Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
Soft Matter. 2018 Feb 21;14(8):1397-1407. doi: 10.1039/c7sm02326j.
Shape transformations of flat bilayer membranes and vesicles induced by hydrolysis and condensation reactions of amphiphilic molecules are studied using coarse-grained molecular dynamics simulations. The hydrolysis and condensation reactions result in the formation and dissociation of amphiphilic molecules, respectively. Asymmetric reactions between the inner and outer leaflets of a vesicle can transport amphiphilic molecules between the leaflets. It is found that the resulting area difference between the two leaflets induces bilayer sheet protrusion (BP) and budding at low reduced volumes of the vesicles, whereas BP only occurs at high reduced volumes. The probabilities of these two types of transformations depend on the shear viscosity of the surrounding fluids compared to the membrane as well as the reaction rates. A higher surrounding fluid viscosity leads to more BP formation. The inhomogeneous spatial distribution of the hydrophobic reaction products forms the nuclei of BP formation, and faster diffusion of the products enhances BP formation. Our results suggest that adjustment of the viscosity is important to control membrane shape transformations in experiments.
采用粗粒化分子动力学模拟研究了两亲分子的水解和缩合反应诱导的平面双层膜和囊泡的形状转变。水解和缩合反应分别导致两亲分子的形成和解离。囊泡内外叶之间的不对称反应可以在叶层之间运输两亲分子。研究发现，两叶之间产生的面积差导致低还原体积下双层片突（BP）和出芽，而高还原体积下仅发生 BP。这两种转化的概率取决于与膜相比周围流体的剪切粘度以及反应速率。较高的周围流体粘度导致更多的 BP 形成。疏水性反应产物的不均匀空间分布形成 BP 形成的核，产物的更快扩散增强了 BP 的形成。我们的结果表明，在实验中调整粘度对于控制膜形状转变很重要。
