One-step icELISA developed with novel antibody for rapid and specific detection of diclazuril residue in animal-origin foods.

Diclazuril, a broad-spectrum anticoccidial drug, may be accumulated in edible tissues of animals through illegal use, which poses potential threats to human health through the food chain. In this study, an innovative hapten was designed and an immunogen of diclazuril was successfully synthesised with keyhole limpet haemocyanin as carrier protein; then a monoclonal antibody with high specificity was obtained. Furthermore, based on the novel antibody, a one-step indirect competitive enzyme-linked immunosorbent assay (icELISA) was established for rapid and specific detection of diclazuril residues. Compared with the traditional icELISA method, this method saves at least 0.5 hours and one washing step. Under the optimal conditions, the one-step icELISA for diclazuril exhibited good performance with a 50% inhibition concentration (IC50) value of 0.952 μg/kg. The average recoveries of the icELISA ranged from 73.1% to 115.5% with the coefficient of variation lower than 12.7%, which was evaluated by detecting spiked animal-origin food samples. Finally, the one-step icELISA shows a good correlation with an ultra-high liquid chromatography-tandem mass spectrometry method. Those results demonstrate that the one-step icELISA developed for diclazuril detection is time-saving, low-cost, specific, sensitive, and reliable. It shows good potential for social, environmental, and economic benefits in future use.