Design And Synthesis Of The Hepatocyte-targeting Nitric Oxide Fluorescent Probe And Its Application In Bioimaging

Nitric oxide (NO) is an important biological messenger molecule, it plays an important role in the physiology and pathology, at the same time NO is generated from the oxidation of L-arginine under nitric oxide synthase (NOS). The disorder of NO can cause a variety of diseases. For example it will cause atherosclerosis and hypertension in the cardiovascular systems. In the nervous systems, NO is very important to brain maturation and development, learning, memory and other aspects, when the release of NO is excessive, it can cause alzheimer and parkinson. In the immune systems, NO can act as the role of antivirus and sterilization. Not only does NO can protect against the invasion of the microbe or bacteria, but also hinder the spread of cancer cells. At the same time the release abnormal of NO in the liver can cause various of hepatic diseases, such as liver fibrosis, cirrhosis, liver cancer and other diseases. To better understand the functions of NO in physiological and pathological, It is urgent to monitor the lever of NO with sensitivity and quantitative technology in biological systems (such as living cells, liver and other deep tissue). So monitoring the NO of the liver is very important to physiology and pathology. Compared to traditional detection methods, fluorescence sensor is widely used in the fields of chemistry, materials, biology and medicine because of its high sensitivity, good selectivity and low detection limit. There are some mitochondria-targeting and lysosome-targeting fluorescent probes for detecting NO, but no liver-targeting fluorescent probes for monitoring NO have been reported. However, the normal content of NO in liver closely linked to hepatic tissue. The mechanism of action of NO in liver has remained unraveled, mainly because of the lack of liver-targeting fluorescent probe for monitoring NO.In view of the foregoing, we have designed a liver-targeting fluorescent probe for monitoring NO, the reporter of the fluorescent probe is rhodamine B, at the same time o-phenylenediamine act as the recognition moiety, and galactose serves as the liver-targeting group. The fluorescent probe has a very good water solubility, the probe is selective towards NO, hence fluorescent probe can be used to detect NO. In the present of NO, o-phenylenediamine moiety of fluorescent probe Gal-RhB cleaved from the probe. So rhodamine will transform into the open-ring form, thus strong emission occurs.The water-soluble fluorescent probe of Gal-RhB can monitor NO with high selectivity and stability under different pH values. At the same time the response is very fast, and the reaction is completed in 7 minutes. When the concentration of NO ranges from 0 to 500 nM, good linear response can be obtained and the detection limit is 1.62 nM.MTT cytotoxicity experiments show that the probe of Gal-RhB is low cytotoxicity which can be used for imaging in living cells. Fluorescence imaging results showed that the probe is able to target hepatic cells and detect NO in the liver. Zebrafish imaging shows that the fluorescent probe can target hepatic tissue of the zebrafish for monitoring NO. It also has a deeply significance for further studying of the mechanism of NO in the hepatic tissue.