中文摘要：

利用界面Langmuir单层膜和大单层囊泡的双层膜研究了不同含量胆固醇对饱和磷脂DPPC膜的影响,以及胆固醇与DPPC的相互作用。在双层膜模型中,使用DPH荧光探针标记膜,通过测量荧光稳态各向异性和荧光寿命,来探讨胆固醇对饱和DPPC双层膜流动性及微粘度的影响。在界面单层模型中,通过压力-面积曲线分析胆固醇对单层膜相变的影响,并计算吉布斯自由能实验值,与维里物态方程拟合得到理论参数相结合,讨论胆固醇与DPPC在膜上的相互作用。结果发现：加入少量胆固醇后,两种模型膜流动性降低,微粘度增大;胆固醇较高时,膜流动性转为增大,微粘度降低。当胆固醇摩尔比大于等于0.5时,流动性达到稳定。流动性的改变与胆固醇影响膜的相变过程有关,胆固醇分子和DPPC分子相互作用力的引力在胆固醇摩尔比为0.5时达到最大。

英文摘要：

The bilayer membranes of liposome and Langmuir monolayer were employed to study the interaction of cholesterol and DPPC.The effect of cholesterol on the membrane fluidity of saturated DPPC liposome has been studied by measuring the fluorescence anisotropy and lifetime of the DPH probe labelled in the liposomes.Phase transition and the intermolecular interaction have been investigated by the Langmuir technique and theoretical analysis.The results show that the fluidity of the membrane decreased first and then increased as the increase of cholesterol.While xChol≥0.5,the fluidity reached stable.The cholesterol has an influence on the phase transition of DPPC monolayer. The interaction between cholesterol and DPPC shows an attraction and reaches a maximum when xChol=0.5.