Bingham Richard J, Olmsted Peter D, Smye Stephen W
Polymers and Complex Fluids Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom.
Phys Rev E Stat Nonlin Soft Matter Phys. 2010 May;81(5 Pt 1):051909. doi: 10.1103/PhysRevE.81.051909. Epub 2010 May 7.
Bilayer lipid membranes (BLMs) are an essential component of all biological systems, forming a functional barrier for cells and organelles from the surrounding environment. The lipid molecules that form membranes contain both permanent and induced dipoles, and an electric field can induce the formation of pores when the transverse field is sufficiently strong (electroporation). Here, a phenomenological free energy is constructed to model the response of a BLM to a transverse static electric field. The model contains a continuum description of the membrane dipoles and a coupling between the headgroup dipoles and the membrane tilt. The membrane is found to become unstable through buckling modes, which are weakly coupled to thickness fluctuations in the membrane. The thickness fluctuations, along with the increase in interfacial area produced by membrane buckling, increase the probability of localized membrane breakdown, which may lead to pore formation. The instability is found to depend strongly on the strength of the coupling between the dipolar headgroups and the membrane tilt as well as the degree of dipolar ordering in the membrane.
双层脂质膜（BLMs）是所有生物系统的重要组成部分，为细胞和细胞器与周围环境形成功能性屏障。构成膜的脂质分子既包含永久偶极子也包含诱导偶极子，当横向电场足够强时（电穿孔），电场可诱导孔的形成。在此，构建了一个唯象自由能来模拟BLM对横向静电场的响应。该模型包含对膜偶极子的连续描述以及头基偶极子与膜倾斜之间的耦合。发现膜通过屈曲模式变得不稳定，这些模式与膜中的厚度波动弱耦合。厚度波动以及膜屈曲产生的界面面积增加，增加了局部膜破裂的概率，这可能导致孔的形成。发现这种不稳定性强烈依赖于偶极头基与膜倾斜之间的耦合强度以及膜中偶极有序度。
