Glutathione-dependent micelles based on carboxymethyl chitosan for delivery of doxorubicin

Novel glutathione (GSH)-dependent micelles based on carboxymethyl chitosan (CMCS) were developed for triggered intracellular release of doxorubicin (DOX). DOX-33'-Dithiobis (N-hydroxysuccinimidyl propionate)-CMCS (DOX-DSP-CMCS) prodrugs were synthesized. DOX was attached to the amino group on CMCS via disulfide bonds and drug-loaded micelles were formed by self-assembly. The micelles formed core-shell structure with CMCS and DOX as the shell and core, respectively, in aqueous media. The structure of the prodrugs was confirmed by IR and proton nuclear magnetic resonance (¹H NMR) spectroscopy. The drug-loading capacity determined by UV spectrophotometry was 4.96% and the critical micelle concentration of polymer prodrugs determined by pyrene fluorescence was 0.089 mg/mL. Micelles were spherical and the mean size of the nanoparticles was 174 nm, with a narrow polydispersity index of 0.106. Moreover, in vitro drug release experiments showed that the micelles were highly GSH-sensitive owing to the reductively degradable disulfide bonds. Cell counting kit (CCK-8) assays revealed that DOX-DSP-CMCS micelles exhibited effective cytotoxicity against HeLa cells. Moreover, confocal laser scanning microscopy (CLSM) demonstrated that DOX-DSP-CMCS micelles could efficiently deliver and release DOX in the cancer cells. In conclusion, the DOX-DSP-CMCS nanosystem is a promising drug delivery vehicle for cancer therapy.