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

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. [Display omitted] •A dual˗emission fluorescent probe toward N2H4 and viscosity was developed.•The probe exhibited a maximum emission peak at 730 nm for detecting viscosity.•The probe responded to N2H4 via the fluorescence enhancement at 510 nm with the limit of detection being 0.0485 μM.•Analysis methods based on the probe for N2H4 detection in soil, water and air samples have been established.•The probe has been successfully used for monitoring mitochondrial N2H4 and viscosity in the cells and zebrafish.