A coumarin-based fluorescent probe for sequential recognition of zinc ion and nitric oxide, and its applications in real water sample, fluorescence anti-counterfeiting and bioimaging in vivo.

Zinc (Zn), as an essential trace element in organisms, plays an indispensable role in a series of physiological processes. Similarly, nitric oxide (NO) is an important signaling molecule that is involved in many biological processes. The imbalance of Zn2+ and NO levels in organisms could give rise to various related diseases, so it is very significant for the detection of Zn2+ and NO. Herein, a novel fluorescent probe (ASZ) was constructed for the sequential response to Zn2+ and NO using coumarin as fluorophore and aminotetrazole as recognition group. In the presence of Zn2+, the weak green fluorescence of probe ASZ was obviously enhanced because of the inhibition of PET effect. The PET effect of the system was turned on when NO was added to the generated probe ASZ-Zn2+ and resulting in the complete quenching of the fluorescence. The detection limits (LODs) of Zn2+ and NO by probe ASZ were 9.94 nM and 16.8 nM, respectively. Probe ASZ was used for detecting Zn2+ in practical water sample and the study of fluorescence anti-counterfeiting. Furthermore, probe ASZ was successfully applied to bioimaging of exogenous Zn2+ and NO in mice due to its high sensitivity, fast response and low cytotoxicity. Therefore, probe ASZ can provide a new method for understanding the physiological and pathological effects of Zn2+ and NO and environmental monitoring.