Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ, 08544, USA.
Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Düsseldorf, 40225, Düsseldorf, Germany.
Nat Commun. 2021 Dec 6;12(1):7088. doi: 10.1038/s41467-021-26942-0.
Efficient navigation through disordered, porous environments poses a major challenge for swimming microorganisms and future synthetic cargo-carriers. We perform Brownian dynamics simulations of active stiff polymers undergoing run-reverse dynamics, and so mimic bacterial swimming, in porous media. In accord with experiments of Escherichia coli, the polymer dynamics are characterized by trapping phases interrupted by directed hopping motion through the pores. Our findings show that the spreading of active agents in porous media can be optimized by tuning their run lengths, which we rationalize using a coarse-grained model. More significantly, we discover a geometric criterion for the optimal spreading, which emerges when their run lengths are comparable to the longest straight path available in the porous medium. Our criterion unifies results for porous media with disparate pore sizes and shapes and for run-and-tumble polymers. It thus provides a fundamental principle for optimal transport of active agents in densely-packed biological and environmental settings.
高效穿越无序多孔环境是游泳微生物和未来合成货物载体面临的主要挑战。我们在多孔介质中进行了经历奔跑-反转动力学的活性刚性聚合物的布朗动力学模拟，从而模拟了细菌的游动。与大肠杆菌的实验一致，聚合物动力学的特征是被通过孔的定向跳跃运动打断的捕获相。我们的研究结果表明，可以通过调整活性物质的奔跑长度来优化它们在多孔介质中的扩散，我们使用粗粒化模型对此进行了合理化解释。更重要的是，我们发现了一个最优扩散的几何判据，当它们的奔跑长度与多孔介质中可用的最长直线路径相当时，这个判据就会出现。我们的判据统一了具有不同孔径和形状的多孔介质以及奔跑-翻转聚合物的结果。因此，它为在密集的生物和环境环境中优化活性物质的输运提供了一个基本原理。
