Modelling a colloidal network that can dynamically stiffen via bacterial circadian proteins, KaiABC

Biological systems have the unique ability to self-organize and generate autonomous motion and work. We investigate a colloidal network that can dynamically oscillate between crosslinked and unlinked states connected by bacterial clock proteins, KaiABC. By using Langevin dynamics, we tune properties like packing fractions, interaction forces, and crosslinking probabilities to produce desired mechanical responses. The particle bond average and bond length distributions, cluster sizes, and collective particle motion are used to assess the degree of order in the system. With spherical colloids, several orders of magnitude of separation exist between the colloid relaxation period and the crosslinker periods, producing systems that switch between more-ordered states to less-ordered-but still significantly connected-states. We are extending our model system to include rod-like colloids to mimic biological systems. Our results will establish appropriate material properties and aid in the experimental design of these smart active materials that can cycle between more-ordered and less-ordered states.