McGregor M A, Barnes G T
J Pharm Sci. 1978 Aug;67(8):1054-6. doi: 10.1002/jps.2600670808.
Equilibrium surface pressure-area isotherms for the penetration of cholesterol monolayers by the surfactant cetrimonium bromide are presented. From these isotherms, the saturation adsorptions of surfactant for various surface concentrations of cholesterol were calculated. Plots of adsorption against the inverse of the area per cholesterol molecule revealed two linear revealed two linear regions, corresponding to penetration at high and low monolayer areas. At high monolayer areas, surfactant adsorption into accessible areas of the surface was similar to adsorption at a monolayer-free surface. In this region, packing of cholesterol and surfactant molecules on the surface lowered the effective cross-sectional area of the cholesterol molecule. However, at low monolayer areas, adsorption was determined by the size of the surfactant ion and the effective area of the cholesterol molecule was equal to the collapse area of a pure cholesterol monolayer.
给出了表面活性剂溴化十六烷基三甲基铵穿透胆固醇单分子层的平衡表面压力-面积等温线。根据这些等温线，计算了不同胆固醇表面浓度下表面活性剂的饱和吸附量。以吸附量对每个胆固醇分子的面积的倒数作图，显示出两个线性区域，分别对应于高单分子层面积和低单分子层面积时的穿透情况。在高单分子层面积时，表面活性剂吸附到表面的可及区域与在无单分子层表面的吸附情况相似。在该区域，胆固醇和表面活性剂分子在表面的堆积降低了胆固醇分子的有效横截面积。然而，在低单分子层面积时，吸附由表面活性剂离子的大小决定，且胆固醇分子的有效面积等于纯胆固醇单分子层的塌陷面积。
