Hapten Design, Antibody Engineering, and Immunochromatographic Application: A Rapid Fluorescent Strip for Acephate Residue Detection

Abstract Acephate (AP) is one of the most extensively used organophosphorus insecticides worldwide. Its high water solubility and environmental mobility result in frequent residue detection in agricultural products, posing health risks to consumers. In this study, a specific monoclonal antibody (mAb) against AP was generated through computer technology-assisted hapten design. A recombinant monoclonal antibody (R-mAb) was further obtained by gene sequencing and recombinant expression, exhibiting a higher affinity constant (7.29 × 109 L/mol) than the parental mAb (5.60 × 109 L/mol). Using R-mAb as the recognition reagent, a fluorescent immunochromatographic assay (FICA) strip was established. Matrix matched calibration curves for lettuce, orange, Flammulina filiformis, and soybean yielded IC50 values of 2.5, 2.3, 2.0, and 24.0 μg/kg, respectively. Recoveries at 5 and 50 μg/kg were 84.9%–102.5%, agreeing well with liquid chromatography tandem mass spectrometry. The strip provides a convenient, efficient, and reliable tool for rapid screening of AP residues in agricultural products.