Reduction-active polymeric prodrug micelles based on α-cyclodextrin polyrotaxanes for triggered drug release and enhanced cancer therapy.

As one of the medical polymers approved by US Food and Drug Administration (FDA), poly(ethylene glycol) has low toxicity, high stability, good biocompatibility, unique physical and chemical properties. Cyclodextrin is an ideal candidate as a drug carrier due to its special structures and characteristics. These two materials were successfully assembled through chemosynthesis in combination with the hydrophilic poly(ethylene glycol) methyl ether methacrylate (OEGMA) chain and hydrophobic polymeric camptothecin (CPT) chain by atom transfer radical polymerization (ATRP). The introduction of disulfide bond of monomer was aimed to realize reduction agent-triggered release of active CPT. The obtained amphipathic prodrug [(Denoted as PC-PCPT-b-POEGMA (PCCO)] could form nano-sized polymeric micelles, which could release more than 85% of the loaded CPT via triggered cleavage of the disulfide linker. The cellular co-localization study revealed the potential pathway of drug internalization. Moreover, the PCCO micelles showed good biocompatibility in vivo after intravenous injection on a mouse model. This new CPT-loaded prodrug system could be prepared with low cost, and showed efficient and controlled drug release and favorable biocompatibility, demonstrating a promising potential as a stimuli-responsive polymeric prodrug for future clinical applications.