Resonant tunneling in protein junctions
30/04/18 13:55
Proteins play a fundamental role in numerous biological energy conversion processes such as photosynthesis, respiration, and a wide variety of enzymatic reactions. In recent years, redox proteins containing transition metal ion centers have been integrated into solid-state electronic junctions. The goal is to shed new light on the electron transfer mechanisms in these biomolecules, but also to investigate the possibility of using proteins as active elements in novel, bio-inspired electronic devices. In this context, recent experiments have shown that the electron transport through proteins can be surprisingly efficient. However, the origin of this efficiency and, in general, the underlying transport mechanisms remain largely unknown.
We have now shed new light on this fundamental problem in a work published in the Proceedings of the National Academy of Sciences of USA (PNAS) in collaboration with the group of David Cahen (Weizmann Institute of Science, Rehovot, Israel). In this work, we report low-temperature (10 K) electron transport measurements via monolayer junction based on the blue copper protein Azurin that strongly suggest that quantum tunneling is the dominant charge transport mechanism. In particular, we show that weakening the protein-electrode coupling by introducing a spacer, one can switch the electron transport from off-resonant to resonant tunneling, which has never been reported before in protein-based junctions. Moreover, we identified vibronic features of the Cu(II) coordination sphere in the transport characteristics that show directly the active role of the metal ion in the resonant tunneling. These results illustrate how quantum mechanical effects may dominate electron transport via protein-based junctions.
We have now shed new light on this fundamental problem in a work published in the Proceedings of the National Academy of Sciences of USA (PNAS) in collaboration with the group of David Cahen (Weizmann Institute of Science, Rehovot, Israel). In this work, we report low-temperature (10 K) electron transport measurements via monolayer junction based on the blue copper protein Azurin that strongly suggest that quantum tunneling is the dominant charge transport mechanism. In particular, we show that weakening the protein-electrode coupling by introducing a spacer, one can switch the electron transport from off-resonant to resonant tunneling, which has never been reported before in protein-based junctions. Moreover, we identified vibronic features of the Cu(II) coordination sphere in the transport characteristics that show directly the active role of the metal ion in the resonant tunneling. These results illustrate how quantum mechanical effects may dominate electron transport via protein-based junctions.
