Molecular dynamics simulation of rupture of lipid bilayer under dynamic surface tension

doi:10.11949/j.issn.0438-1157.20151147

Abstract

Abstract:

The biocompatible nature of lipid bilayer makes it appealing for wide applications including biosensor, biomimetic membrane for separation or reaction. Understanding lipid bilayer rupture is of fundamental importance for the design and application of lipid bilayer based devices. In the present study, a lipid bilayer membrane made by dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphoglycerol (DPPG) was used for the molecular dynamics simulation of the lipid bilayer rupture. A method for determining the rupture time and the critical surface tension was proposed, based on which, the effects of lipid bilayer composition on the lipid bilayer rupture were examined. It was shown that an increase in the negatively charged DPPG in the lipid bilayer postponed the rupture time, indicating a strengthened structural stability. On the other hand, the widened distribution of the rupture time indicated the heterogeneous nature of the lipid bilayer. A dynamic microscopic opposing forces model was proposed to describe the above mentioned lipid bilayer rupture under an unsteady surface tension. The model had reproduced the simulation results and thus offered theoretical tools for the design and optimization of the lipid bilayer based devices and processes.

Key words: DPPC/DPPG lipid bilayer membrane, molecular simulation, lipid bilayer rupture, surface tension, kinetic theory

摘要：

磷脂双层膜在生物传感器、仿生膜和生物膜反应器等领域具有广阔的应用前景。揭示磷脂膜破裂过程规律对于磷脂膜器件设计和应用具有重要的基础意义。以二棕榈酰磷脂酰胆碱(dipalmitoyl phosphatidylcholine, DPPC)和二棕榈酰磷脂酰甘油(dipalmitoyl phosphoglycerol, DPPG)作为磷脂膜组分,采用粗粒化分子动力学模拟研究了磷脂膜组成对其破裂过程的影响规律。首先建立了磷脂膜破裂动力学的临界破裂时间及临界破裂表面张力的识别方法;进而考察了磷脂膜组成对其破裂动力学的影响规律。模拟结果表明随着带负电组分DPPG 含量增加,磷脂膜平均临界破裂时间延迟且分布变宽,即磷脂膜强度提高,磷脂膜破裂呈现非均匀特性。提出了描述动态表面张力作用下磷脂膜破裂过程的"动态"微观对抗理论,由该理论可预期磷脂膜的线张力随着DPPG 含量提高而增强,与分子动力学模拟结果相符。为基于磷脂膜的分子器件的设计提供了数值模拟及理论依据。

关键词: DPPC/DPPG 磷脂双层膜, 分子模拟, 磷脂膜破裂, 表面张力, 动力学理论

CLC Number:

TQ021.4

KONG Xian, HU Xiaoyu, LU Diannan, LIU Zheng. Molecular dynamics simulation of rupture of lipid bilayer under dynamic surface tension[J]. CIESC Journal, 2016, 67(2): 641-647.

孔宪, 胡晓宇, 卢滇楠, 刘铮. 动态表面张力破裂磷脂膜的分子动力学模拟[J]. 化工学报, 2016, 67(2): 641-647.

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