Reactive polymeric micelles with disulfide groups in the coronae

Abstract

Micelles self-assembled by block copolymers are widely used in nanoscience and biomedical science. In the past few decades, much effort has been applied to the synthesis, characterization and applications of the polymeric micelles. However, previous research studies have paid less attention to the functionalization of coronae of the micelles. Herein, micelles with disulfide groups in the coronae were prepared and the micelles were used as a platform for functional modification reactions. Polystyrene-block-poly(oligo(ethylene glycol)monomethyl ether methacrylate)-block-poly(oligo(ethylene glycol)monomethyl ether methacrylate-co-2-((2-hydroxyethyl)disulfanyl)ethyl methacrylate), PS-b-PPEGMA-b-P(PEGMA-co-HDSMA), triblock copolymer was synthesized by RAFT polymerization. In aqueous solution, the triblock copolymer self-assembled into micelles with disulfides in the coronae. Upon cleavage of the disulfide bonds, thiol groups were produced in the coronae, and the micelles were able to undergo oxidation-induced aggregation. Hydroethyl disulfide groups in the PS-b-PPEGMA-b-P(PEGMA-co-HDSMA) triblock copolymer were converted to pyridyl disulfide groups by cleavage of the S–S bonds with tributylphosphine and reaction with dipyridyl disulfide. In PBS buffer solution, the modified triblock copolymer self-assembled into micelles with pyridyl disulfides in the coronae. The micelles were used as a platform for the preparation of glutathione or fluorescent group-decorated micelles. The antioxidant properties and the fluorescence properties of the functional micelles are reported in this paper. On the basis of this method, many different functional micelles can be prepared.