Construction of G-quadruplex/thioflavin T fluorescent probe for label-free detection of malachite green

Malachite green (MG), owing to its extreme toxicity, is strictly prohibited as a drug in aquaculture across numerous countries. To facilitate an economical and user-friendly strategy for MG detection, we rigorously screened c-MYC22 from a wide range of G-quadruplex (G4) DNAs, aiming to craft a fluorescent probe in tandem with the water-soluble fluorescent dye thioflavin T (ThT). This endeavor culminated in the development of a label-free, rapid and sensitive method for MG detection. The fluorescence of the G4/ThT complex dims significantly when MG interacts with G4, allowing for the quantitative analysis of MG. Our method boasts linear detection ranges between 50-1000 mu g/L and 400-6000 mu g/L, with an impressive limit of detection as low as 6.82 mu g/L and a short detection time of 15 min. The fluorescent probe demonstrates excellent specificity, rendering it ideal for MG detection in real water samples. Furthermore, this method stands out for its simplicity and efficiency, the probe used does not need to be modified, and the detection takes only one step with a short detection time. These features make it a strong contender for commercialization as a method of MG detection, presenting significant potential for further advancement.