Carbon-nanotube-modified electrodes for the direct bioelectrochemistry of pseudoazurin

Anthony Guiseppi-Elie, Sean Brahim, Gary Wnek, Ray Baughman

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

The bioelectrochemistry of the blue copper protein, pseudoazurin, at glassy carbon and platinum electrodes that were modified with single-wall carbon nanotubes (SWNTs) was investigated by multiple scan rate cyclic voltammetry. The protein showed reversible electrochemical behavior at both bare glassy carbon electrodes (GCEs) and SWNT-modified GCEs (SWNT|GCEs); however, direct electrochemistry was not observed at any of the platinum electrodes. The effect of the carbon nanotubes at the GCE was to amplify the current response 1000-fold (nA at bare GCE to μA at SWNT|GCE), increase the apparent diffusion coefficient Dapp of the solution-borne protein by three orders of magnitude, from 1.35 × 10-11 at bare GCE to 7.06 × 10-8 cm2 s-1 at SWNT|GCE, and increase the heterogeneous electron transfer rate constant ks threefold, from 1.7 × 10-2 cm s-1 at bare GCE to 5.3 × 10-2 cm s-1 at SWNT|GCE. Pseudoazurin was also found to spontaneously adsorb onto the nanotube-modified GCE surface. Well-resolved voltammograms indicating quasi-reversible faradaic responses were obtained for the adsorbed protein in phosphate buffer, with Ipc and Ipa values now greater than corresponding values for solution-borne pseudoazurin at SWNTIGCEs and with significantly reduced ΔEp values. The largest electron transfer rate constant of 1.7 × 10-1 cm s-1 was achieved with adsorbed pseudoazurin at the SWNTIGCE surface in deaerated buffer solution consistent with its presumed role in anaerobic respiration of some bacteria.

Original languageEnglish (US)
Pages (from-to)83-92
Number of pages10
JournalNanobiotechnology
Volume1
Issue number1
DOIs
StatePublished - 2005

Keywords

  • Carbon nanotubes
  • Metalloproteins
  • Nanoelectrodes

ASJC Scopus subject areas

  • Bioengineering
  • Biomedical Engineering
  • Molecular Biology

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