Temporal stimulus patterns drive differentiation of a synthetic coacervate

The fate of living cells often depends on their processing of temporally modulated information, such as the frequency and duration of various signals. Synthetic stimulus-responsive systems have been intensely studied for >50 y, but it is still challenging for chemists to create artificial systems that can decode dynamically oscillating stimuli and respond in the systems’ properties/functions, because of the lack of sophisticated reaction networks that are comparable with biological signal transduction. Here we report morphological differentiation of synthetic dipeptide-based coacervates in response to light pulse frequency. We designed a simple cationic diphenylalanine peptide derivative to enable formation of coacervates. The coacervates concentrated an anionic methacrylate monomer and a photo-initiator, which provided a unique reaction environment and facilitated light-triggered radical polymerisation—even in air. Pulsed light irradiation at 9.0 Hz (but not at 0.5 Hz) afforded anionic polymers. This frequency dependence is attributable to the competition of reactive radical intermediates between the methacrylate monomer and molecular oxygen. The frequency-dependent polymer formation enabled the coacervates to differentiate in terms of morphology and internal viscosity, with an ultrasensitive switch-like mode. Our achievements will facilitate rational design of smart supramolecular soft materials and are insightful regarding the origin of life.