Molecular-scale biophotodiode consisting of a green fluorescent protein/cytochrome c self-assembled heterolayer

Abstract

A molecular photodiode that consists of a protein heterolayer is investigated at the molecular scale for construction of a bioelectronic device. Cytochrome $c$ and green fluorescent protein (GFP) were used as an electron acceptor and a sensitizer in the molecular layer by mimicking photosynthesis. A self-assembled monolayer of thiol-modified cytochrome $c$ was formed on Au-coated glass, and then GFP was adsorbed onto the cytochrome $c$ surface by electrostatic attraction. Photoinduced current was generated and the photoswitching property was observed by repeated step illumination. The rectifying property by scanning tunneling spectroscopy based current–voltage characteristics was achieved in the protein heterolayer. Thus, the proposed heterolayer functioned as a biomolecular photodiode with photocurrent generation and the rectifying property.