A magnetic nanoparticle-based lateral flow immunochromatography assay for the rapid detection of fluoroquinolones in milk

A magnetic nanoparticle (MNP)-based lateral flow immunochromatography assay (LFIA) was established to detect fluoroquinolones (FQs) in milk. This method is an improvement of traditional Au nanoparticle (AuNP)-based LFIA. Compared with AuNP-labeled antibody, the combination between MNPs and antibody is stronger and more stable, and the preparation process is convenient. In this study, the color intensity of MNPs-LFIA test strip was analyzed, which laid a research foundation for magnetic quantitative analysis and high sensitivity analysis of LFIA. The limits of detection (LODs) for 10 FQs in phosphate buffer (PB) solution ranged from 1 to 5 ng/mL, and in milk ranged from 2 to 20 ng/mL. The recovery in spiked milk sample ranged from 16.47 to 83.67%. The log functions of analyte concentration and T/C value were fitted into a linear equation. The specificity of the MNPs-LFIA is satisfactory, without cross-reaction with antibiotics from other chemical classes. The results of this method are consistent with those of ultra-performance liquid chromatography-mass spectrometry, indicating the MNPs-LFIA method is reliable and accurate. As far as we know, this is the first time that MNPs-LIFA has been applied to the detection of FQs in milk.