Nakahara Hiromichi, Nakamura Shohei, Nakamura Kazufumi, Inagaki Masanori, Aso Mariko, Higuchi Ryuichi, Shibata Osamu
Division of Biointerfacial Science, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Colloids Surf B Biointerfaces. 2005 May 10;42(2):175-85. doi: 10.1016/j.colsurfb.2005.01.013.
Two-component Langmuir monolayers formed on a subphase of 0.5M sodium chloride solution were investigated for two different cerebrosides (LMC-1 and LMC-2) with steroids of cholesterol (Ch) and cholesteryl sodium sulfate (Ch-S); i.e. LMC-1/Ch, LMC-1/Ch-S, LMC-2/Ch, and LMC-2/Ch-S were examined in terms of surface pressure (pi), the surface potential (DeltaV) and the dipole moment (mu( perpendicular)) as a function of surface area (A) by employing the Langmuir method, the ionizing electrode method, and the fluorescence microscopy. Surface potentials (DeltaV) of steroids were analyzed using the three-layer model proposed by Demchak and Fort. The miscibility of cerebrosides and steroids in the insoluble monolayers was examined by plotting the variation of the molecular area and the surface potential as a function of the steroid molar fraction (X(steroid)) based upon the additivity rule. From the A-X(steroid) and DeltaV(m)-X(steroid) plots, partial molecular surface area (PMA) and apparent partial molecular surface potential (APSP) were determined at the different surface pressures. The PMA and APSP with the mole fraction were discussed for the miscible system. Judging from the two-dimensional phase diagrams, they can be classified into two types. The first is a completely immiscible type; the combination of cerebrosides with cholesterol. The second is a negative azeotropic type, where cerebrosides and cholesteryl sodium sulfate are completely miscible both in the expanded state and in the condensed state. In addition, a regular surface mixture (the Joos equation for the analysis of the collapse pressure of two-component monolayers) allowed calculation of the interaction parameter (xi) and the interaction energy (-Delta epsilon) between the cerebrosides and Ch-S. The miscibility of cerebroside and steroid components in the monolayer state was also supported by fluorescence microscopy.
研究了在0.5M氯化钠溶液亚相上形成的双组分朗缪尔单分子层，涉及两种不同的脑苷脂（LMC - 1和LMC - 2）与胆固醇（Ch）和胆固醇硫酸钠（Ch - S）等类固醇；即通过朗缪尔方法、电离电极法和荧光显微镜，研究了LMC - 1/Ch、LMC - 1/Ch - S、LMC - 2/Ch和LMC - 2/Ch - S的表面压力（π）、表面电位（ΔV）和偶极矩（μ(⊥)）随表面积（A）的变化。使用Demchak和Fort提出的三层模型分析类固醇的表面电位（ΔV）。根据加和规则，通过绘制分子面积和表面电位随类固醇摩尔分数（X(类固醇)）的变化图，研究了不溶性单分子层中脑苷脂和类固醇的混溶性。从A - X(类固醇)和ΔV(m) - X(类固醇)图中，确定了不同表面压力下的部分分子表面积（PMA）和表观部分分子表面电位（APSP）。讨论了混溶体系中PMA和APSP与摩尔分数的关系。从二维相图判断，它们可分为两种类型。第一种是完全不混溶型，即脑苷脂与胆固醇的组合。第二种是负共沸型，其中脑苷脂和胆固醇硫酸钠在膨胀态和凝聚态下都完全混溶。此外，一个规则的表面混合物（用于分析双组分单分子层崩溃压力的乔斯方程）允许计算脑苷脂和Ch - S之间的相互作用参数（ξ）和相互作用能（-Δε）。荧光显微镜也证实了单分子层状态下脑苷脂和类固醇组分的混溶性。
