We have developed a novel composite filler with Poly(3,4-ethylenedioxythiophene) : poly(styrenesulfonic acid) (PEDOT:PSS), a biocompatible organic conductive polymer, adsorbed on carbon particles for biological electrodes. This composite filler enables to fabricate high-performance biological electrodes simply by adding it to resin in the same way as conventional conductive fillers. The fabricated electrodes achieve ion exchange properties similar to those of PEDOT:PSS polymers and therefore low skin and electrode contact impedance. Electroencephalogram (EEG) measurements show that these electrodes capture various brain activities and exhibit high correlation (≥ 0.9) to commercially available wet and AgCl electrodes. Additionally, each electrode can be molded into various shapes and structures while retaining its electrode characteristics. Therefore, the proposed electrode is promising for EEG measurement, which requires high comfort and signal quality.
Inspired by mechanosensitive potassium channels found in nature, we developed a fluorinated amphiphilic cyclophane composed of fluorinated rigid aromatic units connected via flexible hydrophilic octa(ethylene glycol) chains. Microscopic and emission spectroscopic studies revealed that the cyclophane could be incorporated into the hydrophobic layer of the lipid bilayer membranes and self-assembled to form a supramolecular transmembrane ion channel. Current recording measurements using cyclophane-containing planer lipid bilayer membranes successfully demonstrated an efficient transmembrane ion transport. We also demonstrated that the ion transport property was sensitive to the mechanical forces applied to the membranes. In addition, ion transport assays using pH-sensitive fluorescence dye revealed that the supramolecular channel possesses potassium ion selectivity. We also performed all-atom hybrid quantum-mechanical/molecular mechanical simulations to assess the channel structures at atomic resolution and the mechanism of selective potassium ion transport. This research demonstrated the first example of a synthetic mechanosensitive potassium channel, which would open a new door to sensing and manipulating biologically important processes and purification of key materials in industries.
Abstract A chiral ligand for the rhodium‐catalyzed asymmetric 1,4‐addition of an arylboronic acid to a coumarin substrate that could markedly reduce catalyst loading was developed using interplay between theoretical and experimental approaches. Evaluation of the transition states for insertion and for hydrolysis of intermediate complexes (which were emphasized in response to the experimental results) using DFT calculations at the B97D/6‐31G(d) level with the LANL2DZ basis set for rhodium revealed that: (i) the electron‐poor nature of the ligands and (ii) CH–π interactions between the ligand and coumarin substrates played significant roles in both acceleration of insertion and inhibition of ArB(OH) 2 decomposition (protodeboronation). The computationally‐designed ligand, incorporating the above information, enabled a decrease in the catalyst loading to 0.025 mol% (S/C=4,000), which is less than one one‐hundredth relative to past catalyst loadings of typically 3 mol%, with almost complete enantioselectivity. Furthermore, the gram‐scale synthesis of the urological drug, ( R )‐tolterodine ( l )‐tartrate, was demonstrated without the need of intermediate purification. magnified image
Three kinds of sintering aids, LiBiO2, CuBi2O4 and LiBO2, were selected as sintering aids for the low temperature sintering of (Li0.04K0.52Na0.44)(Nb0.84Ta0.1Sb0.06)O3 (LF4) ceramics and the effects of these compounds on the sintering behavior of the LF4 ceramics was investigated. The addition of LiBiO2 decreased the sintering temperature of LF4 about 100°C but the effect was limited and the broadening of XRD peaks due to the degradation of crystallinity was observed. The CuBi2O4 was also effective to decrease the sintering temperature of LF4 ceramics but a secondary phase was formed when a large amount of CuBi2O4 was added. The addition of a small amount of LiBO2 was very effective to decrease the sintering temperature of LF4 ceramics. By optimizing the sintering conditions, ceramics with the relative density of 95% were obtained at 950°C which was lower than the melting point of Ag. Li ions in LiBO2 were incorporated into the LF4 lattices, giving rise to the degradation of piezoelectric properties through the change of crystalline phase. The addition of excess Na with LiBO2 restricted the incorporation of Li ions into the lattice. Ceramics sintered at 950°C showed the relative permittivity of 738 and the d33 constant of 138 pC/N at room temperature.
Abstract Biological membranes play pivotal roles in the cellular activities. Transmembrane proteins are the central molecules that conduct membrane-mediated biochemical functions such as signal transduction and substance transportation. Not only the molecular functions but also the supramolecular properties of the transmembrane proteins such as self-assembly, delocalization, orientation and signal response are essential for controlling cellular activities. Here we report anisotropic ligand responses of a synthetic multipass transmembrane ion channel. An unsymmetrical molecular structure allows for oriented insertion of the synthetic amphiphile to a bilayer by addition to a pre-formed membrane. Complexation with a ligand prompts ion transportation by forming a supramolecular channel, and removal of the ligand deactivates the transportation function. Biomimetic regulation of the synthetic channel by agonistic and antagonistic ligands is also demonstrated not only in an artificial membrane but also in a biological membrane of a living cell.
We demonstrate in situ temperature-measurements conducted under microwave irradiation, for obtaining the accurate temperature of chemical reaction nanospaces.
