Layer-by-layer PMIRRAS characterization of DMPC bilayers deposited on a Au(111) electrode surface

Nuria Garcia-Araez, Christa L. Brosseau, Paramaconi Rodriguez, Jacek Lipkowski*, Paramaconi Rodriguez

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

58 Citations (Scopus)

Abstract

A combination of Langmuir-Blodgett and Langmuir-Schaefer techniques was employed to deposit 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayers at a gold electrode surface. One leaflet consisted of hydrogen-substituted acyl chains, and the second leaflet was composed of molecules with deuterium-substituted acyl chains. This architecture allowed for layer-by-layer analysis of the structure of the bilayer. Photon polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was used to determine the conformation and orientation of the acyl chains of DMPC molecules in the individual leaflets as a function of the potential applied to the gold electrode. The bilayer is adsorbed onto the metal surface when the field applied to the membrane does not exceed ∼108 V/m. When adsorbed, the bottom leaflet is in contact with a hydrophobic metal surface, and the top leaflet is interacting with the aqueous solution. The asymmetry of the environment has an effect on the orientation of the DMPC molecules in each leaflet. The tilt angle of the acyl chains of the DMPC molecules in the bottom leaflet that is in contact with the gold is ∼10° smaller than that observed for the top leaflet that is exposed to the solution. These studies provide direct evidence that the structure of a phospholipid bilayer deposited at an electrode surface is affected by interaction with the metal.

Original languageEnglish
Pages (from-to)10365-10371
Number of pages7
JournalLangmuir
Volume22
Issue number25
DOIs
Publication statusPublished - 5 Dec 2006

ASJC Scopus subject areas

  • Colloid and Surface Chemistry
  • Physical and Theoretical Chemistry

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