Pseudo-color-assisted aggregation-induced emission dye biosensor for "label-free" monitoring of ochratoxin A signals in plants.

Ochratoxin A (OTA) is a fungal toxin that is highly toxic and widely distributed, causing serious damage to important economic crops. Understanding their presence in plants can help protect economic crops from infection. In this work, a "label-free" OTA sensing probe that directly uses aptamer sequences to achieve targeted response was prepared. The aptamer hybridized with cDNA can resist digestion by exonuclease (EXO.I), while the presence of OTA competes with the aptamer and disrupts the resistance process. The entire sensing process can be monitored by the fluorescent indicator aggregation-induced emission dye (QAFI). The sensing method has a detection limit of 17 pM and a linear range of 0.05-150 nM. This fluorescent probe can not only perform on-site analysis of OTA in vitro, but can also be easily incubated into plants for fluorescence monitoring. More importantly, in view of the problem that the single-color presentation of traditional fluorescence images is not easy to observe, this work uses Java algorithms to develop a pseudo-color one-key conversion applet. This greatly saves researchers time in analyzing images. On this basis, this work explores the characteristics of OTA infection in plants under various physiological states, which has a certain reference significance for the planting and cultivation of crops.