Electrodes Modified with Cast Lipid Films: The Effects of Lipid Composition on the Electrochemistry of Incorporated Amphiphilic Viologens

Maria T. Rojas, Mei Han, Angel E. Kaifer

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

The cyclic voltammetric behavior of N-ethyl-N′-octadecylviologen, 12+, and N-(cholesteryl acetate)-N′-ethylviologen, 22+, was studied in phosphatidylcholine films cast on the surface of glassy carbon electrodes. Both viologens exhibited diffusion-controlled voltammetric behavior under these conditions. Visible spectroscopy after exhaustive one-electron reduction of the viologen-containing lipid films revealed a low level of dimerization in spite of the large local concentration of reduced viologen, 1+. Apparent diffusion coefficients for 12+ were found to be essentially independent from its film concentration, suggesting that charge propagation takes place via actual diffusion of the amphiphilic viologen in the lipid film. Voltammetric currents for both 12+ and 22+ were observed to be highly dependent on the degree of saturation of the lipid's fatty acyl residues, generally increasing with the degree of unsaturation. Currents also increased with temperature, but no clear break points, indicative of phase transitions, were detected. Cholesterol addition to fully unsaturated lipid films did not affect the voltammetric currents while it increased the currents observed in fully saturated lipid films.

Original languageEnglish (US)
Pages (from-to)1627-1632
Number of pages6
JournalLangmuir
Volume8
Issue number6
DOIs
StatePublished - Jun 1 1992

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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