表面修饰富勒烯的聚酰胺-胺树枝状分子与生物膜的相互作用研究

采用粗粒化的分子动力学模拟,研究了末端修饰富勒烯(C60)的聚酰胺-胺(PAMAM)树枝状分子在水溶液中的结构变化以及其与磷脂膜相互作用行为.发现修饰后的PAMAM分子大小随嫁接数目的增多而减小,而形状变化并不明显,分子仍是近球形结构;同时发现C60分子因疏水作用聚集在一起.与膜作用后,因C60分子插入到双层膜内,导致分子由球形稍微向椭球形改变,分子大小也稍微增大.同时发现PAMAM分子紧紧分布在磷脂膜表面,局域膜厚度变小.     

柔性棘轮在活性粒子浴内的自发定向转动

活性物质在自然界中广泛存在.利用二维布朗动力学模拟方法,设计了一种柔性边界棘轮,并研究了其在活性粒子浴内的动力学行为.发现棘轮在活性粒子浴内能够发生定向转动,这是因为活性粒子在柔性边界周围的不均匀分布导致压力的不均匀分布,进而对棘轮产生扭矩.进一步研究了影响转动速率的因素,发现平均转动角速度随活性粒子驱动力、活性粒子密度的增大而增大,随粒子旋转扩散系数、支架数的增大而降低.研究结果对于设计新的实验系统来研究此类非平衡物理现象具有一定的指导意义.     

Anomalous boundary deformation induced by enclosed active particles

We simulate a two-dimensional model of a round soft boundary enclosed with self-propelled particles. Persistent motion drives these particles to accumulate near the boundary, thereby dramatically deforming the boundary shape through collisions. Quantitative analyses of the boundary shape and the particle distribution show that there are two typical regimes in the variation of the morphology with the increase of self-propulsion of particles. One is under small forces, characterized by the radially inhomogeneous distribution of particles and the suppression of local fluctuations of the almost round boundary, and the other is under large forces, featured by the angularly inhomogeneous distribution of particles and the global shape deformation of the boundary. These two features are strongly cooperative. We also find different mechanisms in the particle relocation at low and high particle concentrations.