Benz Marcel, Gutsmann Thomas, Chen Nianhuan, Tadmor Rafael, Israelachvili Jacob
Department of Chemical Engineering, Department of Physics, and Materials Research Laboratory, University of California, Santa Barbara, California 93106, USA.
Biophys J. 2004 Feb;86(2):870-9. doi: 10.1016/S0006-3495(04)74162-4.
Phospholipid bilayers were studied by means of atomic force microscopy (AFM) and a surface force apparatus (SFA). The stability of the supported bilayers was described by the amount of irregularities in the topography of the membrane by means of AFM and by the occurrence of hemifusion in the SFA, which is an indicator of defective bilayers. The bilayers, composed of lipids having the same headgroup but different chain lengths in the two leaflets, were prepared by Langmuir-Blodgett deposition and transferred at different surface pressures. The topography of the supported bilayers in aqueous solution, as imaged by AFM, revealed an increasing number of defects in the supported lipid membranes with decreased deposition pressure of the outer lipid layer. These defects, which appeared in the form of monolayer and bilayer (self-assembled) thick holes within the membrane, were energetically favorable over an evenly depleted bilayer. We found that the quantity of these defects (holes of </=0.5 micro m diameter and covering up to 30% of the surface area) correlated well with the stability of the bilayers as measured by SFA, a truly complementary instrument.
利用原子力显微镜（AFM）和表面力仪（SFA）对磷脂双层进行了研究。通过AFM测量膜形貌中的不规则程度以及通过SFA中半融合现象的出现来描述支撑双层的稳定性，半融合现象是双层膜缺陷的一个指标。通过Langmuir-Blodgett沉积法制备了由在两个叶层中具有相同头部基团但不同链长的脂质组成的双层膜，并在不同的表面压力下进行转移。通过AFM成像观察到，在水溶液中支撑双层膜的形貌显示，随着外层脂质层沉积压力的降低，支撑脂质膜中的缺陷数量增加。这些缺陷以膜内单层和双层（自组装）厚孔的形式出现，在能量上比均匀耗尽的双层更有利。我们发现，这些缺陷的数量（直径≤0.5μm且覆盖面积达30%的孔）与通过SFA测量的双层膜稳定性密切相关，SFA是一种真正具有互补性的仪器。
