Tuning electronic transport via hepta-alanine peptides junction by tryptophan doping

Cunlan Guo, Xi Yu, Sivan Refaely-Abramson, Lior Sepunaru, Tatyana Bendikov, Israel Pecht, Leeor Kronik, Ayelet Vilan, Mordechai Sheves, David Cahen

Research output: Contribution to journalArticlepeer-review

73 Scopus citations


Charge migration for electron transfer via the polypeptide matrix of proteins is a key process in biological energy conversion and signaling systems. It is sensitive to the sequence of amino acids composing the protein and, therefore, offers a tool for chemical control of charge transport across biomaterial-based devices. We designed a series of linear oligoalanine peptides with a single tryptophan substitution that acts as a "dopant," introducing an energy level closer to the electrodes' Fermi level than that of the alanine homopeptide. We investigated the solid-state electron transport (ETp) across a selfassembled monolayer of these peptides between gold contacts. The single tryptophan "doping" markedly increased the conductance of the peptide chain, especially when its location in the sequence is close to the electrodes. Combining inelastic tunneling spectroscopy, UV photoelectron spectroscopy, electronic structure calculations by advanced density-functional theory, and dc current-voltage analysis, the role of tryptophan in ETp is rationalized by charge tunneling across a heterogeneous energy barrier, via electronic states of alanine and tryptophan, and by relatively efficient direct coupling of tryptophan to a Au electrode. These results reveal a controlled way of modulating the electrical properties of molecular junctions by tailormade "building block" peptides.

Original languageEnglish
Pages (from-to)10785-10790
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number39
StatePublished - 27 Sep 2016
Externally publishedYes


  • Doping
  • Electron transport
  • Inelastic electron tunneling spectroscopy
  • Oligopeptide
  • Self-assembled monolayer


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