Development of a Colloidal Gold Immunochromatographic Strip for Rapid Detection of Fluoroquinolones in Milk

Abstract

Fluoroquinolones (FQs) are widely used in animal husbandry for the prevention of variety of animal diseases. However, if the residues of FQs in animal products that exceed safe limits may pose a serious threat to human health. Therefore, the development of colloidal gold immunochromatographic test strips with high specificity and high sensitivity is crucial for the accurate detection and management of such antibiotic residues. In this study, a monoclonal antibody (mAb) with high specific reactivity to FQs was prepared, which exhibited cross-reactivity with more than 10 fluoroquinolones. The mAb showed that the half-maximal inhibitory concentration (IC₅₀) for PEF was 0.023 ng/mL, with a linear range from 0.0103 to 0.069 ng/mL. A competitive enzyme-linked immunosorbent assay (ic-ELISA) was established. The recoveries of PEF ranged from 80% to 120%, and the average coefficient of variation was below 10%. Based on this mAb, an immunochromatographic test strip for the detection of FQs residues in actual milk sample was developed. The results demonstrated that the test strip could simultaneously detect 12 fluoroquinolones, with a LOD of 1-10 ng/g. This study highlights that establishing a method capable of simultaneous broad-spectrum screening and high-sensitivity detection is essential for effectively monitoring fluoroquinolone residues and ensuring consumer safety.