Papers by Author: Masayoshi Tanaka

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Authors: T. Niwa, Masayoshi Tanaka, Takatoshi Kinoshita
Abstract: In order to construct an intelligent functional nano-interface, the self-organized structure of Langmuir-Blodgett (LB) film was investigated by atomic force microscopy (AFM). As a building block, a monodisperse loop-helix-helix triblock copolypeptide containing the helix of which hydrophobic L-leucine residues align on a single face, “leucine zipper”, was synthesized by recombinant DNA techniques with a designed amino acid sequence. AFM observation on the surface structure of LB films constructed at surface pressures of 2, 5 and 18 mN/m revealed that structural transition from ring- or disk-like aggregations to a lane-like fabrication occurred with compression of the copolypeptide membrane on the water of pH 4. The leucine zipper in the copolypeptide was suggested to perform as an important basis for nanostructure formation through a hydrophobic interaction. Exploitation of the recognition and specific binding sites in the copolypeptide will allow the self-assembling mechanism of the copolypeptide to be developed to a novel nano-template.
Authors: R. Tominaga, M. Sivakumar, Masayoshi Tanaka, Takatoshi Kinoshita
Abstract: SiO2 thin-films were prepared by thermal oxidation method. It showed uniform color based on the thin-film interference of visible light. Then we made biotin antenna on the top of SiO2 thin-film. Biotin is one of the vitamins and it has high association constant with protein avidin. After immersed the substrate into avidin solution, certain color changes based on the self-assembling of avidin on its surface were observed. By the immersing these substrates into mono-dispersed polystyrene particle solution, a polystyrene particle layer was formed onto avidin SAMs and it brought dynamic interference color change. As a result, this substrate could sense the avidin molecules over 1.0×10-8M of its concentration by naked eyes.
Authors: A. Kato, K. Hase, Masayoshi Tanaka, Takatoshi Kinoshita
Abstract: Monodisperse polystyrene (PS) particle multilayer with coherent structure wasconstructed by Langmuir-Blodgett (LB) method. The reflectance spectra of the particle multilayer with various incident angles indicated that the constructed particle multilayer showed a typical optical character of the conventional multilayer having different refractive index. It was suggested that the particle multilayer was treated as a multilayer constructed by polymer layer and air layer. The fact was strongly supported by a simulation of the corresponding model, which was designed for analyzing optical characterization of the particle multilayer. The refractive index of the particle multilayer with nickel ion was also discussed by simulation, suggesting that a theoretical designing of the particle multilayer with various refractive index would be possible. It was also suggested that coordination of metal ion on the surface of the particle would be enhanced its contribution for increasing the refractive index.
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