Synthesis of novel chitosan/sodium hyaluronate/iridium hydrogel nanocomposite for wound healing application.

A novel chitosan/sodium hyaluronate/iridium (CHI/SH/Ir) hydrogel nanocomposite with a unique microstructure containing vertically aligned pores is fabricated via an electrophoresis technique. The formation of orderly vertical pores in CHI/SH/Ir hydrogel nanocomposite is due to the confinement of hydrogen bubbles produced from the water electrolysis during electrophoresis that limits their lateral movement and coalescence. In a wet state, the diameter for the vertical pores is 600-700 μm.

Atomistic insights into migration mechanism of graphene-based membranes on soil mineral phases.

Graphene-based membranes (GBM) will migrate in the soil and enter the groundwater system or plant roots, which will eventually pose potential risks to human beings. The migration mechanism of GBM depends on the interface behavior of complex soil components. Herein, we use molecular dynamics (MD) simulations to probe the interface behavior between GBM and three type minerals (quartz, calcite and kaolinite).

Fabrication of Cu Micromembrane as a Flexible Electrode.

A Cu micromembrane is successfully fabricated and validated as a porous flexible electrode. The Cu micromembrane is prepared by functionalizing individual polypropylene (PP) fibers in a polypropylene micromembrane (PPMM) using a mixture of polydopamine (PDA) and polyethyleneimine (PEI). The mixture of PDA and PEI provides adhesive, wetting, and reducing functionalities that facilitate subsequent Ag activation and Cu electroless plating.

Bubble-Channeling Electrophoresis of Honeycomb-Like Chitosan Composites.

A chitosan composite with a vertical array of pore channels is fabricated via an electrophoretic deposition (EPD) technique. The composite consists of chitosan and polyethylene glycol, as well as nanoparticles of silver oxide and silver. The formation of hydrogen bubbles during EPD renders a localized increase of hydroxyl ions that engenders the precipitation of chitosan.

A flexible IrO membrane for pH sensing.

An optimized mixture of polydopamine (PDA) and polyvinyl alcohol (PVA) is employed as the surface functionalizing agent and reducing agent to encapsulate individual polypropylene (PP) fibers of polypropylene micromembrane (PPMM). The functionalized PPMM becomes hydrophilic to allow the formation of Au nuclei for subsequent electroless Au deposition. The metalized PPMM is further deposited with IrO nanoparticles, and evaluated as a flexible and porous pH sensor.

Flexible Optogenetic Transducer Device for Remote Neuron Modulation Using Highly Upconversion-Efficient Dendrite-Like Gold Inverse Opaline Structure.

A remote optogenetic device for analyzing freely moving animals has attracted extensive attention in optogenetic engineering. In particular, for peripheral nerve regions, a flexible device is needed to endure the continuous bending movements of these areas. Here, a remote optogenetic optical transducer device made from a gold inverse opaline skeleton grown with a dendrite-like gold nanostructure (D-GIOF) and chemically grafted with upconversion nanoparticles (UCNPs) is developed.

Highly Ordered Polymer Nanostructures via Solvent On-Film Annealing for Surface-Enhanced Raman Scattering.

Surface-enhanced Raman scattering (SERS) has been a useful sensing technique, in which inelastic light scattering can be significantly enhanced by absorbing molecules onto rough metal surfaces or nanoparticles. Although many methods have been developed to prepare SERS substrates, it is still highly desirable and challenging to design SERS substrates, especially with highly ordered and controlled three-dimensional (3D) structures. In this work, we develop novel SERS substrates with regular volcano-shaped polymer structures using the versatile solvent on-film annealing method.

Self-healable and anti-freezing ion conducting hydrogel-based artificial bioelectronic tongue sensing toward astringent and bitter tastes.

Numerous efforts have been attempted to mimic human tongue since years. However, they still have limitations because of damages, temperature effects, detection ranges etc. Herein, a self-healable hydrogel-based artificial bioelectronic tongue (E-tongue) containing mucin as a secreted protein, sodium chloride as an ion transporting electrolyte, and chitosan/poly(acrylamide-co-acrylic acid) as the main 3D structure holding hydrogel network is synthesized.

Electrophoretic fabrication of a robust chitosan/polyethylene glycol/polydopamine composite film for UV-shielding application.

The film-forming process of chitosan composite films is an important issue because it affects their experimental design, chemicals used, and feasibility of large-scaled fabrication. In this work, electrophoresis is employed to produce chitosan composite films with significantly reduced processing time and environmentally friendly chemicals. With the addition of hydrogen peroxide and polyethylene glycol, the parasitic hydrogen bubble formation during the electrophoresis of chitosan and polydopamine is effectively inhibited that leads to the formation of a defectless chitosan/polyethylene glycol/polydopamine composite film which could be removed from the substrate readily.

Efficiency of CNT-based rotation transmission nanosystem in water.

Carbon nanotubes (CNTs) have been widely used as the motor and rotor in a rotational transmission nanosystem (RTnS), whose function is to transfer the input rotational frequency of the motor into the output frequency of the rotor through motor-rotor interactions. A wide range of techniques has been explored to achieve a CNT-based RTnS with a stable and adjustable transmission. In this work, a CNT-based rotor is partly immersed into a water box and the associated water-rotor interaction leads to effective manipulation of the transmission efficiency of RTnS.

Leveraging the water electrolysis reaction in bipolar electrophoresis to form robust and defectless chitosan films.

Electrophoresis of chitosan and its composites are widely used to form a coating on selective substrates, but the parasitic water electrolysis causes structural defects that weaken the resulting film. In this work, we demonstrate a bipolar electrophoresis technique that leverages the water electrolysis to produce a chitosan film with less porosity and surface cavities. The process involves a negative bias to deposit the protonated chitosan molecules from the solution, followed by a positive bias to remove the entrapped hydrogen bubbles via the re-protonation of chitosan deposit.

Formation of Free-Standing Inverse Opals with Gradient Pores.

We demonstrate the fabrication of free-standing inverse opals with gradient pores via a combination of electrophoresis and electroplating techniques. Our processing scheme starts with the preparation of multilayer colloidal crystals by conducting sequential electrophoresis with polystyrene (PS) microspheres in different sizes (300, 600, and 1000 nm). The critical factors affecting the stacking of individual colloidal crystals are discussed and relevant electrophoresis parameters are identified so the larger PS microspheres are assembled successively atop of smaller ones in an orderly manner.

Green Synthesis of Ni@PEDOT and Ni@PEDOT/Au (Core@Shell) Inverse Opals for Simultaneous Detection of Ascorbic Acid, Dopamine, and Uric Acid.

We demonstrate a water-based synthetic route to fabricate composite inverse opals for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Our process involves the conformal deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) and PEDOT/Au on the skeletons of Ni inverse opals via cyclic voltammetric scans (CV) to initiate the electropolymerization of 3,4-ethylenedioxythiophene (EDOT) monomers. The resulting samples, Ni@PEDOT, and Ni@PEDOT/Au inverse opals, exhibit a three-dimensional ordered macroporous platform with a large surface area and interconnected pore channels, desirable attributes for facile mass transfer and strong reaction for analytes.

Facile Synthesis of CoO@CoO@Co Gradient Core@Shell Nanoparticles and Their Applications for Oxygen Evolution and Reduction in Alkaline Electrolytes.

We demonstrate a facile fabrication scheme for CoO@CoO@Co (gradient core@shell) nanoparticles on graphene and explore their electrocatalytic potentials for an oxygen evolution reaction (OER) and an oxygen reduction reaction (ORR) in alkaline electrolytes. The synthetic approach begins with the preparation of CoO nanoparticles via a hydrothermal process, which is followed by a controlled hydrogen reduction treatment to render nanoparticles with radial constituents of CoO/CoO/Co (inside/outside). X-ray diffraction patterns confirm the formation of crystalline CoO nanoparticles, and their gradual transformation to cubic CoO and fcc Co on the surface.

Synthesis of IrO decorated core-shell PS@PPyNH microspheres for bio-interface application.

In this paper, an effective approach is demonstrated for the fabrication of IrO-decorated polystyrene@functionalized polypyrrole (core@shell; PS@PPyNH) microspheres. The synthesis begins with the preparation of monodispersive PS microspheres with a diameter of 490 nm, by a process of emulsifier-free emulsion polymerization, followed by a copolymerization process involving pyrrole and PyNH monomers in a PS microsphere aqueous suspension, to produce uniform PS@PPyNH microspheres with a diameter of 536 nm. The loading of 2 nm IrO nanoparticles onto the PS@PPyNH microspheres can be easily adjusted by tuning the pH value of the IrO colloidal solution and the PS@PPyNH suspension.

Improved Charge Pump Design and Ex Vivo Experimental Validation of CMOS 256-Pixel Photovoltaic-Powered Subretinal Prosthetic Chip.

An improved design of CMOS 256-pixel photovoltaic-powered implantable chip for subretinal prostheses is presented. In the proposed subretinal chip, a high-efficiency fully-integrated 4× charge pump is designed and integrated with on-chip photovoltaic (PV) cells and a 256-pixel array with active pixel sensors (APS) for image light sensing, biphasic constant current stimulators, and electrodes. Thus the PV voltage generated by infrared (IR) light can be boosted to above 1V so that the charge injection is increased.

Critical Output Torque of a GHz CNT-Based Rotation Transmission System Via Axial Interface Friction at Low Temperature.

It was discovered that a sudden jump of the output torque moment from a rotation transmission nanosystem made from carbon nanotubes (CNTs) occurred when decreasing the system temperature. In the nanosystem from coaxial-layout CNTs, the motor with specified rotational frequency () can drive the inner tube (rotor) to rotate in the outer tubes. When the axial gap between the motor and the rotor was fixed, the friction between their neighbor edges was stronger at a lower temperature.

Highly sensitive/selective 3D nanostructured immunoparticle-based interface on a multichannel sensor array for detecting amyloid-beta in Alzheimer's disease.

Accumulation of β-amyloid (Aβ) peptides is highly associated with Alzheimer's disease (AD) progression in prevailing studies. The successful development of an ultrasensitive detection assay for Aβ is a challenging task, especially from blood-based samples. We have developed a one-step electrophoresis/electropolymerization strategy for preparing a CSIP hierarchical immunoelectrochemical interface that is easily integrated into a PoCT device.