|Andrea Alessandrini1, Stefano Frabboni1,2, and Paolo Facci1
1INFM National Research Center on "nanoStructures and bioSystems at Surfaces" (S3), University of Modena and Reggio Emilia, Via Campi 213A, I-41100 Modena, Italy , and
Metalloproteins are redox biomolecules naturally shuttling electrons with high efficiency between molecular partners. As such, they are candidates of choice for bioelectronics. In this work we have used bacterial blue-copper protein azurin, hosted in a nanometer gap between two electrically biased gold electrodes, to demonstrate an electrochemically gated single-molecule transistor operating in aqueous environment. Gold-chemisorbed azurin shows a resonant behavior in redox level-assisted tunnelling current upon changing electrode potential and a related variation in tunnelling barrier transparency which can be exploited to switch electron flow through it. These results suggest the wet approach to molecular electronics as a viable method for exploiting electron transfer properties of highly specialized biomolecules.