Cancer-Selective Bioreductive Chemotherapy Mediated by Dual Hypoxia-Responsive Nanomedicine upon Photodynamic Therapy-Induced Hypoxia Aggravation.

Stimuli-responsive drug delivery has rendered promising utilities in cancer treatment. Nevertheless, cancer selectivity as well as sensitivity still remains critical challenges that would undermine the therapeutic efficacy of chemodrugs and cause undesired systemic toxicity. Herein, a dual hypoxia-responsive drug delivery system was developed to enable photodynamic therapy (PDT)-induced drug release and drug activation intermediated via PDT-induced hypoxia. Particularly, tumor-targeting and hypoxia-dissociable nanoparticles (NPs) were self-assembled from the amphiphilic polyethylenimine-alkyl nitroimidazole [PEI-ANI, (PA)] and hyaluronic acid-chlorin e6 (HA-Ce6) to encapsulate bioreductive chemodrug, tirapazamine (TPZ). After systemic administration, the obtained PA/HA-Ce6@TPZ NPs enabled effective tumor accumulation due to HA-mediated cancer targeting. Upon receptor-mediated endocytosis, light irradiation (660 nm, 10 mW/cm