A highly sensitive and specific immunochromatographic test strip for detecting p,p'-DDA in seawater and shellfish

P,p'-DDA, similar to DDT, accumulates in the food chain and poses potential risks to human health. Herein, a novel sensitive and specific mAb-10B4D7 was screened and subsequently rAb-10B4D7 was expressed by genetic engineering. Utilizing rAb-10B4D7, an immunochromatographic test strip (ITS) was developed with visual limit of detection 12.5 μg/L within 15 min, displaying no cross-reactivity with o,p'-DDT, p,p'-DDT, p,p'-DDD, and p,p'-DDE. Further, a linear relationship between log(concentration of p,p'-DDA) and the optical density ratio of test (T) line and control (C) line was established with limits of detection of 1.03 μg/kg, recoveries of 79.3-106.8 %, and coefficients of variation below 10 %. Molecular docking simulations identified two critical residues (Arg-H62, Phe-L98) forming three hydrogen bonds with p,p'-DDA, resulting in the high specificity and affinity of rAb-10B4D7, with a K_D of 5.81 × 10^-9 mol/L. These results indicated that the ITS was suitable for monitoring p,p'-DDA and organochlorine residues in seawater and shellfish.