Reactive oxygen species-sensitive chondroitin sulfate A-cholesteryl hemisuccinate micelles for targeted doxorubicin delivery in tumor therapy

The efficient drug release triggered by the tumor microenvironment is challenging in the development of stimuli-sensitive nanomedicine. In this study, we developed novel polymeric micelles sensitive to reactive oxygen species (ROS) for targeted delivery of doxorubicin (DOX) in tumor therapy. Hydrophilic chondroitin sulfate A (CSA) was conjugated with cholesteryl hemisuccinate (CHS) via a ROS-cleavable thioketal (TK) bond. The resulting CSA-TK-CHS could form self-assembled micelles, and DOX-loaded CSA-TK-CHS (CSA-TK-CHS/DOX) micelles displayed a nearly spherical shape with an average hydrodynamic diameter of 324 nm. The bioresponsive DOX release of CSA-TK-CHS/DOX micelles was evaluated in an H 2 O 2 -containing phosphate buffer solution (PBS). CSA-TK-CHS/DOX micelles showed higher cellular uptake than free DOX in 4T1 cells by confocal laser scanning microscopy (CLSM) observation. And CSA-TK-CHS/DOX improved DOX cytotoxicity against CD44-overexpressed 4T1 and CT26 tumor cells. Notably, CSA-TK-CHS/DOX micelles displayed significantly stronger potency ( P  < 0.01) in antitumor activity than DOX·HCl in orthotropic 4T1-bearing Balb/c mice. Overall, these findings indicate that amphiphilic CSA-TK-CHS micelles are a promising targeted and intelligent drug carrier for tumor therapy.