The effect of different cholesterol （Chol）-content on the mixed monolayer of the phosphati- dylethanolamine （PE）/phosphatidylcholine （PC） （1 ： 1 molar ratio） has been investigated by analyzing the surface pressure-area isotherms. And the thermodynamic behavior of mixed monolayer of Chol and PE/PC （1 ＇ I molar ratio） has been investigated by calculating and analyzing the excess molecular area and excess Gibbs energy （AAex and AGex）. The results show that Chol accelerated the phase transition and promoted the aggregation of monolayer. When Xchol-~0.2, 0.6, 0.8, AAex and AGe~ displayed negative values, suggesting attractive interaction between molecules. While XChol=0.4, △Aex and △Gex displayed positive values at the surface pressure of 15, 20, 25, 30 mN/m, indicating repelling interaction between molecules, promoting the increasing of the entropy. In addition, the deposited Langmuir-Blodgett （LB） monolayers of different ratios were investigated with atomic force microscoov （AFM）.%研究了不同比例下胆固醇（Chol）对磷脂酰乙醇胺/磷脂酰胆碱（PE/PC,1∶1物质的量比）混合膜的影响,并在表面压力-平均分子面积（π-A曲线）等温线基础上,通过对过量平均分子面积（ΔAex）和过量吉布斯自由能（ΔGex）的计算分析,研究了不同比例Chol与PE/PC（1∶1物质的量比）三元混合膜的热力学特性.实验结果表明：Chol在一定程度上加速了混合膜的相变,增强了膜的凝聚性;当XChol=0.2,0.6,0.8时,过量平均分子面积和过量吉布斯自由能在所研究的表面压力下都为负值,分子之间相互作用力表现为引力,促使混合膜的凝聚,而在XChol=0.4时,过量平均分子面积和过量吉布斯自由能在15,20,25,30 mN/m下为正值,分子之间相互作用力表现为斥力,促使熵的增加,并且在20 mN/m压力下出现极值.实验中利用LB膜技术制备了不同比例Chol与PE/PC（1∶1物质的量比）混合膜,并在原子力显微镜下对其结构形态进行了观测.
展开▼
