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Ontario Grain Farmer Magazine

Aptamer development for mycotoxin detection in grains

Principal Investigator

Richard Manderville

Research Institution

University of Guelph

External Funding Partners

This project was funded in part through Growing Forward 2 (GF2), a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of GF2 in Ontario.

Project Start

June 2014

Project End

May 2017

Objectives

  • Incorporate fluorescent DNA bases into ochratoxin A (OTA) and aflatoxin aptamers and optimize mycotoxin detection.
  • Chemically synthesize modified DNA base triphosphates to generate random libraries of aptamers for mycotoxin detection.

Impact

  • The development of affordable hand-held aptamer test-kits for mycotoxin detection in grain dust and in the field.
  • The enhancements of methods to ensure Canadian grain products meet government regulations for mycotoxin levels.
  • The development of potential new methods to ensure food safety in Canada.

Scientific Summary

Mycotoxins are a major health threat to humans and animals and cause substantial economic losses. Aptamers are single stranded DNA or RNA that bind targets with high affinity/specificity and are attractive for developing low-cost, robust sensors for mycotoxin detection. Compared to antibody-based technologies for mycotoxin detection, aptamers are much cheaper to manufacture, are more stable, and can be re-used repeatedly. However, antibodies are comprised of proteins, and have twenty amino acid building blocks, which provide great chemical diversity and specificity for its target; while DNA aptamers have only four building blocks called bases, which limits chemical diversity and specificity for its target. The DNA bases also lack diagnostic features that can be used for detection of target binding. Despite these limitations in DNA bases, DNA aptamers have been used commercially to detect mycotoxins, such as ochratoxin A (OTA) and aflatoxin B1. A goal of our research is to generate modified DNA bases that can provide a unique florescent signal when the aptamer binds the mycotoxin.

Fluorescent aptamers (aptasensors) have been shown to be effective for rapid testing for mycotoxins and show great promise for use commercially in a variety of detection platforms. The Manderville laboratory has synthesized fluorescent DNA bases that can be readily incorporated into DNA aptamers. These bases can be manipulated to provide a fluorescent signal when the mycotoxin binds to the aptasensor and can be used to determine the binding site of the mycotoxin. The change in florescence intensity of the fluorescent probe within the aptamer can be used to detect the amount of mycotoxin in a given sample. Efforts will focus on optimizing aptasensors that bind to OTA and aflatoxin B1 for detection in the field. The modified DNA bases will then serve as new tools for aptasensor development for a wider range of mycotoxins that contaminate grain products.