CAT and cancer: MXenes exhibit enzyme-like activity by which they can act as peroxidase and oxidase enzymes to catalyse the oxidation of the substrate.93,94 Additionally, MXenes serve as a superoxide dismutase and catalase to scavenge excess ROS within cancer cells.95,96 When exposed to NIR-II (1064 nm) laser irradiation, this activity reduces hypoxic tumor microenvironment conditions similar to catalase activity, and diminishes glutathione levels as a glutathione-peroxidase analog.