A novel protein-based supramolecular recognition approach for ratiometric fluorescence detection of fipronil

Fipronil, a wildly used pesticide, exhibits high toxicity to pollinators, aquatic organisms, farmland birds, as well as mammals that have GABA receptors, including humans. Thus, developing an effective method for fipronil determination is of great importance. Although the fluorescence assays have the features of easy-to-use, rapid response, high sensitivity and visualized readout, such assay for fipronil was rather difficult to design because fipronil was both chemically and photophysically stable. Herein, we utilized a chalcone dye bound into albumin inner-cavity to construct a novel supramolecular recognition system, for the first time, successfully realizing ratiometric fluorescence detection of fipronil. The sensing mechanism has been carefully verified by the molecular docking, fluorescent titration, DLS tests and fluorescence lifetime. This reported probe could detect fipronil with a rapid response (< 3 min), high sensitivity (LOD similar to 0.01 ppm) and selectivity, good anti-interference property, and significantly, ratiometric color change from green to yellow, which could be discriminated by naked eyes. Moreover, we demonstrated the application of this method in the ratiometric tracking of fipronil in plants (Arabidopsis thaliana). We anticipate this albumin-based supramolecular recognition system would inspire more probe design for environmental monitoring.

Automated summary

In this study, a supramolecular recognition system based on a dye bound to albumin was used to detect fipronil. The method allows for ratiometric fluorescence detection with a rapid response, high sensitivity, and selectivity, and the color change can be observed by naked eyes. This method was successfully applied for tracking fipronil in plants.