Insights into Solid-State Electron Transport through Proteins from Inelastic Tunneling Spectroscopy: The Case of Azurin

Xi Yu, Robert Lovrincic, Lior Sepunaru, Wenjie Li, Ayelet Vilan, Israel Pecht, Mordechai Sheves, David Cahen

Research output: Contribution to journalArticlepeer-review

49 Scopus citations

Abstract

Surprisingly efficient solid-state electron transport has recently been demonstrated through "dry" proteins (with only structural, tightly bound H2O left), suggesting proteins as promising candidates for molecular (bio)electronics. Using inelastic electron tunneling spectroscopy (IETS), we explored electron-phonon interaction in metal/protein/metal junctions, to help understand solid-state electronic transport across the redox protein azurin. To that end an oriented azurin monolayer on Au is contacted by soft Au electrodes. Characteristic vibrational modes of amide and amino acid side groups as well as of the azurin-electrode contact were observed, revealing the azurin native conformation in the junction and the critical role of side groups in the charge transport. The lack of abrupt changes in the conductance and the line shape of IETS point to far off-resonance tunneling as the dominant transport mechanism across azurin, in line with previously reported (and herein confirmed) azurin junctions. The inelastic current and hence electron-phonon interaction appear to be rather weak and comparable in magnitude with the inelastic fraction of tunneling current via alkyl chains, which may reflect the known structural rigidity of azurin.

Original languageEnglish
Pages (from-to)9955-9963
Number of pages9
JournalACS Nano
Volume9
Issue number10
DOIs
StatePublished - 27 Oct 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.

Keywords

  • electron transfer
  • inelastic electron tunneling spectroscopy
  • molecular electronics
  • phonon-coupled electron transport

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