论文标题
在肌动蛋白网络中示踪剂颗粒的动力学中测量的不同异常扩散状态
Different anomalous diffusion regimes measured in the dynamics of tracer particles in actin networks
论文作者
论文摘要
以前认为，示踪剂在粘弹性材料中的扩散应为分数布朗运动（FBM）类型。这是由于此类材料对机械扰动的响应的长期记忆。令人惊讶的是，发现示踪剂粒子在纯化蛋白质肌动蛋白网络中的扩散符合一项集中于集成平均特征的一项研究中的连续时间随机步行（CTRW）类型。在这里，我们分析了不同网格尺寸的肌动蛋白网络中两个不同尺寸的示踪剂颗粒的动力学。我们发现，示踪剂粒度与生物聚合物网络的特征长度尺度的比率在确定粒子执行的扩散类型方面起着至关重要的作用。我们发现，当粒子与网格尺寸相比，当粒子比网格大小小得多，并且在这两个限制之间的ctrw时，示踪粒子扩散具有FBM的特征。根据我们的发现，我们在数值上提出并验证了在所有制度中示踪剂粒子运动的新模型。我们的模型表明，肌动蛋白网络中的扩散由示踪剂粒子的FBM和偶尔的笼子事件和幂律分配的逃生时间组成。
It was previously believed that diffusion of a tracer particle in a viscoelastic material should be of the fractional Brownian motion (fBm) type. This is due to the long-term memory in the response of such materials to mechanical perturbations. Surprisingly, the diffusion of a tracer particle in a network of a purified protein, actin, was found to conform to the continuous time random walk (CTRW) type in one study that focused on the ensemble average characteristics. Here, we analyze the dynamics of two differently sized tracer particles in actin networks of different mesh sizes. We find that the ratio of tracer particle size to the characteristic length scale of a bio-polymer network plays a crucial role in determining the type of diffusion the particle performs. We find that the tracer particle diffusion has features of fBm when the particle is large compared to the mesh size, of normal diffusion when the particle is much smaller than the mesh size, and of CTRW in between these two limits. Based on our findings, we propose and verify numerically a new model for the tracer particle's motion in all regimes. Our model suggests that diffusion in actin networks consists of fBm of the tracer particle coupled with occasional caging events with power-law-distributed escape times.
