Self-Assembled Revolving Rings of Reversibly Catenated Active Colloids

Synthetic self-assembly remains rudimentary compared to biological systems, often constrained by equilibrium thermodynamics. We present a nonequilibrium strategy for the topological engineering of assemblies using self-propelled Janus particles. These active components hierarchically form revolving rings─self-limiting structures guided by anisotropic forces and torques. We identify a "self-biting" closure mechanism arising from competing directional attraction and lateral repulsion, leading to nonmonotonic growth dynamics. Molecular dynamics simulations highlight the essential role chain flexibility plays in ring formation. Our findings reveal how activity and anisotropic interactions can be harnessed to create dynamically stable, topologically complex assemblies for autonomous micromachines.