Paoluzzi Matteo, Di Leonardo Roberto, Marchetti M Cristina, Angelani Luca
Department of Physics and Syracuse Soft Matter Program, Syracuse University, Syracuse NY 13244, USA.
Dipartimento di Fisica Università Sapienza, P.le A Moro 2, 00185 Rome, Italy.
Sci Rep. 2016 Sep 28;6:34146. doi: 10.1038/srep34146.
We investigate numerically the dynamics of shape and displacement fluctuations of two-dimensional flexible vesicles filled with active particles. At low concentration most of the active particles accumulate at the boundary of the vesicle where positive particle number fluctuations are amplified by trapping, leading to the formation of pinched spots of high density, curvature and pressure. At high concentration the active particles cover the vesicle boundary almost uniformly, resulting in fairly homogeneous pressure and curvature, and nearly circular vesicle shape. The change between polarized and spherical shapes is driven by the number of active particles. The center-of-mass of the vesicle performs a persistent random walk with a long time diffusivity that is strongly enhanced for elongated active particles due to orientational correlations in their direction of propulsive motion. In our model shape-shifting induces directional sensing and the cell spontaneously migrate along the polarization direction.
我们对充满活性粒子的二维柔性囊泡的形状和位移涨落动力学进行了数值研究。在低浓度下，大多数活性粒子聚集在囊泡边界，在那里正的粒子数涨落通过捕获而被放大，导致形成高密度、高曲率和高压强的缢缩点。在高浓度下，活性粒子几乎均匀地覆盖囊泡边界，导致压力和曲率相当均匀，且囊泡形状接近圆形。极化形状和球形形状之间的变化由活性粒子的数量驱动。囊泡的质心进行持续的随机游走，具有长时间扩散率，对于细长的活性粒子，由于其推进运动方向上的取向相关性，扩散率会显著增强。在我们的模型中，形状变化会引发方向感知，并且细胞会自发地沿极化方向迁移。
