Magnetic Nanoparticle Based Immunofluorescence Assay for the Determination of Aflatoxin B 1

A rapid and sensitive immunofluorescence assay for aflatoxin B1 (AFB1) determination was developed using magnetic nanoparticles (MNPs). MNPs were prepared by thermal co-precipitation of Fe2+ and Fe3+ in aqueous solution. MNPs were functionalized with (3-aminopropyl)triethoxysilane. An optimum amount of polyclonal anti-AFB1 antibody was immobilized on MNPs (40 μg/mg MNPs). Fluorescein isothiocyanate (FITC) conjugate of AFB1 was prepared. A competitive immunoassay of AFB1 was performed. AFB1 in the sample and AFB1-FITC fluorescent conjugate competed for binding to the immobilized antibody on MNPs. The magnetic nanoparticles were removed using a permanent magnet. Fluorescence intensity of the unbound conjugate AFB1-FITC in the supernatant was measured. The excess of the conjugate is directly proportional to the concentration of AFB1 in the sample. The developed method is very rapid (30 min) and sensitive with the limit detection for AFB1 of 0.9 pg/mL and linear range of 1–100 pg/mL.