Light-responsive and Biodegradable Block Polymer Synthesized by RAFT Polymerization and Its Potential Drug Carrier Properties

A well-defined, light-responsive copolymer poly(spiropyrane)-block-poly(ethylene glycol) (PSP-b-PEG) was synthesized by RAFT polymerization. The final copolymer can self-assembled into spherical micelles with a hydrophilic PEG corona and a hydrophobic spiropyrane core in aqueous solution. Moreover, the properties of micelles in aqueous solution were detected by fluorescence spectroscopy, UV–vis spectroscopy, dynamic light scattering (DLS), and scanning electron microscope (SEM). Model drug Nile Red was then encapsulated into the micelles and its light-controlled release was studied. In addition, an MTT assay provided the evidence for the low cell cytotoxicity of PSP-b-PEG micelles. The results demonstrate that the spherical micelles of PSP-b-PEG possess a potential application in smart drug delivery.Block polymer PEG-b-PSP could be self-assembled into micelles with a light-responsive hydrophobic block and stabilized by hydrophilic PEG coronae in aqueous solution, and the encapsulated drug can be released under UV light due to the transformation of SP structure to MC form.