Development of a highly sensitive immunochromatographic strip based on an anti-chlorpropham antibody: Optimizing haptens for enhanced performance

The use of chlorpropham (CIPC) in crops may lead to residual contamination in food products, raising food safety concerns. In this study, we developed a colloidal gold immunochromatographic assay (CG-ICA) based on a highly sensitive monoclonal antibody (mAb) for rapid and convenient monitoring of CIPC residues in food and water samples. Computer-aided analysis integrated with antiserum assays systematically elucidated the structure-activity relationship between the structural features of CIPC haptens and antibody performance. The findings demonstrate that retention of the target molecule's key functional groups in hapten design is critical for both target-specific recognition and improved antibody sensitivity. These results provide critical molecular design guidelines for developing high-efficiency haptens and generating high-performance mAbs. Subsequently, we obtained an mAb exhibiting a limit of detection of 0.046 ng/mL and a half-maximal inhibitory concentration of 0.56 ng/mL in an indirect competitive enzyme-linked immunosorbent assay. The CG-ICA effectively detected CIPC in water (0.18–20 μg/L) and food matrices (potatoes and carrots; 1.93–500 μg/kg), with recovery rates of 90.60 %–111.36 % and coefficients of variation ranging from 2.50 % to 8.60 %, confirming its reliability for practical sample analysis. This study represents an innovative approach to CIPC detection in food and environmental samples. The developed assay offers rapid analysis, simple operation, and straightforward result interpretation, making it an ideal tool for on-site CIPC residue monitoring that can significantly enhance regulatory efficiency and food safety assurance.