Interfacial Polymerization Fabricated Polydopamine Capsules as a Step Toward a Photothermal Protocell Model

Abstract Photothermal is a significant solar energy conversion process on Earth, and photothermal‐responsive protocells are a potential model for prebiotic chemistry. Here, polydopamine microcapsules are fabricated via emulsion droplets‐templated interfacial polymerization and investigated their potential as synthetic protocell models for photothermal conversion and utilization. DNAzyme‐mediated dopamine peroxidation and polymerization occur at the water/oil interface of the emulsion droplets, facilitated by a biphasic microfluidic technique, leading to the formation of uniform polydopamine microcapsules, which retain structural integrity upon transfer into a continuous water phase. These microcapsules exhibit size‐dependent semi‐permeability and high photothermal capability due to their broad spectral absorbance. The photothermal‐mediated temperature rise within the microcapsules triggers DNA denaturation and rearrangement, and intermittent photothermal irradiation modulates reversible phase separation of DNA condensates, mimicking membrane‐less organelles. This work suggests that interfacial polymerization fabricated polydopamine capsules are a plausible photothermal protocell model that can demonstrate aspects of primitive abiotic cellularity.