Hydrogen-bonded organic frameworks-loaded copper ions for fluorescence sensing: An enhanced sensitive enzyme inhibition assay for the organophosphates and carbamates detection

Organophosphorus (OPs) and carbamate (CMs) pesticides are widely used in agricultural production, which inevitably results in excessive pesticide residues in food. The traditional colorimetric enzyme inhibition method has low sensitivity and cannot achieve trace detection of pesticide residues in food. In this study, we combined the fluorescence of hydrogen-bonded organic frameworks (PFC-1-Cu 2 + ) with the inhibitory effect of pesticides on acetylcholinesterase. By inhibiting the acetylcholinesterase activity upon pesticides to decrease the choline production, a switch-off mode fluorescent emission can be achieved and then a fluorescent enzyme inhibition method for rapid and ultra-sensitive detection of multiple OPs and CMs in food was constructed. As a result, the limits of detection (LOD) for OPs and CMs were 0.19 ng/mL and 0.39 ng/mL, respectively, representing improvements of 33-fold and 27-fold compared to the colorimetric method. Additionally, three representative OPs or CMs (dichlorvos, profenofos and aldicarb sulfoxide) residues were detected in lettuce and rice by this method. The recoveries of the three pesticide residues in lettuce and rice by this method ranged from 81.63 % to 106.67 %, providing a new option for the sensitive detection of OPs and CMs.