Naked-Eye and Near-Infrared Fluorescence Probe for Hydrazine and Its Applications in In Vitro and In Vivo Bioimaging

Hydrazine has been applied diffusely in most of the chemical industry; however, it is a hazardous environmental pollutant and highly toxic to organisms. Selective, rapid, and sensitive detection of hydrazine thus becomes absolutely necessary in both biological and environmental sciences. Accordingly, fluorescence probes for hydrazine have been paid great attention in recent years. Disclosed here is the near-infrared (NIR) fluorescence probe with a turn-on fluorescent probe CyJ based on the structure–emission property relationships of the NIR dyes containing an acetyl group as the recognizing moiety. This new probe not only can be readily prepared, but also shows excellent sensing properties. First and most important of all, CyJ is highly selective for N₂H₄ over various anions, cations, and other amino compounds and has a low limit of detection (LOD) of hydrazine (5.4 ppb as fluorescence sensor and 6.1 ppb as UV sensor). Besides, CyJ exhibited a dramatic increase in fluorescence at λ_max = 706 nm in the presence of N₂H₄, and it offers a rapid, colorimetric and vapor sensing detection process for N₂H₄ in both aqueous solution and diluted human serum. Furthermore, CyJ has good cell-membrane permeability and low cytotoxicity. In addition, we have successfully applied the CyJ to visualize N₂H₄ in live mouse and, for the first time, in tissues such as the liver, lung, kidney, heart, and spleen.