Chow Edmond, Skolnick Jeffrey
School of Computational Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332;
Center for the Study of Systems Biology, School of Biology, Georgia Institute of Technology, Atlanta, GA 30332.
Proc Natl Acad Sci U S A. 2015 Dec 1;112(48):14846-51. doi: 10.1073/pnas.1514757112. Epub 2015 Nov 16.
The motions of particles in a viscous fluid confined within a spherical cell have been simulated using Brownian and Stokesian dynamics simulations. High volume fractions mimicking the crowded interior of biological cells were used. Importantly, although confinement yields an overall slowdown in motion, the qualitative effects of motion in the interior of the cell can be effectively modeled as if the system were an infinite periodic system. However, we observe layering of particles at the cell wall due to steric interactions in the confined space. Motions of nearby particles are also strongly correlated at the cell wall, and these correlations increase when hydrodynamic interactions are modeled. Further, particles near the cell wall have a tendency to remain near the cell wall. A consequence of these effects is that the mean contact time between particles is longer at the cell wall than in the interior of the cell. These findings identify a specific way that confinement affects the interactions between particles and points to a previously unidentified mechanism that may play a role in signal transduction and other processes near the membrane of biological cells.
利用布朗动力学模拟和斯托克斯动力学模拟，对限制在球形细胞内的粘性流体中粒子的运动进行了模拟。采用了高体积分数来模拟生物细胞拥挤的内部环境。重要的是，尽管限制会使运动总体变慢，但细胞内部运动的定性效应可以有效地建模，就好像系统是一个无限周期系统一样。然而，由于受限空间中的空间相互作用，我们观察到细胞壁处存在粒子分层现象。细胞壁处附近粒子的运动也高度相关，并且在对流体动力学相互作用进行建模时，这些相关性会增加。此外，靠近细胞壁的粒子倾向于停留在细胞壁附近。这些效应的一个结果是，粒子之间的平均接触时间在细胞壁处比在细胞内部更长。这些发现确定了一种限制影响粒子间相互作用的特定方式，并指出了一种以前未被识别的机制，该机制可能在生物细胞膜附近的信号转导和其他过程中发挥作用。
