Rapid detection of fluoroquinolone residues in aquatic products based on a gold-labeled microwell immunochromatographic assay. (7th May 2022) - Xiao, Jiaxu
Abstract: Objectives: Fluoroquinolones (FQs) are widely used in aquaculture, and their residues have caused many problems threatening human health. Here, this study aims to develop a colloidal gold immunochromatographic strip based on gold-labeled microwells to screen the residues of FQs on site. Materials and methods: The Protein A Magarose Beads affinity chromatography method was adopted to purify the ascites against FQs. By using a strategy of heterologous coating antigen, different coating antigens are applied to detect FQs. The gold-labeled microwell immunochromatographic assay was used to improve the sensitivity of the test strip by the advanced reaction of antigen and antibody. Results: The antibodies were verified to be of high purity up to 99%, and the titer reached 1:1 024 000. The combination (enoxacin-OVA and the antibody) detected the 4 banned FQs (pefloxacin, PEF; norfloxacin, NOR; lomefloxacin, LOM; ofloxacin, OFL) with the 50% inhibiting concentration (IC50 ) values ranging from 1.3 to 2.1 ng/mL and cross-reactions ranging from 67.3% to 106.1%. The analysis of spiked crucian carp, silver carp, grass carp, and shrimp samples showed that the limit of detection for PEF, NOR, LOM, and OFL was 4 μg/kg. A comparative study with liquid chromatography tandem mass spectrometry (LC-MS/MS) demonstrated that the assay provided an effective screening tool for the rapid detection of FQs residues. Conclusions: The results indicated that the test strip can realize full coverage recognition of the 4 banned FQs and has good accuracy, specificity, reproducibility, and stability; therefore, they are more suitable for rapid detection of FQs in aquatic products.