Active assembly and transport of passive colloidal architectures

Recent experiments have demonstrated the formation of colloidal clusters in dilute bacterial suspensions and probed their emergent long-time dynamics. This clustering phenomenon is a direct consequence of enhanced colloidal diffusion and active depletion forces induced by the bacteria. We have adapted our previously developed colloid-swimmer model to study the kinetics of aggregation in collections of multiple colloids subject to short-ranged adhesive interactions and to analyze the phase behavior of the colloid-swimmer mixture. In addition, stochastic simulations are employed to estimate the effective translational and rotational diffusivities of the clusters in terms of their size and of the persistence of swimmer trajectories. We also account for the curvature in the circular trajectories of the swimming bacteria, for example E. Coli, which emerges from their interaction with solid surfaces. The long-time statistics of these colloidal aggregates exhibit slow persistent rotations, which we explain using a semi-analytical model.