Design of a red-emitting camphor-derived benzothiazole ratiometric fluorescent probe for hydrazine detection in environmental samples and its versatile imaging applications in live cells, zebrafish and Arabidopsis thaliana.

Hydrazine (N2H4) has been extensively utilized during industrial production, while its excessive usage presents substantial risks to human health and ecological systems. In this paper, a new red-emitting camphor-derived benzothiazole-based ratiometric fluorescent probe BTMI-AC was synthesized for selectively and sensitively detecting N2H4 with the large Stokes shift of 223 nm. BTMI-AC exhibited a remarkable fluorescence emission shift from 506 nm to 613 nm after reaction with N2H4, and its ratiometric fluorescence signal ratio (I613/I506) showed a favorable linear relationship with N2H4 concentration with the detection limit as low as 33 nM. The quantitative determination of N2H4 in different soil samples was achieved by using BTMI-AC, suggesting its potential application in the on-site monitoring of N2H4 pollution in the environment. BTMI-AC was also immobilized onto test strips and hydrogel matrices to fabricate the portable solid-state sensing platforms for rapid and visual detection of gaseous and liquid N2H4 through the distinct fluorescence color changes from green to red. Moreover, BTMI-AC was employed for tracking the exogenous concentrations of N2H4 in the live cells, zebrafish and Arabidopsis thaliana. Considering that the metabolism of antituberculosis drugs such as isoniazid (INH) may increase N2H4 levels by enzyme induction and bring potential biological toxicity risk, BTMI-AC could successfully realize the fluorescence imaging of endogenous N2H4 distribution in live cells and zebrafish. We expected that BTMI-AC can offer a sensitive, visual and multi-scenario applicable analytical tool for monitoring N2H4 levels in the environmental samples and biological systems.