Electrostatic interactions in phospholipid membranes I: Influence of monovalent ions
Electrostatic interactions in phospholipid membranes I: Influence of monovalent ions
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磷脂膜中的静电相互作用 I：单价离子的影响
DOI：
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发表时间：
1986
期刊：
影响因子：
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通讯作者：
Helmuth Möhwald
中科院分区：
文献类型：
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作者：
Christiane A. Helm;L. Laxhuber;Mathias Lösche;Helmuth Möhwald
本文用光学和化学技术结合数值计算研究了酸性磷脂单分子膜和囊泡中的静电相互作用。一个非单调的离子强度依赖与极值在0.1 M（NaCl）的囊泡的相变温度，以及在低分子密度的单层的表面压力观察。这一发现与预测单价反离子仅在浓度高于0.1 M时电荷屏蔽占主导地位的计算结果一致。然而，对于较低的盐含量，其增加导致解离度的升高，从而也导致静电排斥。这导致更高的表面压力，较低的转变温度和较小的尺寸的固体域中观察到的液/固共存范围的单分子膜。这支持了先前发表的观点，即有限的尺寸和排斥的域产生于不同的表面电荷密度在流体和固体脂质相。
Electrostatic interactions in monolayers and vesicles of acidic phospholipids are studied by thermodynamical and optical techniques in conjunction with numerical calculations. A nonmonotonic ionic strength dependence with an extremum at 0.1 M (NaCl) is observed for the phase transition temperature of vesicles as well as for the surface pressure of monolayers at low molecular density. This finding is in accordance with the calculations predicting the dominance of charge screening by monovalent counterions only for concentrations above 0.1 M. For lower salt content, however, its increase causes an elevation of the degree of dissociation and thus also electrostatic repulsion. This leads to a higher surface pressure, a lower transition temperature and a smaller size of solid domains observed in the liquid/solid coexistence range of monolayers. This supports the previously published idea, that finite size and repulsion of the domains arise from a different surface charge density in fluid and solid lipid phases.