Yutaka Tsujiuchi

Preparation of hydrogenated amorphous silicon by ECR plasma sputtering and the effect on retinoic acid and membrane protein polypeptides

Abstract Thin films of amorphous silicon and hydrogenated amorphous silicon were prepared by ECR plasma sputtering and their characteristics are studied. These films exhibited several amorphous states and smoothness of less than 0.8 nm. Langmuir–Blodgett (LB) films of retinoic acid or polypeptide including the alpha helix region of membrane protein were jointed with these amorphous silicon films. The hybrid films exhibited an oriented arrangement of molecules. The UV absorption spectrum of the LB films of retinoic acid based on hydrogenated amorphous silicon films exhibited a novel absorption at the wavelength 500 nm not reported before.

Visible Absorption Properties of Retinoic Acid Controlled on Hydrogenated Amorphous Silicon Thin Film

Langmuir–Blodgett (LB) films of retinoic acid and LB films of retinoic acid mixed with a peptide that contains an alanine–lysine–valine (AKV) amino acid sequence deposited on a hydrogenated amorphous silicon (a-Si:H) film prepared by electron cyclotron resonance (ECR) plasma sputtering were fabricated, and their light absorption spectrums were compared. A specific visible light absorption at approximately 500 nm occurred in a film that had a film thickness of more than 80 nm and a hydrogen concentration of more than 20% in the sputtering process gas. Mixing the AKV sequence peptide with retinoic acid caused a 6 nm blueshift, from 363 to 357 nm, of the absorption maximum of the composite LB film on a SiO2 substrate. Using the same peptide, a large 30 nm blueshift, from 500 to 470 nm, was induced in the composite LB film on the a-Si:H film.

Surface Structural Comparison of Composite Film of Bacteriorhodopsin and Phosphatidylcholine Fabricated on Amorphous Silicon Dioxide, Crystal Silicon Dioxide, and Hydrogenated Amorphous Silicon

A surface structural comparison of composite film of bacteriorhodopsin (BR) and phosphatidylcoline (PC) fabricated on a layered fatty acid film on a substrate of amorphous silicon dioxide (a-SiO2), crystal silicon dioxide (c-SiO2), or hydrogenated amorphous silicon (a-Si:H) was conducted to investigate the effect of substrate structure on the Langmuir–Blodgett (LB) film fabrication of membrane protein by direct force microscopy (DFM) measurement. On the a-SiO2 substrate, a hexagonal crystal structure of BR and PC with a size of 0.5 µm was observed. However, on the c-SiO2 or a-Si:H substrate, the surface structural features of the composite LB films differed from each other on the shape of assemblies in themselves. In spite of the presence of fatty acid layers, the assemby of BR and PC depends on the structure of the bottom substrate.

M intermediate accumulation analysis of bacteriorhodopsin reconstituted with three partial peptides

Reconstituted bacteriorhodopsin containing helices C-G, A, and B has unique thermal structural change and photoreaction. Time evolution of photo reaction of bacteriorhodopsin reconstituted with three partial peptides in glycerol mixed purple membrane at around 196 K under irradiation by red light was analyzed by a proposed model. The absorption change of 560 nm and 405 nm with irradiation times was analyzed for the purpose of determining reaction rates of photo reaction of reconstituted bacteriorhodopsin and its product M intermediate. In this study it is shown that reaction rates of conversion from bacteriorhodopsin reconstituted with three partial peptides to the M intermediate can be explained by a set of linear differential equations. Although the rate of accumulation of M intermediate is as forty times smaller than that of the native bacteriorhodopsin, the accumulation was achieved, in spite of absence of peptide bond between peptides.

Light Absorption Property of the Thin Film Constituted from Dimyristoyl-Phosphatidylcoline and Retinoic Acid

To determine the adequate condition for construction of the thin film constituted from lipid and color pigment, hybrid films of dimyristoyl-phosphatidylcoline (DMPC) and retinoic acid (retA) in several molecular ratios (9: 1, 4: 1, 1: 1, 1: 4, 1: 9) were prepared by means of Langmuir Blodgett method. The result was that in the ratio of retA and DMPC by 4: 1, the film showed relatively large absorption of light at the wavelength of 360nm. The result indicates the molecular ratio of retA and DMPC is important factor for construction of hybrid film structure in that retA functions efficiently as a color pigment.