An Improved Chemiluminescence Immunoassay for the Ultrasensitive Detection of Aflatoxin B1

An indirect competitive chemiluminescence (CL) immunoassay based on Fe3O4@SiO2@Au magnetic nanoparticles (Au-SCMPs) has been optimized and developed for the detection of aflatoxin B1 (AFB1). To improve the detection sensitivity and efficiency, this method combines 2′,6′-dimethylcarbonylphenyl-10-sulfopropyl acridinium-9-carboxylate 4′-NHS ester (NSP-DMAE-NHS) as a new kind of high efficient luminescence reagent with a simplified separation procedure based on the optimized Au-SCMPs. Superparamagnetic nanoparticles were coated with different sizes of Au colloids (18, 30, and 50 nm), and their capacities in immobilization of bovine serum albumin (BSA) were investigated. The BSA-AFB1 conjugate (BSA-AFB1) was immobilized on the optimized Au-SCMPs and competed with the free AFB1 for specially binding the NSP-DAME-NHS-labeled anti-AFB1 antibody (mAb-AFB1). After the indirect competitive immunoreactions and magnetic separation, the CL of the nanoparticles was measured by a homemade luminescent measurement system. Under the optimum conditions, the IC50 value was 0.07 ng mL−1 and the limit of detection (LOD) of AFB1 was 0.01 ng mL−1, respectively. The result shows a much lower IC50 and LOD than that typically achieved by ELISA. This proposed immunoassay method was rapid, low-cost, and suitable for the detection of AFB1.