Smart iron-based metal–organic framework nanovehicles gated with CuII-tannic acid coordination polymers for combination therapy of chemotherapy and chemodynamic therapy

Smart iron-based metal–organic framework MIL-101(FeIII) nanovehicles gated with CuII-tannic acid (TA) coordination polymers were constructed via "on site" self-assembly. The controlled release of antitumor drugs encapsulated within MIL-101(FeIII) mesopores was realized in response to the tumor microenvironments [such as low pH, glutathione (GSH), H2O2, and adenosine-5'-triphosphate (ATP)] and near infrared light, due to the photothermal effect of the nanocarriers, by the disassembly of the CuII-TA gating films and/or the degradation of the MIL-101(FeIII) nanocarriers. The low pH gave rise to the disassembly of the CuII-TA gating films and the release of drugs. The competitive coordination of ATP with CuII/FeIII caused the disassembly of the CuII-TA gating films, the degradation of the nanocarriers, and the release of drugs. The overexpressed GSH could reduce CuII/FeIII to CuI/FeII and resulted in the disassembly of the CuII-TA gating films and the degradation of the nanocarriers, and the produced CuI/FeII could catalyze H2O2 of elevated level to generate more hydroxyl radicals via the Fenton/Fenton-like reactions for cell apoptosis. The cascade reactions of the depletion of GSH and the generation of hydroxyl radicals based on the gated nanovehicles achieved chemodynamic therapy (CDT) besides chemotherapy. The smart nanovehicles have promising applications in combination tumor therapy of chemotherapy and CDT.