A "three-in-one" detection platform based on cerium-coated metal-organic framework for multimodal glyphosate...

Glyphosate (Glyp) is a widely used herbicide, but its through prolonged and excessive spraying residues pose significant health risks. A ratiometric multimodal sensing platform combining fluorescence, colorimetry, and photothermal detection was developed for Glyp detection using a cerium/polyacrylic acid-modified porphyrin-based metal-organic framework (PCN@PAA-Ce). The detection strategy relies on the inhibition of acetylcholinesterase by Glyp, the oxidase-like activity of PCN@PAA-Ce, and the competition between enzymatic products and 3,3',5,5'-tetramethylbenzidine (TMB). Glyp inhibits acetylcholinesterase, which prevents the hydrolysis of acetylthiocholine and the production of reduced thiocholine. The oxidase-like property of PCN@PAA-Ce facilitates the oxidation of TMB (colorless) to oxidized TMB (oxTMB) (blue-green), while fluorescence resonance energy transfer caused oxTMB to quench the red fluorescence of PCN@PAA-Ce. Under ultraviolet light, the probe solution exhibits yellow-green fluorescence as a reference signal. Additionally, the excellent photothermal conversion of oxTMB enables the probe to respond to Glyp through photothermal responses. The detection ranges in the three modes were 1 × 10^-5 to 4 mg mL^-1, 1 × 10^-4 to 6 mg mL^-1, and 1 × 10^-4 to 6 mg mL^-1, respectively, with detection limits of 9.85 × 10^-6 mg mL^-1, 8.69 × 10^-5 mg mL^-1, and 9.72 × 10^-5 mg mL^-1, respectively. Compared to a single-mode probe, the multimodal probe's self-verification function provides more accurate and stable detection, offering broader potential for application.