(169bj) Size Is an Important Factor in Partitioning of Cargo Molecules into Liquid Condensates and Interfaces

Within biology, compartmentalization can be achieved through lipid membranes serving as barriers, or through the process of liquid phase separation of biomolecules. Compartments arising through the process of phase separation are generally termed biomolecular condensates (BMCs) and are formed by the attractive interactions between various biomolecules, particularly proteins and nucleic acids. Recent work has demonstrated that BMCs are permeable to many biomolecules, and that various factors may promote or oppose incorporation into a condensed proteinaceous droplet. We find that larger cargo molecules are more excluded from BMCs, and that even weak adhesive forces can drive them to associate with the surface. Using simulations and theory, we explore the interplay between attractive forces and surface enrichment inside condensates toward a general framework of predicting cargo partitioning into BMC interiors and interfaces, in agreement with experimental measurements.