Magnetic microspheres-based cytometric bead array assay for highly sensitive detection of ochratoxin A

Accurate and sensitive quantification of a specific class of mycotoxins at trace levels in complex matrices with greener approaches is of significant importance. In this study, a green and economical protocol of magnetic microspheres-based cytometric bead array (CBA) assay on indirect competitive principle was developed for sensitive and rapid detection of ochratoxin A (OTA) in malts with a small number of standard and sample solutions. The protocol included the competition of OTA in malt samples and that covalently coupled on the surface of microspheres with its monoclonal antibodies, the separation and aggregation of the magnetic microspheres, and the fluorescence detection of fluorescein isothiocyanate labeled goat anti-mouse immunoglobulin G probes. The magnetic microspheres-based CBA assay allowed for ultralow limit of detection (0.025-mu g kg(-1)) for OTA and showed higher sensitivity compared with the common polystyrene beads-based CBA method. This is the first report on the magnetic microspheres-based CBA assay by using a simple and easy to-operate magnetic separator for highly sensitive and rapid detection of OTA in complex malt samples. By consuming less solvent, time and cost, as well as fewer standard and samples, the developed green protocol expressed high potential for one-site real-time detection of trace components in complex matrices.