Design of Mn-based nanozymes with multiple enzyme-like activities for identification/quantification of glyphosate and green transformation of organophosphorus

Abstract

A Mn-based nanozyme, Mn-uNF/Si, with excellent alkali phosphatase-like activity was designed by in-situ growth of ultrathin Mn-MOF on the surface of silicon spheres, and implemented as an effective solid Lewis-Brønsted acid catalyst for broad-spectrum dephosphorylation. H₂¹⁸O-mediated GC-MS studies confirmed the cleavage sites and the involvement of H₂O in the new bonds. DRIFT NH₃-IR and in-situ ATR-FTIR confirmed the coexistence of Lewis-Brønsted acid sites and the adjustment of adsorption configurations at the interfacial sites. In addition, a green transformation route of "turning waste into treasure" was proposed for the first time ("OPs→PO₄^3-→P food additive") using edible C. reinhardtii as a transfer station. By alkali etching of Mn-uNF/Si, a nanozyme Mn-uNF with laccase-like activity was obtained. Intriguingly, glyphosate exhibits a laccase-like fingerprint-like response (+,-) of Mn-uNF, and a non-enzyme amplified sensor was thus designed, which shows a good linear relationship with Glyp in a wide range of 0.49-750 μM, with a low LOD of 0.61 μM, as well as high selectivity and anti-interference ability under the co-application of phosphate fertilizers and multiple pesticides. This work provides a controllable methodology for the design of bifunctional nanozymes, which sheds light on the highly efficient green transformation of OPs, and paves the way for the selective recognition and quantification of glyphosate. Mechanistically, we also provided deeper insights into the structure-activity relationship at the atomic scale.

Keywords: Laccase mimic; Nanozymes; Organophosphorus pesticides; Phosphatase mimic; Solid acid catalyst.