Tatyana Bendikov1,Jerry Fereiro1,2,Cunlan Guo1,3,Israel Pecht1,Mordechai Sheves1,David Cahen1,4
Weizmann Institute of Science1,Indian Institute of Science Education & Research2,Wuhan University3,Bar-Ilan University4
Tatyana Bendikov1,Jerry Fereiro1,2,Cunlan Guo1,3,Israel Pecht1,Mordechai Sheves1,David Cahen1,4
Weizmann Institute of Science1,Indian Institute of Science Education & Research2,Wuhan University3,Bar-Ilan University4
<br/>Biomolecules such as proteins and peptides are potential candidates for building diverse functional electronic devices. Measuring and controlling electron transport (<i>ETp</i>) through these molecules, especially, as assemblies on solid substrates, i.e., part of an electronic device structure with solid electrodes, is a major goal of bio-molecular electronics. The electronic structure of the peptide/protein monolayer and/or its orientation in contact with an electrode can be directly related to the energy barrier and electrode/molecule coupling in the resulting junction.<br/>Ultraviolet and X-ray Photoelectron Spectroscopies (UPS, XPS) with their high surface sensitivity have been used extensively to study the electronic and chemical structure of <i>molecular</i> thin films or monolayers on solid surfaces. Here we show how UPS and XPS measurements can provide a crucial information for understanding the mechanism(s) of <i>ETp</i> through biomolecule/Au electrode-containing junctions.<br/>In the first example we show how the spatial position of a singe tryptophan “dopant” in a linear oligo-alanine chain may significantly influence <i>ETp</i> across a self-assembled monolayer of these peptides between gold contacts.<sup>1</sup> In the second example we explore the effect of the side-chain of the peptide (<i>2Ala</i> vs <i>2Trp</i>) on its electronic properties.<sup>2</sup><br/>In the two next examples, the bacterial electron transfer protein Azurin (<i>Az</i>)<sup> 3</sup> and a mutant (<i>N42C Az</i>)<sup>4</sup> are studied on Au substrates. We find that the <i>ETp</i> mechanism can be changed by changing just a linker (binding)<sup>3</sup> or the orientation<sup>4</sup> of the protein with respect to the Au substrate.<br/>Finally, we demonstrate that the direction of current rectification and the conductance-voltage characteristics of the Photosystem 1 complex (<i>PS1</i>) can be controlled by its orientation on Au substrates.<sup>5</sup><br/><br/><br/>1. C. Guo et al, <i>PNAS</i>, 113, <b>2016</b>, 10785-10790.<br/>2. C. Guo et al, <i>PCCP</i>, 20, <b>2018</b>, 6860-6867.<br/>3. J. A. Fereiro et al, <i>JACS</i>, 140, <b>2018</b>, 13317-13326.<br/>4. J. A. Fereiro et al, <i>JACS</i>, 142, <b>2020</b>, 19217-19225.<br/>5. J. A. Fereiro et al, <i>Small</i>, <b>2022</b>, submitted.