Asgari Meisam, Biria Aisa
Department of Mechanical Engineering, McGill University, Montréal, QC H3A 0C3, Canada.
Int J Non Linear Mech. 2015 Nov;76:135-143. doi: 10.1016/j.ijnonlinmec.2015.06.001.
Lipid-bilayers are the fundamental constituents of the walls of most living cells and lipid vesicles, giving them shape and compartment. The formation and growing of pores in a lipid bilayer have attracted considerable attention from an energetic point of view in recent years. Such pores permit targeted delivery of drugs and genes to the cell, and regulate the concentration of various molecules within the cell. The formation of such pores is caused by various reasons such as changes in cell environment, mechanical stress or thermal fluctuations. Understanding the energy and elastic behaviour of a lipid-bilayer edge is crucial for controlling the formation and growth of such pores. In the present work, the interactions in the molecular level are used to obtain the free energy of the edge of an open lipid bilayer. The resulted free-energy density includes terms associated with flexural and torsional energies of the edge, in addition to a line-tension contribution. The line tension, elastic moduli, and spontaneous normal and geodesic curvatures of the edge are obtained as functions of molecular distribution, molecular dimensions, cutoff distance, and the interaction strength. These parameters are further analyzed by implementing a soft-core interaction potential in the microphysical model. The dependence of the elastic free-energy of the edge to the size of the pore is reinvestigated through an illustrative example, and the results are found to be in agreement with the previous observations.
脂质双层是大多数活细胞和脂质囊泡壁的基本组成部分，赋予它们形状和分隔空间。近年来，从能量角度来看，脂质双层中孔的形成和生长引起了相当大的关注。这种孔允许将药物和基因靶向递送至细胞，并调节细胞内各种分子的浓度。这种孔的形成是由多种原因引起的，如细胞环境变化、机械应力或热涨落。了解脂质双层边缘的能量和弹性行为对于控制此类孔的形成和生长至关重要。在本工作中，利用分子水平的相互作用来获得开放脂质双层边缘的自由能。所得的自由能密度除了线张力贡献外，还包括与边缘的弯曲和扭转能量相关的项。边缘的线张力、弹性模量以及自发法向曲率和测地曲率作为分子分布、分子尺寸、截止距离和相互作用强度的函数而获得。通过在微观物理模型中实施软核相互作用势，对这些参数进行了进一步分析。通过一个示例重新研究了边缘弹性自由能对孔尺寸的依赖性，结果发现与先前的观察结果一致。
