Self-assembly of upconversion nanoclusters with an amphiphilic copolymer for near-infrared- and temperature-triggered drug release

Multifunctional triggered drug release systems have been one of the most intriguing and challenging topics. In this study, we synthesize amphiphilic copolymers composed of hydrophilic oligo ethylene glycol methyl ether methacrylate and hydrophobic azobenzene-containing methacrylate. These amphiphilic copolymers can easily self-assemble into micelles in aqueous media and show smart responses to temperatures, UV/vis lights and ions. Interestingly, the obtained copolymers can self-assemble onto hydrophobic upconversion nanoparticles in aqueous media via hydrophobic interaction to form hybrid colloidal clusters with the hydrophobic nanocrystal core and hydrophilic polymeric shell. The hybrid colloidal clusters exhibit a thermo-responsive and photosensitive performance. When served as a drug carrier, both the near-infrared light and temperature triggered drug release can be realized, which have potential applications in intelligent drug delivery.