Effect of Support Corrugation on Silica Xerogel−Supported Phase-Separated Lipid Bilayers

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• 作者：Emel I. Goksu^† ; ; Barbara A. Nellis^† ; ^‡ ; ; Wan-Chen Lin^§ ; ; Joe H. Satcher ; ^‡ ; ; Jay T. Groves^§ ; ; Subhash H. Ri
• 刊名：Langmuir
• 出版年：2009
• 出版时间：March 17, 2009
• 年：2009
• 卷：25
• 期：6
• 页码：3713-3717
• 全文大小：239K
• 年卷期：v.25,no.6(March 17, 2009)
• ISSN：1520-5827

文摘

Lipid bilayers supported by substrates with nanometer-scale surface corrugations hold interest in understanding both nanoparticle−membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g., porosity. Here, we successfully form a two-phase (gel−fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, lateral diffusion coefficient, and lipid density in comparison to mica-supported lipid bilayers were characterized by atomic force microscopy, fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS), and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the silica xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface in the fluid regions. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of fluid lipids on silica xerogel (1.7 μm²/s) is lower than on mica (3.9 μm²/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on silica xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase lipid bilayer that penetrates approximately midway into the first layer of 50 nm silica xerogel beads.