The Construction Of Near-infrared Fluorescent Probe Based On Cyanine And Thier Application In Tumor Imaging

Regardless of the level of human development,cancer is an important cause of morbidity and mortality worldwide.However,if cancer is detected early,many people can be rescued.Sensitive and selective find of cancer markers is a challenge for early diagnosis of cancer.In this paper,three types of near-infrared fluorescent probes were constructed to detect pH,Cys and H₂S and were successfully used for tumor imaging.1.This paper first designed and synthesized a NIR fluorescent probe for pH detection,named Cy O.This probe has a simple structure,and has a very high sensitivity to H⁺.In addition,the acidic environment can induces the protonation of the probe to produce another compound,named Cy OH,which leads to increased fluorescence in the NIR region.When the pH value was from 7.4 to 5.0,the near-infrared fluorescence increased by 20 times.And there is a good linear relationship between fluorescence intensity and pH.In particular,the probe can detect the pH in various biological samples,such as cells,tissues and living animals,and thus distinguish between normal and cancer environments.This provides some useful basic information for the early diagnosis of cancer.2.On the basis of the previous work,we found that only detecting a single biomarker to achieve early diagnosis of cancer will lead to"false positive"signals in complex biological systems.Therefore,this paper selected two concurrent biomarkers（overexpressed Cys and low intracellular pH）in cancer,and synthesized a NIR fluorescent probe Cy Ac for accurately diagnosing cancer in vivo by sequential detection of Cys and H⁺.Cy Ac can sequentially monitor Cys and H⁺in cells,Cy Ac can sequentially monitor Cys and H⁺in the cell,so that it can distinguish between normal cells and cancer cells.Due to the NIR fluorescence emission,the probe can also distinguish tumor mice from normal mice.It is worth noting that the probe can sequentially detecting two cancer markers,which has certain practical significance for the accurate diagnosis of early cancer.3.Based on Heptamethine cyanine dyes,this paper designed and synthesized a new NIR fluorescent probe Cy O-DNP for sequential detection of H₂S and pH.In this probe,we choose the 2,4-dinitrophenyl（DNP）ether moiety as the recognition group.However,upon interaction with H₂S,Cy O-DNP can release compound Cy O,and the large fluorescent signals can be observed.At the same time,Cy O can further react with H⁺and emit new fluorescence in the new near-infrared region.Moreover,only the co-existence of H₂S and H⁺can release the final near-infrared fluorescence,and the existence of a single substance cannot induce emission.In addition,Cy O-DNP is highly sensitive to H₂S from the very beginning.Due to the unique properties of Cy O-DNP,we applied it in living cells to image H₂S and H⁺.