Monitoring isoniazid metabolism in vivousing a near-infrared fluorescent probeElectronic supplementary information (ESI) available. See https://doi.org/10.1039/d2ay00185c

As a strong nucleophilic substance, hydrazine is widely used in the fields of agriculture, industry, and medicine. Hydrazine compounds usually exist as intermediates of some drugs. Many drugs, such as isoniazid and carbidopa, produce hydrazine metabolites. Hydrazine is a genotoxic substance, which can cause DNA lesions and cancer vialong-term exposure. Therefore, it is very important to monitor the level of hydrazine in the human body with high selectivity and sensitivity. Here, we synthesized a near-infrared (NIR) fluorescent probe Cy-HZ based on the hemicyanine skeleton to visualize the metabolism of the drug isoniazid in vivo. The ester group of the probe reacts with hydrazine to generate Cy-H, causing a change in fluorescence. Here, we studied its absorption and fluorescence spectra, the recognition response to hydrazine, the imaging of exogenous hydrazine in cells and the imaging in mice and further applied the probe to monitor the distribution and metabolism of isoniazid.