title: AFM studies of the effect of temperature and electric field on the structure of a DMPC-cholesterol bilayer supported on a Au(111) electrode surface.
abstract: Atomic force microscopy (AFM) was used to characterize a phospholipid bilayer composed of 70 mol % 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 30 mol % cholesterol, at a Au(111) electrode surface. Results indicate that addition of cholesterol relaxes membrane elastic stress, increases membrane thickness, and reduces defect density. The thickness and thermotropic properties of the mixed DMPC-cholesterol bilayer supported at the gold electrode surface are quite similar to the properties of the mixed membrane in unilamellar vesicles. The stability of the supported membrane at potentials negative to the potential of zero charge E(pzc) was investigated. This study demonstrates that the bilayer supported at the gold electrode surface is stable provided the applied potential (E - E(pzc)) is less than -0.3 V. At larger polarizations, swelling of the membrane is observed. Polarizations larger than -1 V cause electrodewetting of the bilayer from the gold surface. At these negative potentials, the bilayer remains in close proximity to the metal surface, separated from it by a approximately 2 nm thick layer of electrolyte.
authors.affiliation: Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Maohui
authors.initials: M
authors.lastname: Chen
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.forename: Christa L
authors.initials: CL
authors.lastname: Brosseau
authors.forename: Jacek
authors.initials: J
authors.lastname: Lipkowski
mesh_terms: D002784:Cholesterol / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry*; D004566:Electrodes; D004574:Electromagnetic Fields; D006046:Gold / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods; D010316:Particle Size; D013499:Surface Properties; D013696:Temperature
chemical_list: D008051:Lipid Bilayers; D006046:Gold; D002784:Cholesterol; D004134:Dimyristoylphosphatidylcholine