Coordinated pH/redox dual-sensitive and hepatoma-targeted multifunctional polymeric micelle system for stimuli-triggered doxorubicin release: Synthesis, characterization and in vitro evaluation

Abstract

Multifunctional polymeric micelles self-assembled from a DOX-conjugated methoxypolyethylene glycols-b-poly (6-O-methacryloyl-d-galactopyranose)-disulfide bond-DOX (mPEG-b-PMAGP-SS-DOX) copolymer were prepared as an antitumor carrier for doxorubicin delivery, of which the chemical modification with disulfide bonds and hydrazone bonds allowed micelles to release doxorubicin (DOX) selectively at acidic pH and high redox conditions. The resulting micelles exhibited coordinated pH/redox dual-sensitive and hepatoma-targeted multifunction with sustaining stability in aqueous media. The multifunctional micelles showed spherical shapes with a mean diameter of 93±2.08nm, a low polydispersity index (PDI) of 0.21, a low CMC value of 0.095mg/mL, a high drug grafting degree of 56.9% and a drug content of 39.0%. Remarkably, in vitro drug release studies clearly exhibited a pH and redox dual-sensitive drug release profile with significantly accelerated drug release treated with pH 5.0 and 10mM GSH (88.4% in 72h) without drug burst release. The tumor proliferation assays indicated that DOX-grafted micelles, along with low cytotoxicity and well biocompatibility to normal cells up to a concentration of 10μg/mL, inhibited the proliferation of HepG2 cells in a formulation-, time- and concentration-dependent manner in comparison with MCF-7 cells which was similar to free DOX. Anticancer activity releaved that the disulfide-modified micelles possessed much higher anti-hepatoma activity with a low IC50 value of 1.1μg/mL following a 72h incubation. Furthermore, the intracellular uptake tested by CLSM and FCM demonstrated that multifunctional polymeric micelles could be more efficiently taken up by HepG2 cells compared with MCF-7 cells, agreed well with MTT assays, suggesting these well-defined micelles provide a potential drug delivery system for dual-responsive controlled drug release and enhanced anti-hepatoma therapy.