Tumor-Microenvironment-Responsive Cerium-Enriched Copper Nanozyme with O 2 Supply and Oxidative Stress Amplification for In Situ Disulfiram Chemotherapy and Chemodynamic Therapy Intensification.

Traditional chemotherapy has faced tough challenges of systemic toxicity, hypoxia resistance, and inadequacy of monotherapy. Developing the tumor-specific O 2 -supply-enhanced chemotherapy without toxic drugs while combing other precise treatments can substantially improve therapeutic efficacy. Herein, a CeO 2 -enriched CuO nanozyme with O 2 supply and oxidative stress amplification for tumor-specific disulfiram (DSF) chemotherapy and intensified chemodynamic therapy by synergistic in situ "nontoxicity-toxicity" activation is developed. Notably, CeO 2 can not only act as a morphological "regulator," but also serve as a cascaded enzyme-mimetic catalyst via tumor-microenvironment-responsive cascaded-logical programmable valence conversion. Once internalized inside tumor cells, the nanozyme can be degraded by lysosomal acidity to release nontoxic DSF and Cu 2+ , which can trigger in situ "Cu 2+ -DSF" chelation, generating a highly toxic Cu(DTC) 2 for in situ chemotherapy. Moreover, the enriched CeO 2 with catalase-mimetic activity can decompose the endogenous H 2 O 2 into O 2 , which can relieve the hypoxia to enhance the chemotherapeutic efficacy. Furthermore, the simultaneously generated Ce 3+ can exert peroxidase-mimetic activity to catalyze H 2 O 2 into hydroxyl radicals (•OH) for chemodynamic therapy. This Fenton-like chemistry is accompanied by the regeneration of Ce 4+ , which can deplete the intracellular overproduced GSH to amplify the oxidative stress. Therefore, this nanozyme can provide an alternative to precise cancer treatment.