Electroreflectance spectroscopic study of the electron transfer rate of cytochrome c electrostatically immobilized on the ω-carboxyl alkanethiol monolayer modified gold electrode

Zhi Qiang Feng, Shinichiro Imabayashi, Takashi Kakiuchi, Katsumi Niki

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Abstract

Horse heart cytochrome c was immobilized electrostatically on self-assembled monolayers (SAMs) of carboxylic-acid-terminated alkanethiols, HS(CH2)nCOOH (n = 2, 10) on gold electrodes, The rate constants of the electrode reaction of cytochrome c at the SAM-modified gold electrodes were determined by the frequency dependence of a.c. modulated UV-visible electroreflectance signals. The apparent standard electrode reaction rate constants of cytochrome c were 880 s-1 and 72 s-1 at the HS(CH2)2COOH and HS(CH2)10COOH SAM modified gold electrodes respectively. The rate constant at HS(CH2)2COOH was much smaller than expected from Marcus theory. However, the rate constant at HS(CH2)10COOH could be explained in terms of the through-bond tunnelling mechanism with tunnelling parameter β = 8.2 nm-1.

Original languageEnglish
Pages (from-to)149-154
Number of pages6
JournalJournal of Electroanalytical Chemistry
Volume394
Issue number1-2
DOIs
Publication statusPublished - 1995 Sep 19

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Keywords

  • Cytochrome c
  • Electron transfer rate
  • Gold electrode
  • Self-assembled monolayers

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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