Development of dimeric aptamers for highly specific recognition of patulin and a label-free fluorescence aptasensor...

The directional design of multivalent aptamers significantly impacts the development of aptamer-mediated rapid detection methods. In this study, ten kinds of dimeric aptamers were designed using different flexible linkers. The dimeric aptamer of 1AS2 with the "A" base spacer demonstrated the best fluorescence activity and binding activity for patulin when combined with the fluorescence probe of thioflavin T (ThT). A label-free fluorescence aptasensor for patulin detection was developed based on the G-quadruplex/ThT platform using the dimeric aptamer of 1AS2. This fluorescence aptasensor had a wide detection range of 0.5-200.0 ng/mL for patulin within the operation time of 10 min and showed negligible cross-reactions with common mycotoxins. The assay exhibited good recoveries of 85.3 % ∼ 99.3 % in juice samples by the aptasensor, and the results were validated by HPLC analysis with good correlations. This study brings a new strategy for generating multivalent aptamers and label-free aptasensors for the accurate detection of food contaminants.