Figure 1.

The multiple CNP enzymatic-like activities. Superoxide dismutase-like activity: CNPs reduce superoxide to hydrogen peroxide, oxidizing Ce³⁺ to Ce⁴. Catalase-like activity: CNPs oxidize hydrogen and molecular oxygen, reducing Ce⁴⁺ to Ce³⁺. The coupling of these two functions constitutes CNPs’ auto-regenerative redox cycle. Phosphatase-like activity: CNPs dephosphorylate para-nitrophenyl phosphate (p-NPP) in aqueous environments independently of the Ce^3+/4+ redox switch and possibly due to oxygen vacancies [113]. Haloperoxidase-like activity: CNPs mediate the oxidation of halides (B, Cl, and I) by H₂O₂ into hypohalous acid (HOX) species. Photolyase-like activity: CNPs enable selective cleavage of dimers (e.g., cyclobutane pyrimidine dimers (CPDs)) into monomers. Oxidase-like activity: CNPs oxidase the colorimetric substrate 3,3′,5,5′-tetramethylbenzidine (TMB) to its oxidized form ox-TMB.