Specific-oxygen-supply functionalized core-shell nanoparticles for smart mutual-promotion between photodynamic therapy and gambogic acid-induced chemotherapy

Photodynamic therapy (PDT) and chemotherapy of cancer both meet respective challenges. Tumor hypoxia, low penetration and high glutathione (GSH) level bear the brunt. Herein, a core-shell nanoparticle, with multi-function of hypoxia-responsiveness, specific oxygen supply and deep tumor penetration, was constructed for smart mutual-promotion between the both to overcome the respective restrictions. The nano platform (GC@MCS NPs) was composed of hypoxia-responsive hyaluronic acid-nitroimidazole (HA-NI) as shells, MnO2 NPs as oxygen modulators and reduction-responsive functionalized poly (L-glutamic acid) derivatives (gamma-PFGA) as cores to deliver gambogic acid (GA) and Chlorine6 (Ce6). After endocytosis, the approximately 100 nm of GC@MCS NPs achieved hypoxia-responsive shell degradation and MnO2 release, followed by reduction-activated charge conversion to form positively charged cores. With the damage effect of superficial tumor cells by the partially released GA, GA&Ce6-loaded gamma-PFGA penetrated deep inside through electronic interaction step by step. Upon irradiated with 638 nm of laser, widely permeated Ce6 was activated for enhanced PDT under the high oxygenation by MnO2 NPs. The generated reactive oxygen species (ROS) in return facilitated the GA-induced paraptosis by clearing high level of GSH. As a result, this mutual promotion strategy contributed to 92.41% of 4T1 tumor inhibition rate, exhibiting outstanding advantages. Our GC@MCS NPs provided a smart combination of chemo-photodynamic therapy and focused on addressing the tumor hypoxia and low penetration issues.