Theory and simulation of reaction diffusion models of self-limiting droplet formation

Liquid droplets are a generic feature of biological systems. Within the cell, liquidlike substructures form that contain Cajal bodies, germ granules, and centrosomes. In the absence of surfactants or long ranged interactions, the thermodynamically stable phase separated state of a liquid will always be that which minimizes the surface area of the droplet resulting in macroscopic domains. For this reason, It remains unclear how cells mitigate the formation of such large scale structure. We discuss ways in which macroscopic domains can be avoided by slow coarsening dynamics accompanying gelation or active processes that modulate Ostwald ripening. Theory and computer simulations are used to understand the mechanisms of droplet formation and dynamics. Implications for T-cell signaling pathways are also discussed.