Label-free fluorescent aptasensing of mycotoxins via aggregation-induced emission dye

Aggregation-induced emission (AIE) dyes now serve as powerful tools for fluorescence analysis and biological imaging due to their light-up property in the aggregated state. Herein, we proposed an AIE dye-based aptasensor, enabling label-free and turn-on detection of mycotoxin. The positively charged AIE dyes would confer high-affinity to negatively charged aptamers and be lighted up by the aggregation process of dye molecules. Attributed to the resistance of ochratoxin A (OTA)-binding aptamer complex to enzyme digestion, label-free analysis of OTA could be realized via the synergetic utilization of AIE dyes and enzymatic digestion process. The digestion process could contribute to a signal to background ratio (S/B) of 1.71 for OTA detection. Remarkably, the adoption of AIE dyes would lead to a dramatic enhancement of over 104.5% of S/B compared to conventional nucleic acid dyes, thus favoring the sensitivity of the aptasensor. Only one aptamer sequence was involved in the assay, thus avoiding the complex structure design of aptamer probes. The AIE dye-based aptasensor could confer a limit of detection of 0.4 ng/mL for OTA detection. Besides, it exerted remarkable specificity for identifying OTA, and has been successfully applied for OTA analysis in wine and coffee. AIE dyes would be a compelling candidate in biohazard screening filed, and the proposed aptasensor would potentially provide a universal platform for on-site detection of food and environment contaminations.