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