Colloidal gold-based immunochromatographic strip assay for the rapid detection of diminazene in milk
2020
Chen, Linlin | Sun, Yaning | Hu, Xiaofei | Xing, Yunrui | Kwee, Sharon | Na, Guanqiong | Zhang, Gaiping
Diminazene (DIM) is widely used to treat trypanosomiasis in livestock, but its residues in animal products can cause food safety problems. Thus, a rapid colloidal gold-based immunochromatographic strip assay was established to analyse DIM residue in milk samples. A highly sensitive and specific monoclonal antibody (mAb) against DIM was produced with a new synthetic immunogen by the active ester method. The titre of the prepared antibody was up to 1:1.0 × 10⁶, the affinity constant was 2.2 × 10⁸ L mol⁻¹ and the half-maximal inhibitory concentration (IC₅₀) was 0.4 ng mL⁻¹ based on enzyme-linked immunosorbent assay (ELISA). Then, the colloidal gold-labelled mAb probe was successfully prepared and used for preparing the immunochromatographic strip. The strip showed high sensitivity and specificity, the IC₅₀ for DIM was 5.2 ng mL⁻¹, the limit of detection was 1.2 ng mL⁻¹ and the linear range of detection was 1.8–15.4 ng mL⁻¹. The average recoveries ranged from 89.5% to 91.7%, and coefficients of variation were 6.6–7.2%. The immunochromatographic strip assay can be employed in the rapid detection of DIM residue in milk samples.
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