Electron tunneling in a metal-protein-metal junction investigated by scanning tunneling and conductive atomic force spectroscopies

The electron tunneling across a redox protein covalently bound to Au(111) electrode is investigated by both scanning tunneling and conductive atomic force spectroscopies. Although the current-voltage curves, detected by the two techniques, refer to different tunneling junctions, they are analyzed within the same transport model. By evaluating the electron transmission probability of each element constituting the tunneling junctions, the electron transport properties of the protein macromolecule are singled out. These results represent an advancement in understanding current flow through protein macromolecule in tunneling experiments, also in the perspectives of applications in nanobioelectronics. (c) 2006 American Institute of Physics.