The chemiluminescence immunoassay for aflatoxin B1 based on functionalized magnetic nanoparticles with two strategies of antigen probe immobilization.

A rapid and sensitive chemiluminescence immunoassay (CLIA) based on magnetic nanoparticles (MNPs) was developed to detect aflatoxin B1 (AFB1), which is a potent carcinogen in nature. We prepared monodisperse MNPs (300 nm in diameter) according to the solvothermal synthesis reaction and the MNPs were coated with silica by the Stöber method. Triethox was used as a one-step carboxylation reagent, and 3-aminopropyltriethoxysilane (APTES) an amination reagent, to modify the MNPs. We prepared two types of solid phase antigens using the above synthesized functionalized MNPs coupled with the later prepared AFB1-oxime active ester and the purchased BSA-AFB1 respectively. 2',6'-dimethylcarbonylphenyl-10-sulfopropylacridinium-9-carboxylate 4'-N-hydroxysuccinimide (4'-NHS) ester (NSP-DMAE-NHS), as a novel luminescent reagent, was used to label anti-AFB1 antibodies. The two CLIA calibration curves based on the two types of solid phase antigens were obtained and compared. The acquired limit of detection (LOD) was about 0.001 ng/mL for the two functionalized MNPs-based immunoassays, and the half maximal inhibitory concentration (IC50 ) was 0.51 ng/mL for the MNPs-AFB1-based method and 0.72 ng/mL for the MNPs-BSA-AFB1-based method.