Formation of Spiral-Coils among Self-Propelled Chains

TL;DR

This study investigates how the flexibility of self-propelled chains influences their clustering and spiral-coil formation, revealing conditions under which long chains fold into rotating spirals, supported by simulations and biological implications.

Contribution

It demonstrates how chain flexibility affects spiral-coil formation in self-propelled chains, linking simulation results to biological observations of bacterial behavior.

Findings

Flexible long chains form spiral-coils at various densities.

Clustering behavior varies with chain bending elasticity.

Spiral-coil formation is supported by simulation and biological data.

Abstract

We study the dynamics of self-propelled chains with the excluded volume interaction via the Brownian dynamics simulation, in which the bending elasticity of chains is varied. The changes of the bending elasticity lead to various characteristics of the clustering behavior in the short-chain-only system. When a long self-propelled chain is mixed with these short chains, it can fold into the spiral-coil, a steadily rotating spiral conformation, either at a high density of short chains or at a low density if the long chain itself is sufficiently flexible. Our results qualitatively support the speculation on that the formation of the spiral-coil in the swarm of Vibrio alginolyticus is triggered by collisions from the clusters of the shorter bacteria.