Electrochemical Sensing of Organophosphorus Pesticides Based on Plant Esterase-Triggered Silver Deposition with CuNi-DAC Signal Amplification

Residual organophosphorus pesticides (OPs) in food pose a severe threat to public health, necessitating simple and sensitive on-site analytical methods. In this study, a signal-off electrochemical sensing platform for OPs was constructed based on the OP-induced inhibition of silver deposition triggered by red kidney bean esterase (RKBE), coupled with the signal amplification of a CuNi dual-atom catalyst (CuNi-DAC). RKBE catalyzes the hydrolysis of α-naphthyl acetate to produce α-naphthol, which reduces Ag⁺ to Ag 0 deposited on the electrode. The electroactive Ag 0 undergoes oxidation to generate a prominent oxidation current, providing a sensitive sensing signal for detection. CuNi-DAC modification of the electrode accelerates charge transfer, provides more active sites, and effectively amplifies the sensing signal. Upon exposure to OPs, the activity of RKBE is inhibited, thereby suppressing the production of α-naphthol. This leads to a diminished Ag 0 generation and subsequent a weakened oxidation current. The decrease degree of current signal shows a positive correlation with pesticide concentration. Under optimized conditions, the fabricated sensing platform exhibits a good linear response range of 10 pmol/L-1000 pmol/L for fenthion with a low detection limit of 5.4 pmol/L. Spiked recoveries in cabbage and apple samples ranged from 93.3% to 108.5%, validating the sensing platform's practicality and reliability. This work offers a facile and cost-effective electrochemical sensing approach for on-site screening of OPs.