Enzyme-mediated Ru@UiO-66@MnO2 NSs/thiamine-based ratiometric fluorescence sensor for visual detection of organophosphorus pesticide residues.

[Display omitted] • An enzyme-mediated ratiometric fluorescent probe was developed. • Ru@UiO-66 acted as a reference signal and thiamine acted as a response signal. • It integrated quenching effect, enzyme-like activity and enzyme inhibition. • It exhibited excellent analytical performance against dichlorvos and chlorpyrifos. • Ratiometric fluorescent hydrogels were developed for portable visual detection. In view of the potential hazards of organophosphorus pesticides (OPs), this paper constructed a ratiometric fluorescent probe utilizing a functionalized metal–organic framework to detect OPs. Ru(bpy) 3 Cl 2 was encapsulated inside UiO-66 as a reference signal, and MnO 2 nanosheets (MnO 2 NSs) were grown on the surface to obtain Ru@UiO-66@MnO 2 NSs. Acetylcholinesterase catalyzed the decomposition of acetylcholine into reductive thiocholine, which consumed MnO 2 NSs, thus restoring the Ru@UiO-66 fluorescence. Due to the enzymatic inhibition of OPs and the redox reaction between MnO 2 NSs and thiamine, this probe emitted blue fluorescence in the presence of OPs. The probe achieved linear responses to dichlorvos and chlorpyrifos with LODs of 9.99 × 10-6 μg mL−1 and 9.99 × 10-5 μg mL−1. The probe exhibited a satisfactory recovery rate for OPs in green tea. Furthermore, a hydrogel detection platform was developed by embedding the probe into sodium alginate. Overall, this work provides a visual approach to detect OPs in agricultural products. [ABSTRACT FROM AUTHOR]