Hollow Polymeric Capsules from POSS-Based Block Copolymer for Photodynamic Therapy

Abstract

A novel amphiphilic diblock copolymer, PHEMAPOSS-b-P(DMAEMA-co-CMA), was prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization, where PHEMAPOSS block was first synthesized using a methacrylate monomer based on polyhedral oligomeric silsesquioxane (HEMAPOSS), and PHEMAPOSS was further utilized to prepare the block copolymer via RAFT copolymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and reduction-cleavable coumarin methacrylate (CMA) monomer. PHEMAPOSS-b-P(DMAEMA-co-CMA) could self-assemble in water to form spherical micelles with POSS core and stimuli-responsive shell. The micelles were cross-linked by photodimerization of coumarin, and then hollow polymeric capsules could be finally obtained via etching the POSS core in the solution of hydrofluoric acid (HF). The morphologies of the micelles and hollow polymeric capsules were well characterized by TEM, SEM, and DLS. The hollow polymeric capsules are responsive to typical physiological stimuli such as pH, and re...