A dual-emission fluorescence probe for the detection of viscosity and hydrazine in environmental and biological...

The microenvironments of biological systems are associated with the pathology of organisms. This study, aimed to construct a hemicyanine-based probe (1), which can respond to mitochondrial viscosity and hydrazine (N₂H₄), for imaging application in living cells and zebrafish. The probe showed no fluorescence due to the intramolecular rotation in the solution; however, it exhibited a strong emission at 730 nm when the molecules were restricted to a high-viscosity environment. The addition of N₂H₄ caused an elimination reaction of the N-substituted group in the pyridinium part and further broke the CC bond to produce a highly fluorescent hydrazone. Also, the probe could selectively and quantitatively detect N₂H₄ via the fluorescence enhancement at 510 nm in a concentration range of 0 μM-140μM, with the limit of detection being 0.0485 μM. This probe may be used to study diseases related to N₂H₄ and viscosity changes in biological systems. Furthermore, the analysis methods based on probe 1 for N₂H₄ detection in soil, water, and air samples were successfully established.