Development of Ultrasensitive Electrochemical Biosensors for Aflatoxins Group
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Date
2019-04-04
Department
Chemistry
Program
Master of Science
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Abstract
Aflatoxins (AF) are secondary metabolites produced naturally by molds, primarily the Aspergillus flavus, Aspergillus parasiticus and Aspergillus nomius fungal species. They are widely spread and are major contaminants in agricultural food commodities such as peanuts, cereals, corn, sesame seeds, sunflower seeds, tree nuts, and many more, and can enter egg, meat and dairy products through animal feeds. Aflatoxins are extremely toxic and carcinogenic. Conventionally aflatoxins are detected using Gas Chromatography (GC) and High-Pressure Liquid Chromatography (HPLC) thanks to their high sensitivities. However, they also require expensive instruments, highly-trained
personnel, and time-consuming sample pre-treatment and pre-concentration. Therefore, fast, ultra sensitive assays and biosensors based on antibody-antigen actions are being developed for rapid on-site detection of aflatoxins. In these, antibodies that bind specifically and strongly to aflatoxins are used as receptors and are often times immobilized on a solid base; different signaling units may be applied to report the binding event when aflatoxins are present in the sample and are bound to the antibodies. The most common reporting signals are optical and fluorescent techniques. Here we propose to take advantage of the well-established techniques of signal-amplification in electrochemistry. We immobilized an aflatoxin-capturing aptamer and a redox enzyme (horseradish peroxidase) in a hydrogel made by crosslinking the redox polymer, PVIs, on an electrode surface to develop portable, ultra-sensitive aflatoxin electrochemical biosensors. The results show that the biosensor is extremely sensitive, and the detection is fast. (Supported by ASCEND)