Carboxymethyl dextran-based hypoxia-responsive nanoparticles for doxorubicin delivery

In an attempt to develop the hypoxia-responsive nanoparticles for cancer therapy, a polymer conjugate, consisting of carboxymethyl dextran (CMD) and black hole quencher 3 (BHQ3), was prepared. The polymer conjugate can self-assemble into nanoparticles (CMD-BHQ3 NPs) under aqueous conditions. The anticancer drug, doxorubicin (DOX), was loaded in CMD-BHQ3 NPs to prepare DOX@CMD-BHQ3 NPs. The CMD-BHQ3 NPs released DOX in a sustained manner under physiological conditions, whereas the release rate of DOX remarkably increased under hypoxic conditions throughout the cleavage of the azo bond in BHQ3. In vitro cytotoxicity study revealed that DOX@CMD-BHQ3 NPs showed higher toxicity under hypoxic conditions than normoxic conditions. Confocal microscopic images indicated oxygen-dependent intracellular release of DOX from DOX@CMD-BHQ3. In vivo biodistribution study demonstrated that CMD-BHQ3 NPs were preferentially accumulated in the tumor after systemic administration into tumor-bearing mice. Overall, CMD-BHQ3 might be a promising carrier for selective drug release in the hypoxic tumor.