Composition and Asymmetry in Supported Membranes Formed by Vesicle Fusion

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• 作者：Hanna P. Wacklin
• 刊名：Langmuir
• 出版年：2011
• 出版时间：June 21, 2011
• 年：2011
• 卷：27
• 期：12
• 页码：7698-7707
• 全文大小：1248K
• 年卷期：v.27,no.12(June 21, 2011)
• ISSN：1520-5827

文摘

The structure and formation of supported membranes at silica surfaces by vesicle fusion was investigated by neutron reflectivity and quartz crystal microbalance (QCM-D) measurements. The structure of equimolar phospholipid mixtures of DLPC鈥揇PPC, DMPC鈥揇PPC, and DOPC鈥揇PPC depends intricately on the vesicle deposition conditions. The supported bilayer membranes exhibit varying degrees of compositional asymmetry between the monolayer leaflets, which can be modified by the deposition temperature as well as the salt concentration of the vesicle solution. The total lipid composition of the supported bilayers differs from the composition of the vesicles in solution, and the monolayer proximal to the silica surface is always enriched in DPPC compared to the distal monolayer. The results, which show unambiguougsly that some exchange and rearrangement of lipids occur during vesicle deposition, can be rationalized by considering the effects of salt screening and temperature on the rates of lipid exchange, rearrangement, and vesicle adsorption, but there is also an intricate dependence on the lipid鈥搇ipid interactions. Thus, although both symmetric and asymmetric supported bilayers can be prepared from vesicles, the optimal conditions are sensitive to the lipid composition of the system.