A sensitive cytometric bead array for chlorpyrifos using magnetic microspheres

Chlorpyrifos is an organophosphorus pesticide widely used in agriculture and known to cause environmental pollution, as well as negatively impact human health. In this study, we reported a cytometric bead array (CBA) method to detect chlorpyrifos. Magnetic microspheres (Fe3O4@SiO2-COOH) were prepared and coupled with chlorpyrifos-BSA. Flow cytometry was then used to perform an indirect competitive immunoassay to detect chlorpyrifos residue. CBA is based on the use of three-dimensional magnetic microspheres and allophycocyanin-conjugated goat-anti-mouse secondary antibody (APC-IgG-SecAb), effectively avoiding interfering from the matrix. The results showed that this assay requires only 15 s for a single run. Furthermore, CBA was shown to have a detection limit of 1.09 ng mL(-1)and an IC50 of 15.95 ng mL(-1). This detection limit value is approximately three times lower than that of ELISA, and the working range for chlorpyrifos detection covers three orders of magnitude. This study indicates that CBA method is a promising detection method with widespread utility for food safety and environmental monitoring.