Submitted to: Clinical Ligand Assay Society National Meeting
Publication Type: Proceedings
Publication Acceptance Date: March 27, 1997
Publication Date: N/A
Technical Abstract: A fiber-optic immunosensor was used to determine concentrations of the mycotoxin fumonisin B1 (FB1) in both spiked and naturally contaminated corn samples. Monoclonal antibodies produced against FB1 were covalently bound through a heterobifunctional silane to an etched 800 um core optical fiber. An evanescent wave effect was utilized to excite fluorescein isothiocyanate elabeled FB1 (FB1-FITC) molecules near the surface of the fiber. A direct competitive assay was used to measure FB1 concentrations. The signal generated in the assay was found to be inversely proportional to the FB1 concentration, with an IC50 of 70 ng/mL and a limit of detection of 10 ng/mL. Corn samples were extracted with a mixture of methanol/water. Two methods were used to prepare the methanolic corn extracts before introduction to the immunosensor: 1) simple dilution of the methanolic corn extract; or 2) affinity column cleanup. Simple dilution of methanolic corn nextracts yielded an assay with an IC50 equivalent to 25 ug FB1/g corn and limit of detection of 3.2 ug/g corn, while affinity column cleanup of corn extracts yielded an assay with an IC50 of 5 ug FB1/g corn and a limit of detection of 0.4 ug FB1/g corn. Naturally contaminated corn samples were also analyzed after either simple dilution or affinity column cleanup. For comparison, the naturally contaminated corn samples were analyzed with an HPLC method. The HPLC method and the immunosensor method agreed well except when large amounts of other fumonisins that cross-react with the immunosensor (i.e. fumonisin B2) were present. The immunosensor has the potential to rapidly screen individual corn samples for fumonisins.