Solid-State Electron Transport via the Protein Azurin is Temperature-Independent down to 4 K

Ben Kayser, Jerry A. Fereiro, Rajarshi Bhattacharyya, Sidney R. Cohen, Ayelet Vilan, Israel Pecht, Mordechai Sheves, David Cahen

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27 Scopus citations


Solid-state electronic transport (ETp) via the electron-transfer copper protein azurin (Az) was measured in Au/Az/Au junction configurations down to 4 K, the lowest temperature for solid-state protein-based junctions. Not only does lowering the temperature help when observing fine features of electronic transport, but it also limits possible electron transport mechanisms. Practically, wire-bonded devices-on-chip, carrying Az-based microscopic junctions, were measured in liquid He, minimizing temperature gradients across the samples. Much smaller junctions, in conducting-probe atomic force microscopy measurements, served, between room temperature and the protein's denaturation temperature (∼323 K), to check that conductance behavior is independent of device configuration or contact nature and thus is a property of the protein itself. Temperature-independent currents were observed from ∼320 to 4 K. The experimental results were fitted to a single-level Landauer model to extract effective energy barrier and electrode-molecule coupling strength values and to compare data sets. Our results strongly support that quantum tunneling, rather than hopping, dominates ETp via Az.

Original languageEnglish
Pages (from-to)144-151
Number of pages8
JournalJournal of Physical Chemistry Letters
Issue number1
StatePublished - 2 Jan 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
Copyright © 2019 American Chemical Society.


We thank Prof. Moty Heiblum for access to the low-temperature measuring system and valuable guidance. J.A.F. is grateful to the Azrieli Foundation for the award of an Azrieli Fellowship. D.C. and M.S. thank the Israel Science Foundation and the German Science Foundation (DFG). M.S. holds the Katzir-Makineni Chair in Chemistry.

FundersFunder number
Deutsche Forschungsgemeinschaft
Israel Science Foundation
Azrieli Foundation


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