关键词: 原位偏振红外反射光谱, 金（111）电极, 浮动磷脂双层膜

Abstract: In situ Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was used to study the structure of a DMPC + cholesterol + GM1 floating bilayer lipid membrane (fBLM) at a Au(111) surface. 1-thio-beta-D-glucose (beta-Tg) was self-assembled onto the Au electrode to increase the overall hydrophilicity of the surface. The fBLM was deposited on the beta-Tg self-assembled monolayer (SAM) using a combination of Langmuir-Blodgett/Langmuir-Schaefer (LB/LS) techniques. The carbohydrate headgroups of the GM1 molecules were physically adsorbed to the beta-Tg SAM forming a water rich cushion between the fBLM and the modified gold substrate. The PM-IRRAS spectra indicate that the DMPC molecules within the fBLM are more hydrated than previous studies involving supported bilayer lipid membranes (sBLM) where the membrane is directly adsorbed onto the surface. The tilt angle of the DMPC acyl chains in the fBLM is smaller than that of the sBLM composed of similar components. The results from this work confirmed that the fBLM is stable over a wide range of electrode potentials and that a water rich region is present between the bilayer and gold electrode surface. The addition of this water region more closely mimics the natural environment of a biological membrane making the fBLM a desirable candidate for future in situ studies involving transmembrane proteins.

Key words: PM-IRRAS, floating bilayer lipid membrane, Au(111) electrode, water rich region