Smart Microcapsules Designed for On-Demand Local Heating and Drug Release

Chemophotothermal therapy is promising for cancer treatment with its synergistic effect. Although various photothermal agents have been formulated as drug carriers, low payload, burst release, and severe dilution usually restrict their uses. To overcome the limitations, we design smart microcapsules as a pragmatic material for chemophotothermal therapy. With a microfluidic device, water-in-oil-in-water (W/O/W) double-emulsion templates are produced to have photothermal polydopamine nanoparticles and drugs in the water core and a mixture of photocurable monomers and phase-change material (PCM) in the oil shell. The droplets are significantly shrunken by the osmotic extraction of water from the core, which enables the size reduction for the ease of injection and enrichment of polydopamine nanoparticles and drugs for enhanced photothermal performance and high payload. The microcapsules, produced by photopolymerization of monomers, release drugs when PCM in continuous nanochannels of the polymer shell is molten while retaining drugs without leakage when frozen. As the concentrated polydopamine nanoparticles provide rapid and drastic heating by near-infrared irradiation, the drug release can be switched on and off in a programmed manner by manipulating the irradiation. The smart microcapsules secure high drug payload in a spacious core, negligible initial bursting, and dilution-free high photothermal performance, potentially serving as a pragmatic therapy platform.