Rapid development in the area of low-temperature fuel cells has led to increased attention on catalyst synthesis with cost effective and environmentally-benign technology (green chemistry). In this study, a highly dispersed palladium nanoparticle catalyst was successfully prepared on a bacterial cell support by a single-step, room-temperature microbial method without dispersing agents. The metal ion reducing bacterium Shewanella oneidensis were able to reduce palladium ions into insoluble palladium at room temperature when formate was provided as the electron donor. The prepared biomass-supported palladium nanoparticles were characterized for their catalytic activity as anodes in polymer electric membrane fuel cell for power production. The maximum power generation of the biomass-supported palladium catalyst was up to 90% of that of a commercial palladium catalyst.

We present recent developments in rolled-up helical nanobelts in which helical structures are fabricated by the self-scrolling technique. Nanorobotic manipulation results show that these structures are highly flexible and mechanically stable. Inspired by the helical-shaped flagella of motile bacteria, such as E. coli, artificial bacterial flagella (ABFs) are a new type of swimming microrobot. Experimental investigation shows that the motion, force, and torque generated by an ABF can be precisely controlled using a low-strength, rotating magnetic field. These miniaturized helical swimming microrobots can be used as magnetically driven wireless manipulators for manipulation of microobjects in fluid and for target drug delivery.

RNA- and DNA-mediation or templating of materials has been used to synthesize nanometer scale wires, and CdS nanoparticles. However, RNA and DNA have the potential to act as catalysts, which could be valuable tools in the search for new routes to materials synthesis. RNA has the ability to catalyze splicing and cutting of other RNA molecules. Catalytic activity has been extended to more general classes of reactions for both RNA and DNA using in vitro selection methods. However, catalytic activity in materials synthesis is a more recent idea that has not yet found great application. The first example of RNA-mediated evolutionary materials synthesis is discussed with specific data examples that show incompatibility of reagents in the solvent system utilized. The hydrophobic reagent Pd2(DBA)3, used as a metal precursor, was observed to spontaneously form nanostructures composed of Pd2(DBA)3 or Pd(DBA)3 rather than palladium nanoparticles, as originally reported 1. A case study of this materials synthesis example is described including the complimentary use of multi-length scale techniques including transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning TEM (STEM), electron energy loss spectroscopy (EELS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and optical microscopy (OM). This example raises important questions regarding the extent to which non-aqueous solvents should be used in nucleic acid-mediated processes, the nature of selections in enzyme and materials development, and the requirement for chemical compatibility of the precursor molecules. The importance of good characterization tools at every stage of an in vitro selection is illustrated with concrete examples given. In order to look at the way forward for nucleic acid-mediated materials synthesis, an examination of the chemical interaction of nucleic acids with various precursors is considered. Application of density functional theory calculations provides one means to predict reactivity and compatibility. The repertoire of chemical interactions in the nucleic acids is considered vis-à-vis common metals and metal chalcogenides. The case is made for the need for water-soluble syntheses and well-controlled kinetics in order to achieve the control that is theoretically possible using nucleic-acids as a synthetic tool.

A novel material design was developed by functionalizing a biocompatible hydrogel material with organic boundary lubricants. Polyvinyl alcohol was functionalized with varying molar ratios of 0.2, 0.5, and 1.0 moles of lauroyl chloride. Tribological and mechanical characterization was performed by means of nanofriction testing and nanoindentation to determine the influence of the hydrocarbon chains on the friction coefficient and elastic modulus of the hydrogels. It was found that fusing of the lubricant to the polymer material has a positive effect on the surface friction properties, yet an unfavorable effect on stiffness properties of the gel due to the processing method.

Recently, more studies have been conducted in chemical and biological applications using microfluidic or nanofluidic devices.1 Polymer-based materials have been newly developed in this field due to the great needs of easy processing, cost-effectiveness and clarity for the material. However, it is still challenging to control of the surface properties of these devices on demand. Especially, for biological analysis or detection, micro-fluidics should handle aqueous samples but, most of the current materials in use for micro-fluidic devices are relatively hydrophobic (such as PDMS, PMMA and cyclo-olefin-co polymer, etc). Therefore, they usually need an extra assistance rather than a capillary force to flow the aqueous samples. In this paper, we utilized layer-by-layer deposition of polymer to modify the surface of the micro-channel of the device in order to control surface properties of the micro-channel. We have been studied polyelectrolyte multilayer(PEM) coatings to control surface wettability of the open structures and found various hydrophilic films. Here we demonstrate polyelectrolyte multilayer film as an effective coating for inner surface of micro-fluidic devices to lowering the water contact angle, so that the aqueous fluid will travel smoothly with the channels. Compared to the other surface treatment method such as base cleaning or plasma irradiation, the PEM coating exhibit highly sustained water wettability. Polyelectrolytes used for this study are weak polyelectrolytes including biodegradable polymer such as poly(hyaluronic acid) (HA) for future biological applications.

Organic/inorganic hybrids of silicon and their subsequent chemical modification are of interest for tailoring and structuring surfaces on the nanoscale. The formation of monolayers on hydroxylated silicon surfaces was employed to synthesize molecular dimethylsiloxane chains by wet-chemical condensation reactions, using dimethylmonochlorosilane as the precursor. The SiH group of the resulting dimethylsilyl termination could be selectively oxidized to the SiOH group, which opened the possibility of bonding another species. By repeating the condensation and oxidation cycle the stepwise growth of one-dimensional dimethylsiloxane chains was achieved. The ongoing chain growth was characterized by attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), and determination of the surface energy by contact-angle experiments.

State-of-the-art tissue engineering strategies increasingly rely on the performance of bioactive hydrogels formed via cell-friendly crosslinking reactions. Enzymatic reactions possess ideal characteristics for such applications, but they are currently still underexplored in biomaterials design. Here we report the development of hybrid bioactive hydrogels formed via a posttranslational modification reaction using phosphopantetheinyl transferase (PPTase). PPTase was shown to catalyze the covalent crosslinking of CoenzymeA-functionalized poly(ethylene glycol) (PEG) multiarm macromers and recombinantly produced acyl carrier protein (ACP) dimers. Crosslinking kinetics and physicochemical properties of PPTase hydrogels were characterized. Proof-of-principle experiments demonstrate the successful covalent bio-functionalization of gels with a CoA-derivatized cell adhesion peptide. Polymerization of gels in the presence of primary mammalian cells was shown to result in no loss in cell viability compared to a well established, chemically crosslinked gel system.

Herein we present methods for synthesizing monodisperse mesoporous silica particles and silica particles with bimodal porosity by templating with surfactant micelle and microemulsion phases. The fabrication of monodisperse mesoporous silica particles is based on the formation of well-defined equally sized emulsion droplets using a microfluidic approach. The droplets contain the silica precursor/surfactant solution and are suspended in hexadecane as the continuous oil phase. The solvent is then expelled from the droplets, leading to concentration and micellization of the surfactant. At the same time, the silica solidifies around the surfactant structures, forming equally sized mesoporous particles. We show that hierarchically bimodal porous structures can be obtained by templating silica microparticles with a specially designed surfactant micelle/microemulsion mixture. Oil, water, and surfactant liquid mixtures exhibit very complex phase behavior. Depending on the conditions, such mixtures give rise to highly organized structures. A proper selection of the type and concentration of surfactants determines the structuring at the nanoscale level. Tuning the phase state by adjusting the surfactant composition and concentration allows for the controlled design of a system where microemulsion droplets coexist with smaller surfactant micellar structures. The microemulsion droplet and micellar dimensions determine the two types of pore sizes.

SU8 Negative photoresist is finding high demand in applications such as MEMS sensors and waveguides. The possibility of photolithographic patterning and high physical and dielectric properties are attracting ever more users among workers in the electronics industry and increasingly in biomedical applications. In our work we employ an original method of exposing of SU8 and create high aspect ratio structures on glass and other substrates. Dry plasma etching results of negative epoxy-based photoresist by Inductively Coupled Plasma system using gases O2 and CF4 are presented.

Numerical simulations were performed to see the effect of geometrical misalignment in pressure driven flows. Geometric misalignment effects on flow characteristics arising in three types of interconnection methods a) end-to-end interconnection, b) channel overlap when chips are stacked on top of each other, and c) the misalignment occurring due to the offset between the external tubing and the reservoir were investigated. For the case of end-to-end interconnection, the effect of misalignment was investigated for 0, 13, 50, 58, and 75% reduction in the available flow area at the location of geometrical misalignment. In the interconnection through channel overlap, various possible misalignment configurations were simulated by maintaining the same amount of misalignment (75% flow area reduction) for all the configurations. The effect of misalignment in a Tube-in-Reservoir interconnection was investigated by positioning the tube at an offset of 164μm from the reservoir center. All the results were evaluated in terms of the equivalent length of a straight pipe. The effect of reynolds number (Re) was also taken into account by performing additional simulations of aforementioned cases at reynolds numbers ranging from 0.075 to 75. The results are interpreted in terms of equivalent length (Le) as a function of Re and misalignment area ratio (A1:A2), where A1 is the original cross-sectional area of the channel and A2 is the available flow area at mismatch location. Equivalent length calculations revealed that the effect of misalignment in tube-in-reservoir interconnection method was the most insignificant when compared to the other two methods of interconnection

The covalent immobilization of crude lipases within silica-based macroporous frameworks have been performed by combining sol-gel process, concentrated direct emulsion, lyotropic mesophase and post-synthesis functionalizations. The as-synthesized open cell hybrid monoliths exhibit high macroscopic porosity, around 90 %, providing interconnected scaffold while reducing the diffusion low kinetic issue. The entrapment of enzymes in such foams deals with a high stability over esterification and transesterification batch process catalysis.

Capillary liquid flows have shown their ability to generate micro and nano-structures which can be used to synthesize material in the micro or nanometric size range. For instance, electrified capillary liquid jets issued from a Taylor are broadly used to spin micro and nanofibers when the liquid consists of a polymer solution or melt, a process termed electrospinning. In this process, the electrified capillary jet may develop a nonaxisymmetric instability, usually referred to as whipping instability, which very efficiently transforms electric energy into stretching energy, thus leading to the formation of extremely thin polymer fibers. Even though non axysimmetric instabilities of electrified jets were first investigated some decades ago, the existing theoretical models provide a qualitative understanding of the phenomenon but none of them is accurate enough when compared with experimental results. This whipping instability usually manifests itself as fast and violent lateral motion of the charged jet, which makes it difficult its characterization in the laboratory. However, this instability also develops when electrospinning is performed within a liquid bath instead of air. Although it is essentially the same phenomenon, the frequency of the whipping oscillations is much slower in the former case than in the latter, thus allowing detailed experimental characterization of the whipping instability. Furthermore, since the outer fluid is a liquid, its density and viscosity may now be used to influence the dynamics of the electrified capillary jet. In this work we present and rationalize the experimental data collecting the influence of the main parameters on the whipping characteristics of the electrified jet (frequency, amplitude, etc.).

Metastable vaterite crystals were produced by increasing the pH of Ca2+- and CO3 2--containing solutions through diffusing ammonia gas. The SEM and TEM studies indicate that this ammonia-induced vaterite is polycrystalline with a 6-fold symmetry of the crystal aggregate. The morphology and crystallographic properties of this assemblage change druing crystallization. One hour after nucleation starts, vaterite grains display a spherical structure composed of nano-particles (5-10 nm) with random crystallographic orientations. After that, horizontal layers begin to develop at the edge of the sphere and gradually tilt toward the center as they grow vertically, which results in a three-dimensional morphology with a dent in the center. The vaterite grains mature fully 16 hours after nucleation. TEM analysis indicates the grown vaterite grain (50-60 μm) consists of numerous hexagonal pieces of single crystals (1-2 μm) of similar crystallographic orientations. High-resolution TEM demonstrates that these single crystals grow along (001) with {110} hexagonal boundaries.

Self-assembly is a promising technique to overcome fundamental limitations with integrating, packaging, and generally handling individual electronic-related components with characteristic lengths significantly smaller than 1 mm. Here we briefly summarize the use of capillary and magnetic forces to realize two example microscale systems. In the first example, we use capillary forces from a low melting point solder alloy to integrate 500 μm square, 100 μm thick silicon chips with thermally and chemically sensitive metal-polymer hinge actuators, for potential medical applications. The second example demonstrates a path towards self-assembling 3-D silicon circuits formed out of 280 μm sized building blocks, utilizing both capillary forces from a low melting point solder alloy and magnetic forces from integrated, permanent magnets. In the latter example, the utilization of magnetic forces combined with capillary forces improved the assembly yield to 7.8% over 0.1% achieved previously with capillary forces alone.

Numerical computations and order-of-magnitude estimates are used to analyze a jet of a very viscous liquid of finite electrical conductivity that is injected at a constant flow rate in an immiscible dielectric liquid under the action of an electric field. The conditions under which the injected liquid can form an elongated meniscus with a thin jet issuing from its apex (a cone-jet) are investigated by computing the flow, the electric field, and the transport of electric charge in the meniscus and a leading region of the jet. The boundaries of the domain of operation of the cone-jet mode are discussed. The current transfer region determining the electric current carried by the jet is analyzed taking into account the viscous drag of the dielectric liquid surrounding the jet. Conditions under which the electric current/flow rate characteristic follows a square root law or departs from it are discussed.

Carbon nanotube (CNT)-nickel/nickel oxide (Ni/NiO) core/shell nanoparticles (CNC) heterostructures were prepared in a unique single-step synthetic route by direct chemical precipitation of nanoparticles on CNT surface. Chemical vapor deposition (CVD)-grown CNTs (average diameter ˜42.7±12.3 nm) allowed for direct nucleation and uniform coating of Ni/NiO core/shell nanoparticles (average diameter ˜11.8±1.7 nm). The crystal structure, morphology, and phases in CNC heterostructures were studied using high resolution transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Subsequently, the as-produced CNC heterostructures were incorporated into polyvinyl alcohol (PVA) hydrogel resulting in CNC heterostructure-PVA hydrogel with ˜ 75% water absorbing capability. These novel hydrogels were also characterized by SEM and showed actuation under 0.2 T magnet. They are promising for smart analytical devices and platform.

Dynamic Interactive Systems are defined by networks of continuously exchanging and reversibly reorganizing connected objects (supermolecules, polymers, biomolecules, pores, nanoplatforms, surfaces, liposomes, cells). They are operating under the natural selection to allow spatial / temporal and structural / functional adaptability in response to internal constitutionalor to stimulant external factors. In this minireview we will disscuss some selected examples of organic/inorganic SYSTEMS MATERIALS, covering a) the sol-gel resolution of constitutional architectures from Dynamic combinatorial libraries and b) the generation of Dynamic Hybrid Materials and SYSTEMS MEMBRANES able to evolve insidepore architectures via ionic stimuli so as to improve membrane transport functions.

A regular hexagonally packed biomimetic moth-eye antireflective surface acts as a diffraction grating at short wavelengths of the visible spectrum and shallow angles of incidence. These gratings display strong backscattered iridescence with 6-fold optical symmetry. The optical symmetry of real moth eyes is effectively infinite as nature utilizes large number of uniquely orientated domains. In this work we report on a biomimetic moth-eye surface created via nanosphere lithography with a very large distribution of close-packed tessellated domains and the resulting optical symmetry is compared to that of another widely known highly isotropic diffraction grating, also inspired by nature, the sunflower pattern. A white-light laser reflectometry system is used to measure and compare the diffraction pattern isotropy from both structures. The tessellated close-packed structure diffraction pattern approaches that of infinite optical symmetry even though the underlying pattern only possesses a six-fold symmetry. Hence, the angular isotropy observed for the sunflower pattern is replicated to a large extent via a self-assembly procedure, whilst circumventing the complicated design and manufacturing requirements of the sunflower pattern.

The dynamic mechanical behaviour of a series of cyclic olefin copolymers (COCs) with varying norbornene content has been examined in the vicinity of the glass transition temperature, Tg. The temperature of the transition has been shown to increase linearly with increase in norbornene content. Measurements of both the elastic storage modulus, E′, and loss modulus, E″, have decreased exponentially with rise in temperature above Tg . A levelling-off in E″ occurred at >20 °C above Tg for all copolymers. The results of Dynamic Mechanical Thermal Analysis (DMTA) have been used in the identification of optimum conditions for hot embossing. At >20 °C above Tg in a region of viscous liquid flow, the hot embossing of COC has resulted in a full replication of channel depth without cracking or distortion.

Traditional neural cultures are formed from disassociating primary neurons that are sourced from animals. However by disassociating them, any larger organizational structure between the neurons is lost. In an effort to regain some of the lost organization a device that is capable of recreating and monitoring a unidirectional connection between two populations is proposed. Initial validation toward a fully functional device is presented. Using soft lithography techniques, a microfluidic chip has been designed and produced with a design conducive for facilitating such a neuron culture. Using a specialized adhesive method, this chip can be attached and removed from a commercially available microelectrode array. Finally, cell viability is demonstrated using the PC12 neuron-like cell line after exploring several device configurations. Further efforts will be focused on primary neuron culture and establishment of a unidirectional network.