or water-adhesive characteristic. The reversible switching of superhydrophobic adhesion properties within a same substrate, which requires elaborate regulation of surface roughness or surface energy, is greatly desired to demonstrate advanced lab-on-a-chip platforms for biological or chemical detection where minimal liquid-substrate interaction is required.
Here, we describe a novel and facile method to obtain superhydrophobic surface with switchable and controllable water adhesive property using gas-driven morphological changes of palladium (Pd) coated Si nanowire arrays. By regulating the gas-ambient between atmosphere and hydrogen, the superhydrophobic adhesion property of Pd coated Si NW arrays was repeatedly switched between water-repellent and water-adhesive. The reversible changes in the water-adhesive properties was almost instant (< 5 seconds), which could be achievable through quick morphological phase transitions of the coated Pd layer on the Si nanowires induced by the adsorption and desorption of hydrogen atoms during the alternating ambient. We also highlight some of the newer and emerging lab-on-a-chip applications using this water adhesion controllable surface including cell culture, hydrogel formation, and biological analysis.

Self-assembly is a process in which interacting bodies are autonomously driven into ordered structures. Static structures such as crystals often form through simple energy minimization, while dynamic ones require continuous energy input to grow and to sustain. Dynamic systems are ubiquitous in nature and biology, but have been proven to be challenging to understand and engineer. Here we bridge the gap from static to dynamic self-assembly by introducing a model system based on ferrofluid droplets on superhydrophobic surfaces. The droplets self-assemble under a static external magnetic field into simple patterns that can be switched to complicated dynamic dissipative structures by applying a time-varying magnetic field. The transition between the static and dynamic patterns involves kinetic trapping and shows complexity that can be directly visualized.
Jaakko V. I. Timonen, Mika Latikka, Ludwik Leibler, Robin H. A. Ras, Olli Ikkala, Science (2013) accepted.

Simple routes to form complex shapes are of fundamental interest, but also have practical ramifications in field such as optics and catalysis. Recently, we demonstrated how complex hierarchical microstructures could be made by simple sequential modulations of reaction conditions such as the pH, temperature and CO2 concentration in a beaker containing standard chemicals. The shape of the structures is dictated by the local chemical gradients at the growth fronts of the developing structures. We therefore developed a range of microfluidic devices that allow continues interactive manipulation of these localized environmental conditions. The direct in-situ visualization, the stabilization of the growth conditions by the continuous influx of fresh growth medium, and the dynamic control over the influx of all the reactants allows us to further elucidate the underlying mechanism, and to synthesis micro-structures with unprecedented precision and complexity in the both material composition and shape.

Materials that maintain function and structure under fouling conditions are of significant interest for applications in industrial and biomedical contexts. The ability to maintain the surface properties after exposure to various liquid or biological contaminants is essential to ensure reliable and robust functionality. In this work, a new series of photocurable omniphobic fluorogels have been developed for the target of anti-fouling and multi-functionality. These fluorogels, even in the form of a flat film, exhibit broad liquid repellency, chemical resistance and anti-biofouling properties. They also show tunable transparency and elasticity, as well as the potential for coating, photolithography, molding and replication on arbitrary surfaces. Unique interfacial properties are considered to contribute to the broad anti-fouling properties of the fluorogels.

Swimming is dynamically a part of the hydrodynamic field and can be considered as a field of the optimal control motion. Animals move by instinct according to the situation which they are confronting with. Therefore, their instinctive motion is optimal most of the time. The movement of animals can be classified roughly into two kinds: the fast motion with the maximum speed and the motion with the minimum energy consumption. Considering the foreleg of the soft shelled turtle as a flat plane, several sets of movement of the foreleg were observed and calculated theoretically. The theoretical results agreed the obsevation results in the both cases with the maximum speed and the minimum energy consumption. Applying the theoretical movement of the soft shelled turtle foreleg to human movement in swimming, the general S-shaped pull stroke is the minimum energy consumption motion in free-style. It became clear that there was a different stroke for generating the maximum speed in free-style. That was the soft shelled turtle style of fast swimming, the I-shaped pull strokes. In 2002 when I announced this theory, there was only one fast swimmer whoes free-style swimming strokes coincidentary accorded with the I-shaped pull with fewer number of strokes at that time.He was the Olympic gold medalist Ian Thorp. Now the I-shaped stoke has become main stream in free style.
This I -shaped pull stroke is applicable to all 4 stlyles of swimming. By the appearance of the high-speed swimsuit, the world records were left very unnatural and technology-oriented. However, the high-tech swimsuit is no longer accepted. The improvement of swimming technique has revived to be an important mean to update records. This time, I explain the new style of swimming and forecast the time when the new world record is updated after the swimsuit regulation revision.

Due to their adverse role in bacterial pathogenicity, the study of biofilms has mostly focused on their prevention, dispersion and removal. However, this has led to an overlooked opportunity to develop biofilms as functional materials. Biofilms provide advantages such as surface attachment and higher resilience to environmental stresses compared to planktonic bacteria, making them highly attractive for materials applications. Unique to biofilms is a high surface-area extracellular matrix that surrounds the bacteria, which contains amyloid-like fibers that can be manipulated using traditional molecular biology techniques. We utilize peptide display using our recently developed Biofilm-Integrated Nanofiber Display (BIND) platform to covalently immobilize and display two orthogonal protein fusions - a reporter fluorescent protein and an enzyme - on the curli fiber matrix of E. coli biofilms. We show that the proteins can be captured onto the fibers selectively from a complex mixture and that they remain functional once attached to the biofilm. Furthermore, we demonstrate that the biofilms protect the proteins from denaturation in adverse conditions, such as exposure to organic solvents. All steps in the process, from scaffold expression to protein capture, can be genetically programmed and controlled. We envision this highly modular system to have widespread applications in materials requiring proteins displayed in a site-specific and controllable manner, such as biosensing, biocatalysis and wastewater purification.

Directed protein assembly is a commonplace phenomenon in nature and is frequently responsible for the development of natural biomaterials and biominerals. For example, matrix protein self-assembly plays a significant role in the growth and organization of the mineral in hard tissues. One of the ultimate goals in the area of biomineralization is to develop highly stable biomimetic polymers to mimic the functions of matrix proteins for controlling mineral formation.
Peptoids, or poly-N-substituted glycines, are a novel class of non-natural polymers developed to mimic both structures and functionalities of polypeptides, and bridge the gap between biopolymers and bulk polymers. As with peptides, sequence-specific peptoids can be efficiently and cheaply synthesized by using automated solid-phase synthesis. Moreover, peptoids exhibit much higher protease and thermal stabilities than polypeptides. Recently, we successfully demonstrated that peptoids were able to mimic soluble matrix proteins for dramatic controls over both CaCO₃ crystal morphology and growth kinetics, and some peptoids exhibited an unprecedented 23-fold acceleration of crystal growth at nanomolar concentration range.
In this presentation, we report our progress in the directed assembly of peptoids for controlling CaCO₃ mineralization, exploiting peptoids to mimic the assembling function of matrix proteins and exploiting the assembled peptoid-based biomimetic films to mimic the function of extracellular matrix protein films. Specifically, on freshly-cleaved mica surfaces, acidic peptoids composed of alternating polar and nonpolar residues were able to self-assemble into biomimetic films comprising hexagonally-patterned nanofibers in the presence of Ca2+ ions. Both ex situ and in situ AFM studies showed that peptoid- Ca2+ complexes first formed discrete nanoparticles on mica surfaces, and then these kinetically-trapped intermediates gradually transformed into stable peptoid nanofibers with hexagonal orientations. We found that although the increased solution ionic strength was able to slow down peptoid fiber formation, higher salt concentration drove controllable multilayered upright assembly of peptoid nanofibers. Mechanistic studies by AFM-based dynamic force spectroscopy (DFS) indicate that competition between peptoid-mica (PM) and peptoid-fiber (PF) interactions is critical for forming biomimetic films. The binding free energies extracted from DFS studies show that peptoid-Ca2+ complexes bind much more strongly to freshly-cleaved mica surfaces than to pre-assembled peptoid fibers. Mica-directed peptoid assembly is highly sequence-specific; a slight change in the chemistry of nonpolar residues results in a dramatic change in peptoid assembly. CaCO₃ mineralization results demonstrate that peptoid-based biomimetic films are able to direct the formation of CaCO₃ crystals with their orientations parallel to the original peptoid fibers.

A detailed understanding of how interactions between living cells contribute to function and disease in natural environments requires defined and biologically relevant in vitro models for assessing the behavior of small cellular ensembles. Here, we describe a three-dimensional (3D) microscopic printing strategy that enables multiple populations of eukaryotic and prokaryotic cells to be organized within essentially any 3D geometry, including adjacent, nested, and free-floating groups. In this approach, a focused femtosecond laser beam is scanned across the face of a digital micromirror device, which serves as a dynamic-masking element to direct multiphoton fabrication of microscopic containers around selected cells suspended in thermally set gelatin. After excess reagent is removed, trapped cells are localized within sealed cavities formed by covalently crosslinked gelatin, a highly porous material that is readily permeable to biologically active species, including nutrients, cellular waste products, antibiotics, and quorum-sensing signals. As a consequence, cells confined within gelatin microcontainers cells can undergo division, in some cases to extremely high densities, and engage in chemically mediated behaviors with adjacent confined populations. We demonstrate application of this micro-3D printing technology to the study a range of cellular behaviors, including synergistic interactions between nested bacterial populations, adversarial relationships between bacteria and macrophages, and invasion of physically restricted spaces by cancer cells.

Inspired by the endoparasitic worm, Pomphorhynchus laevis, which swells its proboscis and attaches to the intestinal wall of its host, we have developed a new tissue adhesive based on shape-changeable, water-responsive microneedles that mechanically interlocks with tissue in wet environments. Each cone-shaped needle is made of a stiff non-swellable core and a tip that is rigid in its dry state, but swells upon contact with water. The worm-inspired microneedles are able to effectively penetrate tissue with little force, as well as maintain continuous, seamless contact with tissue, and high adhesion strength by interlocking with tissue through localized swelling of the microneedle tips. The unique design allows the needles to stick to soft tissue with minimal damage to the tissue, yet strong fixation of the microneedle adhesive is maintained even while attached to dynamic tissues during multiple bending cycles. When the microneedle adhesive is used during skin grafts fixation, the adhesion strength due to the swollen tips of the microneedle is more than three times stronger than conventional surgical staples. Interestingly, upon removal from tissue, the microneedle adhesive causes less trauma to tissue, compared to staples. Since the water-responsiveness of the swellable tips is reversible, drugs, such as antibiotics and anti-inflammatories, can easily be loaded into the tips during swelling and the swollen tips can return to the original shape and stiffness after drying to aid insertion. Thus, the microneedle adhesive can administer multiple types of agents directly into the wound microenvironment in a minimally invasive manner. Uniquely, this bio-inspired design provides rapid universal soft tissue adhesion with minimal damage, less traumatic removal, reduced risk of infection and and potential for delivery of bioactive therapeutics.

Shape specific interactions such as the streptavidin-biotin interactions have been studied and ubiquitously employed for biotechnological applications. Hydrophobic collapse of amphiphilic β-hairpin peptides (e.g. MAX1 VKVKVKVKVDPPTKVKVKVKV-NH2) into fibrils and their hierarchical assembly into branched, hydrogel networks has been extensively studied. A physically crosslinked hydrogel network is formed due to fibrillar entanglement and branched defects in hydrophobic collapse during fibril formation. Alternating valine residues with side chains of the same size are responsible for the hydrophobic collapse of the molecule into a β-hairpin and fibril nanostructure with branching. In this work, we demonstrate introduction of shape specific hydrophobic interactions via design of new peptide LNK1. In, LNK1 (Nal)K(Nal)KAKAKVDPPTKAKAK(Nal)K(Nal)-NH2) the non-beta turn valines were replaced with Napthylalanine and alanine amino acid residues, with hydrophobic side chains of larger and smaller volume, respectively, than valine. Thus, formation of a ‘lock and key&’ type structure was attempted in the hydrophobic core of the peptide fibrils that would eliminate fibril branching. Similarly another pair of sequences,
WDG1:V(O)(Nva)(O)(hF)(O)(Nva)(O)V(O)V(dP)PT(O)V(O)(Nva)(O)(hF)(O)(Nva)(O)V-amide)
TRG1:hF(O)(Nva)(O)(V)(O)(Nva)(O)(hF)(O)V(dP)PT(O)(hF)(O)(Nva)(O)(V)(O)(Nva)(O)(hF)-amide)
which when folded into hairpins resemble a wedge and trough shape respectively, also demonstrate such hydrophobic specificity which is responsible for elimination of branching in fibrils formed from a equimolar blend of these two peptides. The folding properties of these peptides and their influence on network mechanical properties have been studied by Circular Dichroism spectroscopy (CD), Transmission Electron Microscopy (TEM) and Oscillatory Rheology.

Precisely defined multi-dimensional hierarchical structures in nano- or micrometer scale are a requisite for the fabrication of various functional devices in all fields of science and engineering. Conventional lithography techniques (i.e., photolithography, e-beam lithography, dip-pen nanolithography, nanoimprint lithography, and etc.) have been utilized to fabricate various devices for electronics, mechanics, and biomedical engineering. Despite their remarkable attributes and capabilities, those fabrication processes often require complicate procedures as well as considerable labors and expenses. However, in nature many hierarchically organized nanostructures (i.e., diatoms, abalone shell, butterfly wing, and moth eyes) possess exquisite structures and functions, which surpassing the capability achievable by current top-down and bottom-up fabrication methods. Moreover, many of these structures are made of a simple basic building block, helical nanofiber (i.e., collagen for animals and cellulose for plants) through self-templated assembly processes.
Inspired by nature&’s self-templated assembly processes, herein, we developed a novel biomimetic micropatterning technique to create well-defined two- and three-dimensional hierarchical structures by controlling surface tension force of helical nanofiber particles at the air/liquid/solid interfaces. We utilized M13 bacteriophage (phage) as a model helical nanofiber building block, due to its&’ monodispersity, liquid crystalline property, and genetic flexibility to display functional peptides. By controlling meniscus forces, we could induce formation of the smectic nanofilament phases of the phage and tune the adhesion properties between the nanofilaments-to-nanofilament and nanofilament-to-solid substrates. The resulting structures possess hierarchically organized two- and three-dimensional periodic structures with exquisite optical properties. These self-assembled multi-dimensional hierarchical structures were tunable by varying parameters that affect the kinetics and thermodynamics of assembly such as pulling speed, pulling time, surface charges of phages, and ionic concentration. The resulting microstructures could enhance the power of phage-based piezoelectric energy generations. Our facile bio-inspired self-assembly strategy may provide the way to fabricate large-scale advanced micro electronic or optical devices and biomedical applications in the future.