Graphene quantum dots as metal-free nanozymes for chemodynamic therapy of cancer

Metal-based nanozymes have shown remarkable potential as therapeutic agents for cancer treatment. However, the issue of off-target side effects associated with metal toxicity remains a significant challenge. Here, we synthesized N/P co-doped graphene quantum dots (NPGQDs) as metal-free nanozymes for catalytic tumor therapy. NPGQDs were derived from erythrocyte membranes, ensuring the absence of organic precursors and solvents that could potentially contaminate the final product. NPGQDs efficiently converted hydrogen peroxide into hydroxyl radicals, leading to intracellular oxidative damage and inhibition of tumor cell proliferation. The exceptional peroxidase-mimetic enzymatic activity of NPGQDs was attributed to a synergistic electron effect resulting from co-doping N and P in GQDs. The in vivo experiments demonstrated that NPGQDs exhibited excellent biocompatibility and that the treatment with NPGQDs significantly suppressed tumor growth and prolonged survival without the need for therapeutic drugs. This drug-free, target-specific, and biologically benign nanozyme holds great potential as a potent biocatalyst for safe cancer treatment.