Pt@Fe-MIL-88 Enabled Natural-Enzyme-Free Dual-Mode Assay for Highly Selective Detection of Glyphosate.

Compared with natural-enzyme-based detection strategies, nanozymes offer notable advantages in stability, environmental tolerance, and cost-effectiveness. In this study, we designed and synthesized a Pt@Fe-MIL-88 composite with both oxidase (OXD)-like activity and intrinsic fluorescence. The material efficiently catalyzes 3,3',5,5'-tetramethylbenzidine (TMB) oxidation, generating a color change while quenching its fluorescence. Glyphosate (Gly) specifically inhibits the OXD-like activity of Pt@Fe-MIL-88, reducing oxTMB production and thereby alleviating fluorescence quenching, enabling dual colorimetric and fluorometric signal readout. The inhibition mechanism was elucidated through FTIR, XRD, XPS characterization, molecular dynamics simulations, and DFT calculations. Accordingly, a natural-enzyme-free, colorimetric-fluorometric dual-mode sensing platform for Gly was established. The platform exhibits high sensitivity, excellent selectivity, and strong anti-interference capability, with accuracy and reliability validated by spike recovery tests in real samples. This work presents a new strategy for developing stable, rapid, and low-cost multimodal detection methods for pesticide residues.