A Bioorthogonal Reaction Network Programs Selective Death in an Ensemble of Assorted Protocells

Liquid-liquid phase separated coacervates offer a reliable protocell platform for understanding fundamentals of cellular processes, disease progression, and bottom-up synthesis of minimal cells. Synthetic protocells replicate key non-equilibrium features of living systems through fuel-dependent compartmentalization, growth, adaptation, and destruction. However, a significant challenge remains in achieving programmed and irreversible control over their fates in a complex ensemble of protocells, akin to programmed cell death in natural cells known as apoptosis. Here, we introduce a fuel-driven coacervate that undergoes selective apoptosis by an orthogonal chemical signal. The signal receiving protocells are transiently created by activating a bivalent aldehyde-containing terephthalaldehyde monomer using bisulfite to generate a negatively charged α-hydroxy sulfonate, which undergoes phase separation with poly(hexamethylene biguanide) polymer through salt-bridge interactions. The resulting liquid-core membraneless protocell exhibits tunable lifetime, regulated by formaldehyde that regenerates the neutral aldehyde and concomitantly disassembles. When organized into communicating protocell populations, enzymatic formaldehyde production in one compartment selectively induces the programmed dissolution of target protocells, exhibiting autocrine and paracrine signaling behavior. Remarkably, the orthogonal formaldehyde signaling network enables fractional killing of target protocells in an ensemble of heterogenous protocell community, while preserving the phenotypes and native functional activities of non-targeted population. Together, this work establishes the utility of aldehyde-bisulfite chemistry in adaptable coacervates through charge reversal and competitive binding, showcasing a general strategy for constructing programmable, nonequilibrium cell-like systems. Beyond advancing the design of synthetic life-like materials, the approach holds great potential in designing bioorthogonal strategies for drug delivery, sensing, and therapeutics.