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United States Department of Agriculture

Agricultural Research Service

Research Project: INNOVATIVE MATERIALS FOR USE IN MYCOTOXIN DETECTION

Location: Bacterial Foodborne Pathogens & Mycology Research Unit

Title: Signal amplification using colloidal gold in a biolayer interferometry-based immunosensor for the mycotoxin deoxynivalenol

Author
item Maragos, Chris

Submitted to: Journal of Food Additives & Contaminants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 26, 2012
Publication Date: June 1, 2012
Citation: Maragos, C.M. 2012. Signal amplification using colloidal gold in a biolayer interferometry-based immunosensor for the mycotoxin deoxynivalenol. Journal of Food Additives & Contaminants. 29(7):1108-1117.

Interpretive Summary: Deoxynivalenol (DON) is a toxin produced by certain species of fungi that can infest wheat, barley, and corn worldwide. Because of this the U.S. conducts extensive monitoring of commodities both for domestic use and export. As part of efforts to improve monitoring of the toxin, a method for detecting DON in wheat using a novel analytical technology, biolayer interfereometry, was developed and compared to an established (chromatographic) method. During development it was discovered that signal from the sensor could be substantially increased through the use of an antibody labeled with colloidal gold. The technique was successfully used to measure DON in samples of naturally contaminated wheat, with results that agreed well with the reference method. The result is a rapid and reusable sensor that can be used to monitor DON in wheat.

Technical Abstract: Deoxynivalenol (DON) is a toxin produced by certain species of fungi that can infest wheat, barley, and corn. The fungi cause diseases in crops worldwide and some of the secondary metabolites, such as DON, can adversely affect animal health and food safety. To rapidly monitor DON in wheat a biosensor using the principle of biolayer interferometry (BLI) was developed. Signal from the sensor was substantially amplified through the use of a primary antibody-colloidal gold conjugate. The amplification was much greater in the presence of wheat matrix than in buffered solution, suggesting matrix components may have contributed to the enhancement. The improved signal provided by the amplification allowed for the development of rapid qualitative and quantitative assays. The limit of detection of the method was 0.09 mg/kg and the limit of quantitation was 0.35 mg/kg. Recovery from wheat spiked over the range from 0.2 to 5 mg/kg averaged 103% (RSD 12%). The quantitative assay compared favorably (r2 = 0.9698) to a reference chromatographic method for 40 naturally contaminated wheats. The qualitative assay was able to accurately classify the same group of samples as either above or below a 0.5 mg/kg threshold. These results suggest that the BLI technique can be used to rapidly measure DON in wheat.

Last Modified: 9/2/2014