Programming reconfigurable colloidal self-assembly with DNA circuits

Most complex cellular functions emerge from a hierarchical self-organization of biomolecules that is encoded in the genome, fueled by ATP, and modulated by multiple chemical cues. Applying the same paradigm to inert matter enables the design of functional materials that are programmable, active, and adaptable to their environment. To this end, we use the PEN enzymatic toolbox to program the assembly of micron-sized emulsion droplets decorated with mobile DNA linkers into colloidal clusters. We quantitatively track the formation, growth, and dissolution of adhesive DNA patches between droplets and link these dynamics to the underlying enzymatic activity. By tuning the volume ratio and sequence of interactions between different droplet species, we control the transient assembly of self-limited clusters with various shapes (ribbons, flowers, and checkerboards). Due to diffusive and reversible binding at the droplet's liquid interface, the clusters are densely packed yet reconfigurable, in contrast to fractal aggregates typically formed with solid colloids. Notably, upon the sequential activation of DNA linkers of varying strengths, we observe spontaneous cluster rearrangement and droplet segregation in core-shell patterns, resembling the behavior of living cells undergoing differential adhesion in biological tissues. Beyond biomimicry, this system opens new avenues for designing active colloidal materials, with potential applications in soft robotics or adaptable optical metamaterials.