A versatile and cost-effective aptamer-based fluorescence quenching assay is described for the detection of the mycotoxin zearalenone (ZEN). Exfoliated functional graphene oxide (FGO) of high water-dispersibility is adopted as an effective fluorescence quencher of the fluorescence of FAM. Quenching properties of graphite, graphene oxide (GO) and FGO were investigated, and FGO is found to be the most efficient quencher. FGO therefore was used in an aptamer-based detection format that allows ZEN to be determined in the concentration range of 0.5 to 64 ng·mL−1 with a limit of detection of 0.5 ng·mL−1. The aptamer assay has good repeatability and reproducibility (n ≥ 4). Selectivity of the aptamer assay against a set of possible interferents is substantiated. This aptasensing assay was successfully applied to the determination of ZEN in (spiked) alcoholic beverage samples, beer and wine, and recovery values in the range of 87 to 96% were obtained for the determination of ZEN at levels as low as 1–16 ng mL−1.
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