Fe/Mo bimetallic oxide nanozyme achieves self-sufficient ROS cascade catalysis for cancer catalytic therapy.

Reactive oxygen species (ROS)-mediated catalytic therapy represents a promising candidate for tumor treatment, yet most current systems rely on external energy stimulation or exogenous substrates, limiting therapeutic efficiency in the heterogeneous tumor microenvironment (TME). Herein, we report a Fe/Mo bimetallic oxide nanozyme supported by carbon nanospheres (Fe₂(MoO₄)₃/C) that achieves self-sufficient ROS cascade catalysis for efficient cancer catalytic therapy. The nanozyme simultaneously exhibits superoxide dismutase (SOD)-like and peroxidase (POD)-like activities, enabling autonomous ROS amplification entirely driven by endogenous tumor microenvironment components. Specifically, endogenous superoxide anion (•O₂-) is catalytically converted into H₂O₂ via SOD-like activity, followed by POD-like conversion of H₂O₂ into highly cytotoxic hydroxyl radicals (•OH) under acidic TME conditions, thereby establishing a substrate self-sufficient ROS cascade without exogenous H₂O₂ supplementation or external stimulation. Fe₂(MoO₄)₃/C demonstrated markedly enhanced catalytic kinetics and ROS amplification compared with monometallic counterparts, resulting in pronounced oxidative stress, tumor cell apoptosis, and proliferation inhibition. In a 4T1 breast tumor model, the nanozyme achieved significant tumor growth suppression while exhibiting a favorable safety under the present experimental conditions. This work establishes a self-sufficient catalytic mechanism for continuous ROS amplification and provides a promising strategy for precise and efficient tumor catalytic therapy.