A highly salt-tolerant monoclonal antibody-based enzyme-linked immunosorbent assay for the rapid detection of phenylethanolamine A in urine

ABSTRACT Phenylethanolamine A (PEAA), as a typical β2-adrenoceptor agonist (β-AA), was widely illegally used in feed to improve the lean meat ratio. The detection performance of immunoassay, which is one of the effective methods to monitor PEAA residues in animal urine, has been hindered by high concentration of salt. Herein, we produced one highly salt-tolerant monoclonal antibody (mAb) 3E2 by hybridoma technology. Homologous modelling and molecular docking were used to analyse the antibody salt tolerance mechanism. Results show that the tight hydrophobic binding cavity is the key to high tolerance. Then the mAb 3E2 was used for specific detecting PEAA by enzyme-linked immunosorbent assay (ELISA) with the IC50 value of 0.36 ng mL−1and the LOD value of 0.065 µg L−1. Benefiting from the high salt tolerance of antibodies, swine urine and sheep urine spiked with PEAA can be detected directly by ELISA, and the acceptable recovery rates of 80.1–108.8% were obtained.