O2‑Cu/ZIF-8@Ce6/ZIF-8@F127 Composite as a Tumor Microenvironment-Responsive Nanoplatform with Enhanced Photo-/Chemodynamic Antitumor Efficacy

Hypoxia and overexpression of glutathione (GSH) are typical characteristics of the tumor microenvironment, which severely hinders cancer treatments. Here, we design a novel biodegradable therapeutic system, O2–Cu/ZIF-8@Ce6/ZIF-8@F127 (OCZCF), to simultaneously achieve GSH depletion and O2-enhanced combination therapy. Notably, the doped Cu2+ doubles the O2 storage capacity of the ZIF-8 matrix, which makes OCZCF an excellent pH-sensitive O2 reservoir for conquering tumor hypoxia, enhancing the photodynamic therapy (PDT) efficiency of chlorin e6 (Ce6) under 650 nm laser irradiation. Moreover, the released Cu2+ can act as a smart reactive oxygen species protector by consuming intracellular GSH. The byproduct Cu+ will undergo highly efficient Fenton-like reaction to achieve chemodynamic therapy (CDT) in the presence of abundant H2O2. The accompanying O2 will further alleviate hypoxia. The in vitro and in vivo experimental data indicate that OCZCF could cause remarkable tumor inhibition through enhanced synergetic PDT and CDT, which may open up a new path for cancer therapy.