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 phosphafidylcoline (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 B-SiO₂ substrate, a hexagonal crystal structure of BR and PC with a size of 0.5 nm 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.