Highly Specific Anti-tylosin Monoclonal Antibody and Its Application in the Quantum Dot Bead-Based Immunochromatographic Assay

In this study, mAb-5A7 and mAb-1D7, two highly specific monoclonal antibodies against tylosin (TYL), were prepared by using hapten TYL-carboxymethoxylamine hemihydrochloride (TYL-CMO), and they showed IC50 values of 13.84 ng/mL and 13.01 ng/mL and LODs of 1.21 and 0.98 ng/mL, respectively, in indirect competitive enzyme-linked immunosorbent assay. An immunochromatographic assay based on quantum dot (QD)-embedded nanobead (QB-ICA) and mAb-1D7 was developed for the detection of TYL in milk and honey. The IC50 values of QB-ICA in PBS, milk, and honey were calculated to be 22.4, 18.5, and 24.41 ng/mL, with LODs of 2.32, 1.84, and 2.69 ng/mL, respectively, satisfying the requirement of the maximum residue limit for TYL in food samples of 100–300 μg/kg in China. The cross-reactivity (CR) values with two related compounds, tilmicosin and abamectin, were 4.48% and 1.87%, respectively, and the CR values with other drugs were all less than 0.2%, which indicated that the developed QB-ICA was highly specific for the determination of TYL. In addition, recovery experiments indicated that the recoveries ranged from 92.16 to 108.5% in milk and from 84.12 to 110.5% in honey. Therefore, the developed QB-ICA is reliable for determining TYL in milk and honey. In conclusion, the QB-ICA we developed can be considered an effective and rapid tool for screening TYL in food products.