An ultrasensitive biosensor based on MXene/AuNPs modified electrode for organophosphorus pesticides detection via AChE inhibition strategy

Organophosphorus pesticides (OPs) pose significant risks to food safety and environmental health, making the development of sensitive and reliable detection methods highly desirable. In this work, a highly sensitive electrochemical biosensor based on a MXene/gold nanoparticles (AuNPs)/acetylcholinesterase (AChE) composite was constructed for the detection of OPs. Owing to the large specific surface area and excellent conductivity of MXene, together with the stable immobilization of AChE via Au S bonds, the proposed biosensor exhibits enhanced electron transfer efficiency and enzymatic activity retention. Under optimized conditions, the biosensor shows a wide linear response toward OPs, with a low detection limit of 0.008 ng·mL −1 , calculated based on the 3 σ / k criterion. The sensor also demonstrates good selectivity against common interfering species, satisfactory reproducibility, and excellent batch-to-batch repeatability. Furthermore, the applicability of the biosensor was validated by the determination of OP residues in various real samples, including apples, and cabbages, with recoveries ranging from 96.36% to 103.31% and relative standard deviations below 3.0%. Owing to its simple fabrication procedure and compatibility with portable electrochemical devices, the proposed sensing platform shows great potential for on-site and rapid monitoring of OPs in food and agricultural products.