Aptamers are single-stranded oligonucleotides with the ability to bind tightly and selectively to a target analyte. High-affinity and specific aptamers for a variety of mycotoxins have been reported over the past decade. Increasingly, these molecular recognition elements are finding applications in biosensors and assays for the detection of mycotoxins in a variety of complex matrixes. This review article highlights the mycotoxin aptamers that are available for mycotoxin detection and the array of biosensing platforms into which they have been incorporated. Key advantages that aptamers have over analogous technology, and areas in which these advantages may be applied for the benefit of practical mycotoxin detection, are also discussed.

Aflatoxins are a class of mycotoxins that are of great agro-economic importance.Their severe acute and chronic health effects have made them of great concern from a public health perspective as well. Due to their health implications, and large economic burden, aflatoxins have become the most studied group of mycotoxins. A specific interest in rapid, robust, and cost effective, on-site sensing platforms for mycotoxin contaminants has been shown. Aptamers are functional oligonucleotide sequences that are selected to bind a cognate ligand with high affinity and selectivity. Novel structure switching aptamer candidates for total aflatoxin were previously selected. The selection was performed using two template designs. Electrophoretic mobility shift assays, melting temperature studies, and circular dichroism along with predictive structural characterization techniques were used to help elucidate the aptamer candidate's structural biases for G-quadruplex formation. Two candidates were determined to bind aflatoxin B1 (AFB1) with high affinity using microscale thermophoresis. Sequences DZA3 and 3MR5 had reported dissociation constants (Kd) for AFB1 of 42.1 ± 23.8 nM and 1.4 ± 6.7 μM, respectively. Using the AFB1 binding aptamers, progress has been made towards developing FRET-based signalling sensors that leverage the structure-switching properties of the aptamer.iii

Food safety is a growing public health concern worldwide. The need to detect unsafe levels of food contaminants such as chemical compounds, toxins and pathogens prompts new technology and advances in biosensing for food safety. Although current detection methods are able to detect such contaminants with a high level of selectivity and sensitivity, these methods continue to lack practical application. A reliable, easy-to-use, inexpensive detection method that can be used quickly and on-site is a necessity, especially for contaminants that primarily affect food commodities in developing countries. Aptamers are single-stranded oligonucleotides capable of binding a specific target molecule with a high degree of affinity and selectivity. These molecular recognition elements can be selected to bind selectively to a specific target molecule, ranging from small molecules to whole cells. This allows aptamers to be used as the recognition components for food-safety related biosensors. This chapter will review recent literature in aptamers for food-safety related target molecules, and will focus on the incorporation of these aptamers in sensitive and practical biosensors for a variety of food products.