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arXiv 0811.2831cond-mat.soft
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脂滴形成囊泡的动力学:机制和可控性

Dynamics of Vesicle Formation from Lipid Droplet: Mechanism and Controllability

Zilu Wang, Xuehao He

摘要:

Marrink等人[J. Phys. Chem. B 111,7812(2007)]开发的粗粒模型用于研究脂质[二棕榈酰磷脂酰胆碱(DPPC)]液滴在水中的囊泡化。随着脂滴尺寸的增大,胶束呈现三种形态。当初始脂滴较小时,液滴的平衡结构为球形胶束。当初始脂滴较大时,脂质球开始转变为盘状胶束或囊泡。从分子水平上分析了DPPC自组装形成囊泡的机理,并证明了随着液滴尺寸的增大,囊泡的形态从圆盘状向囊泡状转变。重要的是,我们发现转变点不是很尖锐,并且对于固定大小的脂质球,盘和囊泡以一定的概率出现。分裂现象,即,从脂滴的盘/囊泡结构的形成,解释了通过应用混合模型的Helfrich膜理论。成功地预测了DPPC双层的弹性模量和形成囊泡所需的最小脂滴尺寸。

英文摘要:

A coarse-grained model developed by Marrink et al. [J. Phys. Chem. B 111, 7812 (2007)] is applied to investigate vesiculation of lipid [dipalmitoylphosphatidylcholine (DPPC)] droplets in water. Three kinds of morphologies of micelles are found with increasing lipid droplet size. When the initial lipid droplet is smaller, the equilibrium structure of the droplet is a spherical micelle. When the initial lipid droplet is larger, the lipid ball starts to transform into a disk micelle or vesicle. The mechanism of vesicle formation from a lipid ball is analyzed from the self-assembly of DPPC on the molecular level, and the morphological transition from disk to vesicle with increasing droplet size is demonstrated. Importantly, we discover that the transition point is not very sharp, and for a fixed-size lipid ball, the disk and vesicle appear with certain probabilities. The splitting phenomenon, i.e., the formation of a disk/vesicle structure from a lipid droplet, is explained by applying a hybrid model of the Helfrich membrane theory. The elastic module of the DPPC bilayer and the smallest size of a lipid droplet for certain formation of a vesicle are successfully predicted.

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