Design And Synthesis Of A Novel Near-infrared Fluorescent Molecular Probe And Its Application In Cell Imaging

Heavy metal elements are a common type of environment pollutants,whose content should be monitored strictly in drinking water and food safety and other aspects.Copper is special among them,which is a necessary trace element to maintain the human health,and play an important role in metabolism and nervous system.Copper deficiency and over-intake can cause various diseases,including Alzheimer's disease,Parkinson's disease and Wilson's disease.Thus,the development of a rapid method for copper detection with high sensitive is a very valuable work.Because of its high sensitivity,good selectivity,low cost,simple operation and rapid response,the fluorescence analysis method has been widely used in heavy metal detection in recent years.At present,fluorescence sensors,including quantum dots,metal clusters,carbon dots and organic dyes,have been developed for fluorescent detection of copper ions.Among them,the near-infrared fluorescent sensor has a smaller photodamage to the cells and high tissue penetration,can overcome background fluorescence interference of the biological tissue,especially suitable for cell imaging.In this paper,the divalent copper ions(Cu2+)were detected selectively and sensitively by using semi-cyanine derivative organic dyes with near-infrared emission,and cell imaging for Cu2+ was carried out.There are two chapters in this paper,and the specific content of each one is as described below:In chapter 1,the fluorescence analysis method was systematically described firstly,including the basic principle of fluorescence analysis method and the detection mechanisms of fluorescence analysis method.Then,the research status of fluorescence sensors for detecting Cu2+ was described in detail based on different detection mechanisms.Next,the near-infrared(NIR)fluorescence technique was described,and tthree kinds of materials with NIR fluorescence emission were summerized.Moreover,the applicarions of the materials above in the biological field was briefly introduced.Finally,the topic selection and main research contents were put forward.In chapter 2,a new fluorescence probe(XL-Cu)based on semi-cyanine for Cu2+detection has been synthesized.The fluorescence of the probe could be effectively quenched by Cu2+ because the metal coordination could block up the intramolecular charge-transfer,which was assigned to the dynamic coordination between the o-hydroxy imidazole of the molecular and Cu2+.Based on this mechanism,a new method for sensitive and selective detection of Cu2+ has been developed,with a limit of detection of 14 nM(R2=0.9994).In addition,the maximum emission of the probe located at near-infrared region and,show less phototoxic,more penetrability for biological tissue and lower cytotoxicity,suggesting extensive applications in living imaging.