Polymeric micelles prepared from post-polymerization modification of pentafluorophenyl ester-containing polymer

Abstract

Polymeric micelles assembled from amphiphilic copolymer have been recognized as effective vehicle for controlled delivery of therapeutic agents such as drug, gene, and protein. We have recently demonstrated that stepwise post-polymerization modification of a single pentafluorophenyl ester-bearing homopolymer can be used as a facile route to redox-responsive nanogels. Here in this research, we would like to explore further the versatility of this similar approach to fabricate pH responsive micelles. Poly(pentafluorophenyl acrylate) (PPFPA) was first synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Post-functionalization of PPFPA with varied equivalent of 1-amino-2-propanol yielded amphiphilic random copolymers of PPFPA-r-PHPA having different compositions. The copolymers can self-assemble to form micelles in aqueous with sizes of less than 200 nm. By reacting the pentafluorophenyl (PFP) groups remaining in the nanoparticles with 1-(3-aminopropyl) imidazole (API), pH responsive micelles were generated as evidenced by the disintegration of the nanoparticles upon decreasing pH from 7.4 to 5.0. This may be explained as a result of charge transition of the imidazole rings from neutral to positively charged upon pH reduction. These developed nanoparticles possess a strong potential to be used as carriers for targeted delivery of therapeutic agent of which the release can be triggered under an acidic condition.