Design,Synthesis,and Application Study Of Fluorescent Probe For Sensing Cyanide,as Well As Fluorescent Probe For Simultaneously Discriminating Hypochlorite And Singlet Oxygen

Cyanide is a highly toxic reagent,which can cause death in a small dose.However,many food crops can produce endogenous cyanide by decomposing cyanogen glycosides.Eating these improperly processed food crops will lead to chronic or acute cyanide poisoning,which will bring serious harm to the health of consumers.Therefore,it is necessary to develop an accurate quantitative analysis method to detect the cyanide content in food samples in real time.Hypochlorite（ClO^-）and singlet oxygen（¹O₂）are commonly coexisted in living system,and exert important interplaying roles in many diseases.To dissect their complex inter-relationship,it is urgently required to construct a fluorescent probe that can simultaneously detect ClO^-and ¹O₂in living organism.Currently,fluorescent probe has attracted a great deal of attention due to it is suitable for imaging molecules of interest in biological samples and food samples with high spatial and temporal resolution.Therefore,in this thesis,we have developed a ratiometric near-infrared fluorescence probe which can accurately and quantitatively detect cyanide in food samples and a dual-functional fluorescence probe which can simultaneously detect ClO^-and ¹O₂ in living organisms.The specific research contents are as follows:1.A ratiometric near-infrared fluorescence probe for the accurate and quantitative determination of cyanide in food samples.In this probe,coumarin is used as the fluorophore.By increasing the conjugation degree of the probe,the fluorescence emission wavelength of the probe enters into the near-infrared fluorescence region.Moreover,the probe uses 1-methylpyrrolidium as the specific recognition group for cyanide.After interacting with cyanide,the probe can generate a ratiometric near-infrared fluorescence response by regulating the intramolecular charge transfer efficiency of the probe.The spectroscopic experiment shows that the detection limit and quantitative limit are 0.075μM and 0.25μM respectively.Moreover,the ratio of fluorescence intensity(I₅₁₉/I₆₈₈)of the probe to cyanide is linear with the concentration of cyanide in the range of 0 to 80μM.Significantly,the practical application experiment shows that the probe can be successfully used to accurately and quantitatively detect cyanide in various food samples,such as almond,sprouting potatoes and bamboo shoot.2.A dual-functional fluorescent probe for simultaneously discriminating ClO^-and ¹O₂ in living organism.We firstly noted that 3-（aliphaticthio）-propan-1-one group displayed different recognition reaction with ClO^-and ¹O₂.Based on the recognition group,we proposed the first fluorescent probe to simultaneously discriminate ClO^-and ¹O₂ with high sensitivity and selectivity.The probe itself showed fluorescence in blue channel.After treatment with ClO^-and ¹O₂respectively,pronounced fluorescence enhancements were observed in the green channel and red channel correspondingly.Moreover,upon development of the probe with aggregation-induced emission（AIE）characteristics,the probe could work well in a solution with high water volume fraction.The probe was also able to accumulate into mitochondria and was utilized as an effective tool to image exogenous and endogenous ClO^-and ¹O₂ in mitochondria.Significantly,as the first trial,the probe was employed to simultaneously monitor the variation of ClO^-and ¹O₂ level in cecum tissues of rat in the cecal ligation and puncture（CLP）-induced polymicrobial sepsis model.The results demonstrated that the expressed ClO^-and ¹O₂ levels were tightly correlated with the severity of sepsis,inferring the overproduction of ClO^-and ¹O₂ is an important factor for the pathogenesis of sepsis.The probe illustrated herein may provide a guide for further exploring the functions of ClO^-and ¹O₂ in various diseases.