Dual-Mode Detection of Glyphosate Based on DNAzyme-Mediated Click Chemistry and DNAzyme-Regulated CeO2 Peroxidase-like Activity

In this article, a dual-signal sensor for the fluorescence and colorimetric detection of glyphosate (Gly) is developed based on DNAzyme-mediated click chemistry and DNAzyme-regulated CeO₂ peroxidase-like activity. DNAzyme can bind to Cu⁺, triggering a click chemistry reaction between 3-Azido-7-hydroxycoumarin (AHC) and 3-ethyn-1-ol (BOL), thus generating a strong fluorescence signal at 475 nm. Due to the strong coordination between Gly and Cu²⁺, the amount of reduced Cu⁺ decreases, resulting in a weakening of the fluorescence. In addition, Gly can inhibit the catalytic site of CeO₂ enzyme activity, while DNAzyme, which does not participate in the click chemistry reaction, can be adsorbed by CeO₂, further inhibiting the enzyme activity and reducing the oxidation color change of 3,3',5,5'-tetramethylbenzidine (TMB). The fluorescence detection limit of this dual-mode sensing platform is 0.15 μg/mL, and the colorimetric detection limit is 0.19 μg/mL. This method has been successfully applied to the detection of Gly in tap water and soybeans, which has a promising application in pesticide residue detection.