Pushing Structural Complexity in Protocells Toward Emergent Functionality

Protocells provide a promising platform for constructing life-like systems from the bottom up and understanding the physicochemical principles underlying cellular organization. Early protocell models primarily focused on minimal compartmentalization and simple biochemical functions, however, increasing evidence suggests that the emergence of complex cellular behaviours requires higher-order structural organization across multiple length scales. Recent advances in synthetic cells, soft matter, and systems chemistry have therefore shifted the field toward engineering structurally complex protocells with enhanced functional and collective capabilities. In this Review, we summarize recent progress in the construction of protocells with increasing structural complexity, including membrane-bounded condensate systems, multicompartmentalized architectures, and hierarchically organized assemblies. We further discuss how these structural features enable emergent functionalities such as spatially programmed reactions, signal transduction, adaptive communication, and collective organization. Particular emphasis is placed on the role of physicochemical interactions and matrix-mediated assembly in directing protocell organization into higher-order communities and tissue-like materials. Finally, we highlight current challenges and future opportunities in developing dynamically adaptive, non-equilibrium protocell systems that bridge the gap between simplified biomimetic compartments and autonomous synthetic living matter. This Review underscores structural complexity as a central design principle for driving protocells toward emergent functionality and life-like behaviours.