Diffusive and enzymatic modulation of the dynamic size distribution of DNA droplets

We investigate how material diffusion processes affects the temporal evolution of the radii of DNA droplets, using DNA nanoparticles whose phase-separation ability can be enzymatically degraded. The droplets are immobilized so as to disallow Brownian coalescence, and the their radius trajectories are captured using confocal fluorescent microscopy. Without enzymes, we observe very slow Ostwald ripening in rough agreement with the Lifshitz–Slyozov–Wagner theory. With enzymes, we observe a dynamic transition in the droplet shrinkage rate from R^{-3} to R^{-1}, suggesting a crossover from slow cooperative evaporation to fast independent droplet shrinkage. Interestingly, in the former regime, a dynamic radius distribution decouple in time and radius, leading to an unusual behavior in which the average radius remains constant despite the total droplet volume decreasing. Our work provides insights into the statistical dynamics of phase-separated droplets, with relevance to both biological condensates and materials applications.