What governs droplet size distributions in cells

Determine the physical mechanisms and governing parameters that set the size distribution of biomolecular condensate droplets in living cells, quantifying the relative contributions of coalescence, nucleation, and the material properties of the surrounding cellular environment under realistic intracellular conditions.

Background

In passive phase separation, competing processes such as Ostwald ripening and coalescence control how many droplets persist and how their sizes evolve over time. The review summarizes how kinetics (e.g., diffusion-limited versus conversion-limited growth), material properties (e.g., viscoelasticity, charges, elastic heterogeneities), and hydrodynamics modulate coarsening rates and size-selection.

Despite extensive theory for simple binary mixtures, intracellular condensates exist in complex environments where trapped species, sub-diffusion, elastic confinement, and active turnover can all modify coarsening. The paper highlights evidence suggesting a role for competition between coalescence and nucleation and for the mechanical properties of the surroundings, but emphasizes that the controlling factors in cells remain unresolved.