A new benzothiazoloacetonitrile-derived fluorescent probe for selective hydrazine detection and its applications in bioimaging and cotton swab analysis

Hydrazine (N₂H₄) is extensively utilized in various chemical industries. However, it is a highly toxic and explosive chemical posing a serious risk to human health and the environment, which warrants its quick and selective detection. To address this issue, we introduce a benzothiazoloacetonitrile-based fluorescent probe containing a recognition site for hydrazine detection. Adding the benzothiazoloacetonitrile group to the phenanthroline-based imidazole fluorophore increased BTN's electrophilicity, aiding the nucleophilic attack by hydrazine. This led to a rapid fluorescence change from orange to green within one minute, with a limit of detection (LOD) of 0.21 µM, resulting from the cleavage of the olefinic bond between the donor and acceptor units. The probe's selective response to hydrazine was supported by a specific reaction mechanism, confirmed by LC-MS and DFT studies. Additionally, the probe can detect hydrazine using cotton swabs for quick, on-site testing. It also allows for clear visualisation in living cells through different fluorescence channels. Overall, these results demonstrate that the probe exhibits significant potential for the detection of hydrazine in environmental and biological samples.