Engineering sequential liquid–liquid phase separation and affinity partitioning for compartmentalization and functionalization of all-aqueous emulsion drops

Liquid-liquid phase separation (LLPS) is a physicochemical phenomenon in which two or more immiscible liquids separate under specific conditions, forming dispersed liquid compartments within a continuous medium. LLPS occurs in a wide range of systems, from intracellular biological processes to synthetic polymer solutions, and serves as an important guiding principle for the development of advanced biomaterials with precisely organized core–shell architectures and tailored functionalities. However, current LLPS-based strategies for achieving compartmentalization and functionalization of core–shell microstructures face significant challenges, as they typically require either exogenous agents or stepwise processing to achieve phase separation, while offering inadequate control over the spatial distribution and partitioning efficiency of functional components across compartments for concurrent and tailored functionalization. Herein, an integrated strategy is developed for realizing spatiotemporal compartmentalization and functionalization of all-aqueous emulsion drops by engineering sequential LLPS and affinity partitioning. Our approach leverages intrinsic concentration gradients within the all-aqueous emulsion drops to generate osmotic pressure gradients, enabling spontaneous sequential LLPS-based compartmentalization without requiring exogenous agents or multi-step fabrication, yielding stable core–shell microstructures with spatial and temporal control. Moreover, inspired by intracellular biomolecular partitioning mechanisms, we further achieve simultaneous functionalization of discrete core and shell regions by regulating the affinity partitioning-driven distribution of functional components across compartments, enabling efficient generation of core–shell microcapsules of performing sophisticated functions with spatiotemporal precision, as validated by their enhanced therapeutic performance in an infected wound healing model. This work establishes a versatile strategy for developing advanced biomaterials with sophisticated architectures that have potential for therapeutic applications.