Colloidal gold-based immunochromatographic strip assay for the rapid detection of diminazene in milk

ABSTRACT

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.

Graphical Abstract

KEYWORDS:

• Diminazene
• monoclonal antibody
• immunochromatographic strip
• milk

Disclosure statement

No conflict of interest was declared by the authors.

Additional information

Funding

This word was supported by the National Key Research and Development Project [grant number 2018YFC1602903]; China Postdoctoral Science Foundation [grant number 2018M632778]; the National Science & Technology Pillar Program of the 12th Five-Year Plan [grant number 2014BAD13B05]; and the Special Fund for Scientific Research and Development of Henan Academy of Agricultural Science [grant number 2019CY04].