Williamson J J, Olmsted P D
Department of Physics, Institute for Soft Matter Synthesis and Metrology, Georgetown University, 37th and O Streets, N.W., Washington, D.C. 20057, USA.
Soft Matter. 2015 Dec 14;11(46):8948-59. doi: 10.1039/c5sm01328c. Epub 2015 Sep 28.
We study the kinetics governing the attainment of inter-leaflet domain symmetry in a phase-separating amphiphilic bilayer. "Indirect" inter-leaflet coupling via hydrophobic mismatch can induce an instability towards a metastable pattern of locally asymmetric domains upon quenching from high temperature. This necessitates a nucleation step to form the conventional symmetric domains, which are favoured by a "direct" inter-leaflet coupling. We model the energetics for a symmetric domain to nucleate from the metastable state, and find that an interplay between hydrophobic mismatch and thickness stretching/compression causes the effective hydrophobic mismatch, and thus line tension, to depend on domain size. This leads to strong departure from classical nucleation theory. We speculate on implications for cell membrane rafts or clusters, whose size may be of similar magnitude to estimated critical radii for domain symmetry.
我们研究了在相分离两亲性双层膜中控制叶间区域对称性实现的动力学。通过疏水失配的“间接”叶间耦合在从高温淬火时会导致对局部不对称区域的亚稳模式产生不稳定性。这就需要一个成核步骤来形成传统的对称区域，而“直接”叶间耦合有利于这种对称区域的形成。我们对对称区域从亚稳态成核的能量学进行了建模，发现疏水失配与厚度拉伸/压缩之间的相互作用导致有效疏水失配，进而导致线张力取决于区域大小。这导致与经典成核理论有很大偏差。我们推测了其对细胞膜筏或簇的影响，其大小可能与估计的区域对称临界半径相似。
