Reactive oxygen species (ROS) generators are sparking breakthroughs in sensitization and treatment of therapy-resistant tumors, yet the efficacy is drastically compromised by limited substrate concentrations, short lifetimes of free radicals, and restricted oxidative damage. Herein, a flower-like nanozyme with highly permeable leaflets accommodating catalytic metal sites was developed to address the challenges by boosting substrate and product accessibility. In the formation of a zeolite imidazole framework, cobalt ions promoted catalytic polymerization and deposition of polydopamine. The polymers acted as a stiffener for preventing framework collapse and maneuvering pore reopening during carbonization. The cobalt single-atom/cluster sites in the highly porous matrix generated peroxidase/oxidase-like activities with high catalytic efficiency (Kcat/Km) up to 6 orders of magnitude greater than that of conventional nano-/biozymes. Thereby, a robust ROS storm induced by selective catalysis led to rapid accumulation of oxidative damage and failure of antioxidant and antiapoptotic defense synchronization in drug-resistant cancer cells. By synergy of a redox homeostasis disrupter co-delivered, a significantly high antitumor efficiency was realized in vivo. This work offers a route to kinetically favorable ROS generators for advancing the treatment of therapy-resistant tumors.
Keywords: ROS storm; catalysis kinetics; permeable structure; porous nanozyme; tumor therapy.