Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana, Illinois 61801, USA.
1] Department of Materials Science, University of Illinois, Urbana, Illinois 61801, USA [2] Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, USA.
Nat Mater. 2015 Jun;14(6):589-93. doi: 10.1038/nmat4239. Epub 2015 Mar 30.
In contrast to Brownian transport, the active motility of microbes, cells, animals and even humans often follows another random process known as truncated Lévy walk. These stochastic motions are characterized by clustered small steps and intermittent longer jumps that often extend towards the size of the entire system. As there are repeated suggestions, although disagreement, that Lévy walks have functional advantages over Brownian motion in random searching and transport kinetics, their intentional engineering into active materials could be useful. Here, we show experimentally in the classic active matter system of intracellular trafficking that Brownian-like steps self-organize into truncated Lévy walks through an apparent time-independent positive feedback such that directional persistence increases with the distance travelled persistently. A molecular model that allows the maximum output of the active propelling forces to fluctuate slowly fits the experiments quantitatively. Our findings offer design principles for programming efficient transport in active materials.
与布朗运动相反，微生物、细胞、动物甚至人类的主动运动通常遵循另一种称为截断 Lévy 游走的随机过程。这些随机运动的特点是小步聚集和间歇性的大步跳跃，这些跳跃通常延伸到整个系统的大小。尽管存在分歧，但有很多建议认为，Lévy 游走在随机搜索和输运动力学方面比布朗运动具有功能优势，因此将其有意设计到主动材料中可能会很有用。在这里，我们在经典的细胞内运输主动物质系统中通过明显的时间独立正反馈实验表明，布朗尼样步自组织成截断 Lévy 游走，从而方向持续性随着持续行进的距离而持续增加。一个允许主动推进力的最大输出缓慢波动的分子模型定量地符合实验。我们的发现为主动材料中有效输运的编程提供了设计原则。
