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化学学报
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化学学报 ›› 2010, Vol. 68 ›› Issue (13): 1325-1330. 上一篇    下一篇

研究论文

盐浓度及磷脂分子结构对多组分带电膜弯曲刚性的影响

刘春英1,2，李莉*,1,2，邱枫2，杨玉良2   

  1. (1复旦大学分析测试中心 上海 200433)
    (2复旦大学高分子科学系 聚合物分子工程教育部重点实验室 上海 200433)
  • 投稿日期:2009-10-13 修回日期:2009-12-17 发布日期:2010-03-09
  • 通讯作者: 李莉 E-mail:liyang@fudan.edu.cn
  • 基金资助:

    国家自然科学优秀研究群体基金，国家基础研究专项基金（No.2005CB623800），国家杰出青年科学基金（No.20625413）

Effects of Salt Concentration and Structure of Lipid Molecules on the Bending Rigidity of Multi-Component Charged Membranes

Liu Chunying1,2 Li Li*,1,2 Qiu Feng2 Yang Yuliang2   

  1. (1 The Center of Analysis and Measurement, Fudan University, Shanghai 200433)
    (2 Key Laboratory of Molecular Engineering of Polymers of Ministry of Education, Department of Macromolecular Science, Fudan University, Shanghai 200433)
  • Received:2009-10-13 Revised:2009-12-17 Published:2010-03-09
  • Contact: Li LI E-mail:liyang@fudan.edu.cn

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磷脂膜弯曲刚性模量很难直接测量, 本实验用循环冻融法制备尺寸大小与膜弯曲刚性相关的熵稳定单层囊泡. 粒度仪测量发现, 囊泡尺寸随盐浓度增加呈现先剧烈减小然后缓慢增加的分段变化规律. 但当组分中含有头部带电同时尾链带有不饱和键的二油酰磷脂酰甘油酯时, 囊泡尺寸却在较大的盐浓度范围内不出现回升. 囊泡膜的负Zeta-电势绝对值均表现为先急剧减小然后趋于平稳的变化规律, 数值大小只与带电组分的含量有关. 而对直接水合法制备的多层囊泡的统计发现, 囊泡尺寸随盐浓度增加急剧减小, 随后趋于稳定值, 均不随分子组合变化而回升. 结果表明在不同的盐浓度范围里, 主导磷脂膜弯曲刚性模量的因素不同. 低盐浓度的体系, 静电屏蔽效应为主导因素; 高盐浓度的体系, 膜双电层中反离子的分布起主导作用. 磷脂分子头部与尾部的不同结构组合会影响膜双电层, 使膜的弯曲刚性不同. 多层囊泡体系中, 高盐浓度下膜的热涨落掩盖了分子结构及双电层分布差异对膜弯曲刚性的影响.

关键词: 多组分带电磷脂膜, 冻融法, Zeta-电势, 弯曲刚性, 静电屏蔽, 双电层

The mean bending modulus of bilayer is difficult to be measured directly in experiment but found relating to its bending rigidity. In this paper, the size of entropic stabilized vesicles, which were prepared by freeze-thaw cycle method, was investigated. It is observed that the diameters of these freeze-thaw vesicles decrease sharply and then gradually increase with salt concentration of hydration solution increasing. However, the sizes remain unchanging in the range of higher salt concentration when the charged component 1,2-dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) (DOPG) is added in membranes. While the Zeta potential of membranes with various compositions presents the same trend of first rapid decreasing then to be steady. On the other hand, the size of multi-lamellar vesicles, prepared by hydration directly, keeps in a constant after quick decrease as salt concentration increasing. The results indicate that the electrostatic screening and properties of electrostatic double layer of the lipid bilayer are the dominant factor in low and high salt concentrations, respectively. The structure of lipid molecules and the membrane fluctuation of multi-lamellar vesicle would influence the properties of the electrostatic double layer in high salt concentration.

Key words: multi-component charged lipid membrane, freeze-thaw method, zeta potential, bending rigidity, electrostatic screening, electrostatic double layer