Keiichi Torimitsu

Highly Conductive Stretchable and Biocompatible Electrode–Hydrogel Hybrids for Advanced Tissue Engineering

Hydrogel-based, molecular permeable electronic devices are considered to be promising for electrical stimulation and recording of living tissues, either in vivo or in vitro. This study reports the fabrication of the first hydrogel-based devices that remain highly electrically conductive under substantial stretch and bending. Using a simple technique involving a combination of chemical polymerization and electropolymerization of poly (3,4-ethylenedioxythiophene) (PEDOT), a tight bonding of a conductive composite of PEDOT and polyurethane (PU) to an elastic double-network hydrogel is achieved to make fully organic PEDOT/PU-hydrogel hybrids. Their response to repeated bending, mechanical stretching, hydration-dessication cycles, storage in aqueous condition for up to 6 months, and autoclaving is assessed, demonstrating excellent stability, without any mechanical or electrical damage. The hybrids exhibit a high electrical conductivity of up to 120 S cm(-1) at 100% elongation. The adhesion, proliferation, and differentiation of neural and muscle cells cultured on these hybrids are demonstrated, as well as the fabrication of 3D hybrids, advancing the field of tissue engineering with integrated electronics.

Self-assembly of vesicle nanoarrays on Si: A potential route to high-density functional protein arrays

The authors show that 100nm unilamellar thiol-tagged vesicles bind discretely and specifically to Au nanodots formed on a Si surface. An array of such dots, consisting of 20nm Au–Si three-dimensional islands, is formed by self-assembly on terraces of small-angle-miscut Si(111) after Au deposition. Consequently, both the formation of the nanopattern and the subsequent attachment of the vesicles are self-organized and occur without the need for any “top-down” lithographic processes. This approach has the potential to provide the basis of a low-cost, high-density nanoarray for use in proteomics and drug discovery.

Ligand-induced structural changes in a membrane-reconstituted ion channel observed with atomic force microscopy

We investigated structural changes in ligand-gated ion channel proteins reconstituted into supported lipid bilayers. The ion channels extracellular parts were highly dynamic and exhibited agonist-induced changes, which were inhibited by antagonists. Our data demonstrate that, by using small exogenously applied compounds (i.e., ligands), ion channel proteins reconstituted into supported lipid bilayers on a substrate can be controlled.

Bioanalytical Devices for Highly Selective Measurement of Transmitters From Cultured Cells

Two types of devices for highly selective measurement of biomolecules were fabricated. One consists of a dual electrochemical flow channel for differential measurement of neurotransmitters. The other is integrated with micro-reactor having a number of micro-pillars that remove interferent effectively in the small volume.