Probing microscopic origins of confined subdiffusion by first-passage observables
Probing microscopic origins of confined subdiffusion by first-passage observables
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DOI：
10.1073/pnas.0712158105
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发表时间：
2008-04-15
影响因子：
11.1
通讯作者：
Klafter, J.
中科院分区：
文献类型：
--
作者：
Condamin, S.;Tejedor, V.;Klafter, J.
示踪粒子在生物细胞等复杂拥挤环境中的亚扩散运动已被证明是普遍存在的。这种与布朗运动的偏差通常由均方位移(MSD)的亚线性时间依赖关系来表征。然而，次扩散行为可能源于不同的微观场景，而这些场景不能仅由MSD数据来识别。在这篇文章中，我们提出了一个理论框架，它允许解析计算任何维度无序介质中的首次通过可观测参数(平均首次通过时间、分裂概率和占据时间分布)。这一分析被应用于两个具有代表性的次扩散的微观模型：具有重尾等待时间的连续时间随机游动和基于分形的扩散。我们的结果表明，首次通过观测提供了明确区分两种可能的次扩散微观情景的工具。此外，我们建议进行基于首次通过观测的实验，这些实验可以帮助确定复杂介质(如活细胞)中次扩散的来源，并讨论异常传输对细胞中反应动力学的影响。
Subdiffusive motion of tracer particles in complex crowded environments, such as biological cells, has been shown to be widespread. This deviation from Brownian motion is usually characterized by a sub-linear time dependence of the mean square displacement (MSD). However, subdiffusive behavior can stem from different microscopic scenarios that cannot be identified solely by the MSD data. In this article we present a theoretical framework that permits the analytical calculation of first-passage observables (mean first-passage times, splitting probabilities, and occupation times distributions) in disordered media in any dimensions. This analysis is applied to two representative microscopic models of subdiffusion: continuous-time random walks with heavy tailed waiting times and diffusion on fractals. Our results show that first-passage observables provide tools to unambiguously discriminate between the two possible microscopic scenarios of subdiffusion. Moreover, we suggest experiments based on first-passage observables that could help in determining the origin of subdiffusion in complex media, such as living cells, and discuss the implications of anomalous transport to reaction kinetics in cells.