Antithrombogenic Properties of Amphiphilic Block Copolymer Coatings: Evaluation of Hemocompatibility Using Whole Blood.

Antithrombogenicity is one of the most critical properties required for materials used in biomedical devices, particularly in devices that contact blood. The antithrombogenicity of surfaces coated with amphiphilic block copolymers composed of hydrophobic poly(2-methoxyethyl acrylate) (M) and hydrophilic poly(,-dimethylacrylamide) (D) segments was investigated using plasma protein and whole blood with regard to protein adsorption, thrombus formation, platelet activation, and clotting kinetics. Three types of block copolymers and a random copolymer were synthesized using one-pot reversible addition-fragmentation chain-transfer (RAFT) polymerization under conditions of high yield and high molecular weight.

Clay-supported novel bimetallic core-shell Co-Pt and Ni-Pt nanocrystals with high catalytic activities.

We demonstrate the striking potential of exfoliated clay (synthetic hectorite; Laponite XLG) platelets to prepare bimetallic (Co-Pt and Ni-Pt) NCs with well-defined structures. Catalytic studies show a strong bimetallic synergistic effect of the core-shell NCs; their catalytic activities are much higher than those of monometallic NCs and other bimetallic core-shell NCs.

Highly protein-resistant coatings and suspension cell culture thereon from amphiphilic block copolymers prepared by RAFT polymerization.

Novel amphiphilic block copolymers composed of hydrophobic (poly(2-methoxyethyl acrylate): M) and hydrophilic (poly(N,N-dimethylacrylamide): D) segments were synthesized by living radical polymerization: a reversible addition-fragmentation chain-transfer polymerization. Two types of amphiphilic block copolymers, triblock (MDM) and 4-arm block ((MD)4) copolymers with specific compositions (D/M = (750-1500)/250), were prepared by a versatile one-pot synthesis. These copolymers show good adhesion to various types of substrates (e.

Novel bimetallic core-shell nanocrystal-clay composites with superior catalytic activities.

Clay (synthetic hectorite; Laponite XLG) plays a very crucial role in the formation and stabilization of core-shell nanocrystals and affords high stability, large BET surface area and stimulates the exceptional catalytic activity of the core-shell NCs.

Controlled synthesis and tunable properties of ultrathin silica nanotubes through spontaneous polycondensation on polyamine fibrils.

This paper describes a facile approach to a biomimetic rapid fabrication of ultrathin silica nanotubes with a highly uniform diameter of 10 nm and inner hollow of around 3 nm. The synthesis is carried out through a spontaneous polycondensation of alkoxysilane on polyamine crystalline fibrils that were conveniently produced from the neutralization of a solution of protonated linear polyethyleneimine (LPEI-H(+)) by alkali compounds. A simple mixing the fibrils with alkoxysilane in aqueous solution allowed for the rapid formation of silica to produce LPEI@silica hybrid nanotubes.

Preparation and characterization of highly planar flexible silver crystal belts.

We report a novel simple one-pot strategy for fabricating pure and highly planar silver (Ag) crystal belts. Unique single-crystal Ag belts (high width-to-thickness ratio ~50) were successfully synthesized in high yield (80 wt%) by reducing AgNO3 using N,N,N',N'-tetramethylethylenediamine (TEMED) as a reducing and a structure-determining agent in the presence of polyethylene glycol (PEG) under mild conditions.

Superior CO catalytic oxidation on novel Pt/clay nanocomposites.

Nanostructured novel Pt/Clay nanocomposites consisting of well-defined Pt nanoparticles prepared by clay-mediated in situ reduction displays very high thermal stability, large BET surface area and superior catalytic activity for CO oxidation as compared to a model reference Pt/SiO2 catalysts. CO oxidation has attracted renewed attention because of its technological importance in the area of pollution control. The Pt/Clay system consisting of Pt nanoparticles strongly immobilized between the atomic layers of clay inhibits nanoparticle sintering and loss of catalytic activity even after prolonged heating at high temperatures.

Bioinspired synthesis of a soft-nanofilament-based coating consisting of polysilsesquioxanes/polyamine and its divergent surface control.

The synthesis of polysilsesquioxanes coating with controllable one-dimensional nanostructure on substrates remains a major long-term challenge by conventional solution-phase method. The hydrolytic polycondensation of organosilanes in solution normally produces a mixture of incomplete cages, ladderlike, and network structures, resulting in the poor control of the formation of specific nanostructure. This paper describes a simple aqueous process to synthesize nanofilament-based coatings of polysilsesquioxanes possessing various organo-functional groups (for example, thiol, methyl, phenyl, vinyl, and epoxy).

Synthesis of highly active and thermally stable nanostructured Pt/clay materials by clay-mediated in situ reduction.

Novel and intriguing one-pot in situ method for the preparation of nanostructured Pt-clay materials under simple conditions is reported. In this synthesis, an inorganic clay mineral such as synthetic hectorite ("Laponite XLG") or natural montmorillonite ("Kunipia F") serves as a mild and effective reducing agent for Pt ions, which is uncommon for such a clay system, and also acts as an outstanding stabilizer for the resulting Pt nanoparticles. In aqueous solution, exfoliated colloidal clay platelets forms complex with Pt ions in the initial stage of mixing.

Proliferation and harvest of human mesenchymal stem cells using new thermoresponsive nanocomposite gels.

For tissue engineering and regenerative medicine, stem cells should be effectively cultured in vitro. New thermoresponsive nanocomposite gels (MD-NC gels), consisting of inorganic clay (hectorite) and copolymers composed of hydrophobic 2-methoxyethyl acrylate (MEA) and hydrophilic N,N-dimethylacrylamide (DMAA) units, could be applied in cell culture and cell harvesting without trypsinization, specifically using mesenchymal stem cells (MSCs). The composition of the MD-NC gel (the ratio of the two monomer types and the clay content) was found to determine its swelling properties in the culture medium, thermosensitivity, protein adsorption, and cell attachment and proliferation.

Approaches to nanostructure control and functionalizations of polymer@silica hybrid nanograss generated by biomimetic silica mineralization on a self-assembled polyamine layer.

We report the rational control of the nanostructure and surface morphology of a polyamine@silica nanoribbon-based hybrid nanograss film, which was generated by performing a biomimetic silica mineralization reaction on a nanostructured linear polyethyleneimine (LPEI) layer preorganized on the inner wall of a glass tube. We found that the film thickness, size and density of the nanoribbons and the aggregation/orientation of the nanoribbons in the film were facile to tune by simple adjustment of the biomimetic silicification conditions and LPEI self-assembly on the substrate. Our LPEI-mediated nanograss process allows the facile and programmable generation of a wide range of nanostructures and surface morphologies without the need for complex molecular design or tedious techniques.

Development of soft nanocomposite materials and their applications in cell culture and tissue engineering.

Novel soft nanocomposite materials with unique organic/inorganic network structures have been developed by extending the strategy of "organic/inorganic nanocomposites" to the field of soft materials. The structures described here were synthesized by in-situ free-radical polymerization of various monomers in the presence of exfoliated clay (hectorite) in aqueous media. The nanocomposite hydrogels (NC gels) and soft nanocomposites (M-NCs) obtained were flexible and transparent soft materials, regardless of the clay content, that could be prepared in various shapes and surface forms, each consisting of individually different polymer/clay network structures.

Self-healing in nanocomposite hydrogels.

Polymer hydrogels with characteristics distinct from those of solid materials are one of the most promising candidates for smart materials. Here, we report that a nanocomposite hydrogel (NC gel) consisting of a unique polymer/clay network structure, can exhibit complete self-healing through autonomic reconstruction of crosslinks across a damaged interface. Mechanical damage in NC gels can be repaired without the use of a healing agent, and even sections of NC gels separated by cutting, from whichever the same or different kinds of NC gel, perfectly (re-)combine by just contacting the cut surfaces together at mildly elevated temperatures.

Direct generation of silica nanowire-based thin film on various substrates with tunable surface nanostructure and extreme repellency toward complex liquids.

We report our new achievement on the direct generation of linear polyethylenimine@silica hybrid and silica thin films on various substrates, which is composed of 10 nm nanowire silica structure with tunable micro/nano hierarchical surface morphology. We found that a process for the rapid and controlled self-assembly of crystalline template layer of linear polyethylenimine on substrate surface is critical for the formation of ultrathin silica nanowire structure and micro/nano hierarchical morphology, since the template linear polyethylenimine layer directly promotes the hydrolytic condensation of alkoxysilanes. Templated silica mineralization on the self-assembled linear polyethylenimine layer was confirmed by the studies of X-ray photoelectron spectroscopy (XPS) and thin film X-ray diffraction (XRD).

Molecular Characteristics of Poly(N-isopropylacrylamide) Separated from Nanocomposite Gels by Removal of Clay from the Polymer/Clay Network.

The extraordinary mechanical and swelling/deswelling properties of nanocomposite (NC) gels are attributed to their unique organic (polymer)/inorganic (clay) network structure. In this study, poly(N-isopropylacrylamide) (PNIPA) was successfully separated from an NC gel network by decomposing the clay (hectorite) using hydrofluoric acid (HF). A very low HF concentration (0.

Controlled formation of polyamine crystalline layers on glass surfaces and successive fabrication of hierarchically structured silica thin films.

The formation of silica films on the glass plate whose surface was precoated by crystalline linear poly(ethylenimine) (LPEI) in advance was systematically investigated via controlling the surface-specific crystallization of the LPEI on the glass plate. Immersing glass substrates into a hot aqueous solution of LPEI containing additives such as transition metal ions and acidic compounds and retaining them on 30 °C for desired periods resulted in the formation of crystalline LPEI layers on the substrates. Subsequently dipping this LPEI-coated glass into silica source solutions afforded successfully hierarchically structured silica film which coated continuously the surface of the substrates.

Successful transplantation of in vitro expanded human corneal endothelial precursors to corneal endothelial surface using a nanocomposite sheets.

Background: Though the transplantation of in vitro expanded human corneal endothelial precursors in animal models of endothelial damage by injecting into the anterior chamber has been reported, the practical difficulties of accomplishing such procedure in human patients have been a hurdle to clinical translation. Here we report the successful transplantation of in vitro expanded human corneal precursor cells to an animal eye using a transparent Nano-composite sheet and their engraftment.

Materials & Methods: Human Corneal endothelial cells (HCEC) were isolated from human cadaver eyes with informed consent and expanded in the lab using a sphere forming assay in a novel Thermoreversible Gelation Polymer (TGP) for 26 days.

Thermoresponsible cell adhesion/detachment on transparent nanocomposite films consisting of poly(2-methoxyethyl acrylate) and clay.

Soft, transparent and mechanically tough nanocomposite (M-NC) films composed of poly(2-methoxyethyl acrylate) (PMEA) and inorganic clay (hectorite) were studied as substrates for a living cell harvest system. It was found that five cell types could all be cultivated to confluence on the surface of M-NC n films with clay content (n = 10-23 wt%), although the cells hardly cultivated on the surface of chemically-cross-linked PMEA and linear PMEA films. Further, it was found that the cells cultured on the surfaces of M-NC films can be detached, without any enzymatic digestion, by decreasing the medium temperature and/or simultaneously using gentle pipetting.

Vacuum membrane distillation by microchip with temperature gradient.

A multilayered microchip (25 x 95 mm) used for vacuum distillation is designed, fabricated and tested by rectification of a water-methanol mixture. The polymer chip employs a cooling channel to generate a temperature gradient along a distillation channel below, which is separated into a channel (72 microm deep) for liquid phase and a channel (72 microm deep) for vapor phase by an incorporated microporous poly(tetrafluoroethylene) (PTFE) membrane. The temperature gradient is controlled by adjusting hotplate temperature and flow rate of cooling water to make the temperatures in the stripping section higher than the increasing boiling points of the water-enriched liquids and the temperatures in the rectifying section lower than the decreasing dew points of the methanol-enriched vapors.

Palladium nanoparticles captured in microporous polymers: a tailor-made catalyst for heterogeneous carbon cross-coupling reactions.

A new strategy based on polymerization-induced phase separation (PIPS) techniques was proposed for fabricating palladium nanoparticles (PdNPs) captured in a microporous network polymer. Pd(OAc)(2) was premixed with a monomer having a poly(amidoamine)-based dendrimer ligand, and subsequently this was thermally polymerized with an excess amount of ethylene glycol dimethacrylate under PIPS conditions. In this system, the formation of PdNPs occurred concurrently with the polymer synthesis in a one-pot process, even with no additional reducing reagent.

Bioinspired synthesis of continuous titania coat with tunable nanofiber-based network structure on linear polyethylenimine-covered substrates.

We report using the substrates covered with self-organized linear polyethylenimine (PEI) layer as biomimetic template to direct the formation of high-quality titania coat with well-defined nanofiber-based network structure. The titania deposition was simply achieved by dipping the PEI substrates into aqueous solution of titanium bislactate under ambient conditions. We found that crystalline PEI layer on the substrates is important for achieving titania coat with nanofiber-based structure.

Water motion and movement without sticking, weight loss and cross-contaminant in superhydrophobic glass tube.

We report that a simple fabrication of a superhydrophobic nanosurface consisted of a grass-like silica thin film on the inner wall of a glass tube and its feature in water motion and water movement. The glass tube with a superhydrophobic inner wall can make the water flow with friction-drag reduction and completely preventing water sticking. Transferring water by this tube did not cause weight loss at all.

Vacuum membrane distillation on a microfluidic chip.

A multilayered microfluidic chip used for vacuum membrane distillation is designed, fabricated and tested by rectification of a water-methanol mixture.