Ligand-Defect Modulation of UiO-66(Ce) Unlocks Oxygen-Vacancy-Driven Glyphosate Hydrolysis and Sensitive Detection

A biomimetic dual-function nanozyme based on a cerium-based metal–organic framework (UiO-66(Ce)-3) with engineered oxygen vacancies was developed for efficient hydrolysis and sensitive detection of glyphosate. Acetic acid-triggered “missing-linker” defects partially disrupted the Ce–O coordination environment, generating oxygen vacancies and exposing Ce 3+ /Ce 4+ redox sites. The Ce 4+ centers polarize the phosphate bond, while the adjacent Ce 3+ sites facilitate the nucleophilic cleavage of the C–P bond. Under alkaline conditions, UiO-66(Ce)-3 showed excellent organophosphorus hydrolase-like activity with a k cat of 57.77 s –1, an SA of 0.70 U·mg –1, and a k cat / K m of 152.04 × 10 3 M –1 s –1 . The nanozyme effectively mitigated the glyphosate-induced toxicity in plants with a survival rate of 95%. Furthermore, the oxygen vacancies endowed pH-switch enzyme-like activity. With the pH at 4.0, UiO-66(Ce)-3 showed oxidase-like activity, which could realize high-sensitivity detection of glyphosate via point-of-care testing (LOD of 11.66 ng·mL –1 ) with good stability and reusability. And it showed a good recovery of 93.51%–110.19% in complex matrices, validation against the HPLC. The prepared pH-switchable nanozyme provides a novel approach to the detection and degradation of organophosphorus compounds.