We report an autonomous oscillatory micromotor system in which active colloidal particles form clusters, the size of which changes periodically. The system consists of an aqueous suspension of silver orthophosphate microparticles under UV illumination, in the presence of varying concentrations of hydrogen peroxide. The colloid particles first attract each other to form clusters. After a short delay, these clusters abruptly disperse and oscillation begins, alternating between clustering and dispersion of particles. After a cluster oscillation initiates, the oscillatory wave propagates to nearby clusters and eventually all the clusters oscillate in phase-shifted synchrony. The oscillatory behavior is governed by an electrolytic self-diffusiophoretic mechanism which involves alternating electric fields generated by the competing reduction and oxidation of silver. The oscillation frequency is tuned by changing the concentration of hydrogen peroxide. The addition of inert silica particles to the system results in hierarchical sorting and packing of clusters. Densely packed Ag PO particles form a non-oscillating core with an oscillating shell composed largely of silica microparticles.

Background:The physical basis for polymerase fidelity remains unclear. Results: Molecular dynamics simulations, NMR, and pre-steady-state kinetics of a mutator polymerase reveal conformational states of the active site that serve as fidelity checkpoints. Conclusion: Protein dynamics, largely concealed by x-ray crystallography, govern incorporation fidelity. Significance: Strategies have been inspired for engineering (anti)mutator polymerases and attenuated viruses.

We report an autonomous oscillatory micromotor system in which active colloidal particles form clusters, the size of which changes periodically. The system consists of an aqueous suspension of silver orthophosphate microparticles under UV illumination, in the presence of varying concentrations of hydrogen peroxide. The colloid particles first attract each other to form clusters. After a short delay, these clusters abruptly disperse and oscillation begins, alternating between clustering and dispersion of particles. After a cluster oscillation initiates, the oscillatory wave propagates to nearby clusters and eventually all the clusters oscillate in phase‐shifted synchrony. The oscillatory behavior is governed by an electrolytic self‐diffusiophoretic mechanism which involves alternating electric fields generated by the competing reduction and oxidation of silver. The oscillation frequency is tuned by changing the concentration of hydrogen peroxide. The addition of inert silica particles to the system results in hierarchical sorting and packing of clusters. Densely packed Ag3PO4 particles form a non‐oscillating core with an oscillating shell composed largely of silica microparticles.

We present a model to describe oscillations and collective behavior in a heterogeneous system of active colloidal clusters whose motility and interactions are driven by an oscillatory chemical reaction, as motivated by experimental observations of collective behavior in silver phosphate clusters under UV light in the presence of hydrogen peroxide, where spatiotemporal correlations in cluster behavior are presumably modulated by diffusive communication between clusters. A generic model for a single bistable cluster becomes oscillatory upon introduction of inter-cluster interactions that relate to localized emission or consumption of diffusing species. Multicluster simulations capture the qualitative features in the experimentally observed spatio-temporal correlations in the oscillations of nearby clusters. Since the model is generic and does not rely upon a particular chemical mechanism, it can be applied to other active matter systems exhibiting collective behavior, where interactions between bistable entities can drive collective oscillations.