Tethered Bilayer Lipid Membranes Studied by Simultaneous Attenuated Total Reflectance Infrared Spectroscopy and Electrochemical Impedance Spectroscopy

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• 作者：Andreas Erbe ; Richard J. Bushby ; Stephen D. Evans ; Lars J. C. Jeuken
• 刊名：Journal of Physical Chemistry B
• 出版年：2007
• 出版时间：April 5, 2007
• 年：2007
• 卷：111
• 期：13
• 页码：3515 - 3524
• 全文大小：301K
• 年卷期：v.111,no.13(April 5, 2007)
• ISSN：1520-5207

文摘

The formation of tethered lipid bilayer membranes (tBLMs) from unilamelar vesicles of egg yolkphosphatidylcholine (EggPC) on mixed self-assembled monolayers (SAMs) from varying ratios of 6-mercaptohexanol and EO₃Cholesteryl on gold has been monitored by simultaneous attenuated total reflectanceFourier transform infrared (ATR-FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS).The influence of the lipid orientation (and hence the anisotropy) of lipids on a gold film on the dichroic ratiowas studied by simulations of spectra with a matrix method for anisotropic layers. It is shown that for certaintilt angles of the dielectric tensor of the adsorbed anisotropic layer dispersive and negative absorption bandsare possible. The experimental data indicate that the structure of the assemblies obtained varies with varyingSAM composition. On SAMs with a high content of EO₃Cholesteryl, tBLMs with reduced fluidity are formed.For SAMs with a high content of 6-mercaptohexanol, the results are consistent with the adsorption of flattenedvesicles, and spherical vesicles have been found in a small range of surface compositions. The kinetics of theadsorption process is consistent with the assumption of spherical vesicles as long-living intermediates forsurfaces of a high 6-mercaptohexanol content. No long-living spherical vesicles have been detected for surfaceswith a large fraction of EO₃Cholesteryl tethers. The observed differences between the surfaces suggest thatfor the formation of tBLMs (unlike supported BLMs) no critical surface coverage of vesicles is needed priorto lipid bilayer formation.