Rational hapten design to produce high-quality antibodies against carbamate pesticides and development of immunochromatographic assays for simultaneous pesticide screening.

Carbamate pesticides (CPs) are the most used pesticides in agricultural production and pest control. In this study, carbofuran, isoprocarb and carbaryl were employed as models, and a general hapten strategy based on carbamate moiety recognition was proposed. Molecular modeling of the three-dimensional (3D) structure and surface electrostatic potential of the CPs indicated that the amide group formed by conjugation significantly influenced recognition by antibodies. The proposed strategy was used to obtain three sensitive and specific monoclonal antibodies (mAbs) with IC50 values of 1.4 ng/mL, 8.4 ng/mL and 13.8 ng/mL for carbofuran, isoprocarb and carbaryl, respectively. Negligible cross-reactivity (%) with analogs was observed, except for fenobucarb (84.6%) for isoprocarb. The obtained antibodies were used to develop an immunochromatographic assay (ICA) to simultaneously and quantitatively detect the three CPs. A strip reader was used to determine the limits of quantitation (LOQs) as 0.05 ng/mL (carbofuran), 31.3 ng/mL (isoprocarb) and 31.3 ng/mL (carbaryl). The recoveries of cucumber and Chinese cabbage samples ranged from 76% to 111%, with CVs from 1.3% to 10.6%, indicating good potential for the rapid simultaneous detection of multiple pesticide residues in a large batch of samples.