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ARS Home » Research » Publications at this Location » Publication #62775


item Thompson, Vicki
item Maragos, Chris

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: In this study, a fiber-optic immunosensor was designed and constructed in order to measure fumonisins. Fumonisins are mycotoxins produced by several common fungal contaminants of corn. The fumonisins have been shown to cause disease in horses, swine, and rats, and have been linked with cancer in humans. Several methods have been published for measurement of fumonisins in both corn and corn based foods and feeds, but typically such methods require extensive time-consuming sample preparation and are not suitable for screening of large numbers of samples. The immunosensor developed here was shown to be as sensitive to fumonisins as most currently used methods, was simple to use and was rapid. This technique also shows promise that it will not require the extensive sample preparation that current methods do, and it may be readily adapted to automated analysis for rapid sample screening.

Technical Abstract: A fiber-optic immunosensor was developed to measure fumonisin B1 (FB1). Monoclonal antibodies produced against FB1 were covalently bound through a heterobifunctional silane to a step-etched 800 um core optical fiber. An evanescent wave effect was utilized to excite fluorescein isothiocyanate labeled FB1 (FB1-FITC) molecules near the surface of the fiber. A direct competitive assay was used to measure FB1 concentrations with the following steps: saturation of antibody binding sites by FB1-FITC, competition of FB1 and FB1-FITC with displacement of the labeled toxin, and resaturation of binding sites by FB1-FITC. The signal generated in the assay was found to be inversely proportional to the FB1 concentration. The sensor could be reused for measurement of multiple samples with this format. This sensor exhibited a working range of 10 to 1000 ng FB1/ml, an IC50 of 70 ng/ml and a limit of detection of 10 ng/ml. These values compared favorably with currently available ELISA techniques. The sensor exhibited cross reactivity with fumonisin B2 but did not react to hydrolyzed FB1, sphinganine or tricarballylic acid. This sensor provides a fast, simple assay for fumonisins which is also highly sensitive and specific.