Physics Department, University of California, Merced, CA 95343, USA.
Proc Natl Acad Sci U S A. 2013 Feb 26;110(9):3242-7. doi: 10.1073/pnas.1213994110. Epub 2013 Feb 11.
Complex morphologies in lipid membranes typically arise due to chemical heterogeneity, but in the tilted gel phase, complex shapes can form spontaneously even in a membrane containing only a single lipid component. We explore this phenomenon via experiments and coarse-grained simulations on giant unilamellar vesicles of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine. When cooled from the untilted L(α) liquid-crystalline phase into the tilted gel phase, vesicles deform from smooth spheres to disordered, highly crumpled shapes. We propose that this shape evolution is driven by nucleation of complex membrane microstructure with topological defects in the tilt orientation that induce nonuniform membrane curvature. Coarse-grained simulations demonstrate this mechanism and show that kinetic competition between curvature change and defect motion can trap vesicles in deeply metastable, defect-rich structures.
脂质膜中的复杂形态通常是由于化学异质性引起的，但在倾斜凝胶相中，即使在仅含有单个脂质成分的膜中，复杂形状也可以自发形成。我们通过对 1,2-二棕榈酰-sn-甘油-3-磷酸胆碱的巨大单层囊泡的实验和粗粒度模拟来探索这一现象。当从未倾斜的 L(α)液晶相冷却到倾斜的凝胶相时，囊泡从光滑的球体变形为无序的、高度褶皱的形状。我们提出，这种形状演化是由在倾斜方向上具有拓扑缺陷的复杂膜微观结构的成核驱动的，这些缺陷会引起非均匀的膜曲率。粗粒度模拟证明了这种机制，并表明曲率变化和缺陷运动之间的动力学竞争可以将囊泡困在深度亚稳、缺陷丰富的结构中。
