The electrochemical phase behaviour of chemically asymmetric lipid bilayers supported at Au(111) electrodes

Elena Madrid, Sarah L. Horswell

Research output: Contribution to journalArticlepeer-review

2 Citations (SciVal)

Abstract

Chemically asymmetric phospholipid bilayers supported on Au(111) surfaces have been studied with differential capacitance and chronocoulometry measurements. The bilayers were prepared using Langmuir-Blodgett deposition, followed by Langmuir-Schaeffer deposition using a different molecule. Combinations of three phospholipids with common hydrocarbon tail groups were compared: dimyristoyl phosphatidyl choline (DMPC), dimyristoyl phosphatidyl ethanolamine (DMPE) and dimyristoyl phosphatidyl serine (DMPS). DMPC and DMPE are zwitterionic and DMPS is anionic in the electrolyte used. The asymmetric bilayers containing DMPS gave distinct electrochemical responses depending on whether the DMPS was deposited first, onto Au, or second, onto another lipid, indicating that asymmetry was maintained over the timescale of the experiment. The results for DMPE and DMPC combinations suggest similar headgroup conformations in the two bilayers. The relationship between the location of the charged molecule and the electrochemical properties is complex but in all cases, DMPS tends to raise bilayer capacitance and DMPE tends to lower capacitance. These observations can be explained by the relatively higher solvation of the charged DMPS molecules and tight packing of DMPE molecules, which leads to exclusion of solvent from the bilayer.

Original languageEnglish
Number of pages9
JournalJournal of Electroanalytical Chemistry
Early online date3 Nov 2017
DOIs
Publication statusE-pub ahead of print - 3 Nov 2017

Keywords

  • Adsorption
  • Asymmetric bilayer
  • Capacitance
  • Electrochemistry
  • Phospholipid

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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