Jump to main content
Jump to site search

Volume 131, 2006
Previous Article Next Article

Metalloprotein tunnel junctions: compressional modulation of barrier height and transport mechanism

Author affiliations

Abstract

Though the incorporation of sensory or potentially-switchable biological entities into electronic devices brings with it a number of complicating issues associated with hydration, structural complexity/delicacy, and low conductance, the possibility of resolving properties of fundamental importance (such as the influence of protein fold on conductance) at a molecularly-resolved level, are exciting. Our ability to analyse charge transport through a biological macromolecule remains, though, a significant practical and theoretical challenge. Though much information can be gained by carrying out such examinations at a molecular level, there exist few methods where such controlled analyses are, in fact, feasible. Here we report on the electron transport characteristics of a blue copper metalloprotein as characterized by conductive-probe atomic force microscopy. At very low imposed force, contact resistance is high, electrical contact unstable, and the junction undergoes dielectric breakdown at 1.1–1.5 GV m−1. At increased applied force, the current–voltage characteristics are entirely reproducible and well-described by a Simmons (non-resonant) tunnelling model. Though highly resistive, observations demonstrate the ability of the protein matrix to mediate appreciable tunnelling current. Non-resonant behaviour is consistent with observations of bias-independent tunnelling imaging. In fitting observed transport characteristics to this model, it is possible to deconvolute barrier height and length at specific experimental conditions and, specifically, to monitor the modulation of these parameters by imposed compressional force. At higher field spectroscopic features assignable to metal based density of states are reproducibly observed. These vanish in a force regime where the tunnel barrier to direct tip–sample communication decreases.

Back to tab navigation

Publication details

The article was received on 03 Jun 2005, accepted on 13 Jun 2005 and first published on 14 Oct 2005


Article type: Paper
DOI: 10.1039/B507854G
Citation: Faraday Discuss., 2006,131, 167-179
  •   Request permissions

    Metalloprotein tunnel junctions: compressional modulation of barrier height and transport mechanism

    J. J. Davis, N. Wang, A. Morgan, T. Zhang and J. Zhao, Faraday Discuss., 2006, 131, 167
    DOI: 10.1039/B507854G

Search articles by author

Spotlight

Advertisements