生长、屈曲与涡旋：聚合作用产生的运动性
Growing, Buckling, and Swirling: motility from polymerization
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中文总结 AI 辅助
研究低雷诺数环境中表面锚定细丝生长聚合产生的运动性问题，构建连续介质框架，分析表明聚合诱导压缩力致屈曲不稳定性，耦合框架与粒子得出多种运动行为，为该运动性建立理论基础并指出合成游泳者设计原则。
中文摘要 AI 辅助
在低雷诺数环境中的运动通过多种显著策略实现，从鞭毛旋转、纤毛摆动到大规模身体变形。当表面锚定的细丝生长并集体重新定向时会产生一类独特且具有生物学重要性的推进方式，如在木醋杆菌和受单核细胞增生李斯特氏菌运动启发的肌动蛋白驱动合成胶体实验中所见，这表明聚合本身是自我推进的一般途径。为此我们构建了一个连续介质框架，其中驱动运动的主动力从细丝成核、生长、灾变和流体动力相互作用中自洽地产生。通过分析表明聚合诱导的压缩力驱动长波长屈曲不稳定性，导致细丝地毯的自发对称性破缺和大规模流动。将此框架与无外力和无扭矩的运动性球体粒子耦合，出现了多种行为，包括自发旋转、定向运动和手性游动，其选择由聚合细丝的空间图案控制。这些结果为聚合细丝的集体动力学驱动的运动性建立了一般理论基础，并指出了合成微米级游泳者的新设计原则。
英文摘要
Locomotion in low-Reynolds-number environments is achieved through a remarkable diversity of strategies, from flagellar rotation and ciliary beating to large-scale body deformations. A distinct and biologically important class of propulsion arises when surface-anchored filaments grow and collectively reorient - as seen in the cellulose-extruding bacterium Acetobacter xylinum and in recent experiments on actin-propelled synthetic colloids inspired by the motility of Listeria monocytogenes - suggesting that polymerization itself is a generic route to self-propulsion. Developing a theoretical framework for this class of problems requires simultaneously resolving filament kinetics, their orientational dynamics, and fluid-structure interactions - all self-consistently coupled to the resulting locomotion. To address this, we formulate a continuum framework in which the active forces driving locomotion emerge self-consistently from filament nucleation, growth, catastrophe, and hydrodynamic interactions. We show analytically that polymerization-induced compressive forces drive a long-wavelength buckling instability, leading to spontaneous symmetry breaking of the filament carpet and large-scale flows. In coupling this framework to a force- and torque-free motile spheroidal particle, a wide variety of behaviors emerge - this includes spontaneous spinning, directed motility, and chiral swimming - whose selection is governed by the spatial patterning of polymerizing filaments. These results establish a general theoretical foundation for motility, driven by collective dynamics of polymerizing filaments and point towards new design principles for synthetic micron-scale swimmers.
