An in situ one-step route for the synthesis of Fe3O4@ZIF-8 core-shells with a high-peroxidase-like performance for the colorimetric detection of methyl parathion

Methyl parathion (MP) is a broad-spectrum agricultural insecticide. Human exposure to MP can affect the nervous, cardiovascular, and hepatic systems. In this research, a core–shell Fe3O4@zeolitic imidazolate framework-8 (ZIF-8) is developed as a peroxidase mimic for the rapid and simple colorimetric detection of MP. Fe3O4 nanoparticles were wrapped with ZIF-8 by a hydrothermal method to obtain core–shell structural Fe3O4@ZIF-8 nanocomposites. The synthesized Fe3O4@ZIF-8 possessed mimetic properties and effectively catalyzed the conversion of transparent solution to blue upon the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) by H2O2. Further, based on a classical reaction through acetylthiocholine chloride (ATCl) and cholesterol oxidase (ChOx), acetylcholinesterase (AChE) can generate H2O2, and that MP can exert an inhibitory effect on AChE. Within the range of 10 to 200 µg/L, the MP concentration demonstrated a remarkable linear response with the absorbance under optimum conditions, with a detection limit of 6.3 μg/L. Finally, the proposed approach enabled the detection of MP in cabbage. As an artificial peroxidase, Fe3O4@ZIF-8 demonstrated greater affinity for the substrate than horseradish peroxidase, which has a great application prospects in food safety and environmental safety.