Chen Maohui, Li Ming, Brosseau Christa L, Lipkowski Jacek
Department of Chemistry, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Langmuir. 2009 Jan 20;25(2):1028-37. doi: 10.1021/la802839f.
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.
原子力显微镜（AFM）用于表征在金（111）电极表面由70摩尔％的1,2 - 二肉豆蔻酰 - sn - 甘油 - 3 - 磷酸胆碱（DMPC）和30摩尔％的胆固醇组成的磷脂双层。结果表明，添加胆固醇可缓解膜弹性应力，增加膜厚度并降低缺陷密度。支撑在金电极表面的混合DMPC - 胆固醇双层的厚度和热致性质与单层囊泡中混合膜的性质非常相似。研究了支撑膜在负于零电荷电位E（pzc）时的稳定性。该研究表明，只要施加的电位（E - E（pzc））小于-0.3 V，支撑在金电极表面的双层就是稳定的。在更大的极化下，会观察到膜的肿胀。大于-1 V的极化会导致双层从金表面电极润湿。在这些负电位下，双层与金属表面保持紧密接近，由约2 nm厚的电解质层与其隔开。
