A dual-response fluorescent probe for N2H4 and viscosity in living cells and zebrafish to evaluate liver injury

Hydrazide drugs can cause severe drug-induced liver injury owing to the enzymatic release of N₂H₄ in the liver. Also, changes in cellular viscosity are associated with liver damage. Thus, simultaneous monitoring of changes in N₂H₄ levels and viscosity can be used to evaluate the side effects of hydrazide drugs. Herein, we firstly reported a near-infrared fluorescent probe (FNN), which contains 1,8-naphthalimide as the fluorophore and a chalcone moiety as the responsive receptor, for sensitively detecting intracellular viscosity and N₂H₄. FNN showed a fast 'turn-on' fluorescence response to N₂H₄ with excellent selectivity. Additionally, FNN could selectively track viscosity without interference from polarity, pH, and other active species. Furthermore, imaging experiments suggested that FNN could be successfully applied in living cells and zebrafish larvae and embryos, which is of great importance for effectively assessing the degree of liver injury.