Fabrication and electrical characteristics of ferredoxin adsorbed poly-l-lysin/11-MUA hetero-self-assembly layer

A ferredoxin adsorbed hetero-self-assembled layer was fabricated by electrostatic attraction. 11-Mercaptoundecanoic acid (11-MUA) was deposited onto Au substrate and then poly-l-lysin (PL) was adsorbed on 11-MUA layer since PL was used as a bridging molecule for ferredoxin adsorption due to its net positive charge. Ferredoxin/PL/11-MUA structured hetero-layer was constructed due to the adsorption of negatively charged ferredoxin on positively charged PL/11-MUA hetero-layer. The surface of ferredoxin adsorbed PL/11-MUA layer was observed by atomic force microscope (AFM). The hetero-film formation was verified by surface plasmon resonance (SPR) measurement. The current flow and rectifying property based on the scanning tunneling spectroscopy (STS) I–V characteristics was achieved in the proposed hetero-layer. Thus, the hetero-layer structure of ferredoxin was functioned as the biomolecular diode with rectifying property. The proposed biomolecular diode can be usefully applied for the development of molecular-scale bioelectronic devices.