Construction Of Novel Chemiluminescence Method Based On Silicon Quantum Dots And Its Application

Chemiluminescence（CL）is a type of light radiation produced by chemical reaction without an external source of excitation light.Chemiluminescence analysis method is based on chemiluminescence reaction,and it has the advantages of simple instrumentation,low background signal,high sensitivity,rapid analysis speed,wide linear detection range and so on.It has been used extensively in environmental monitoring,dietary analysis,clinical diagnosis and other fields.However,the traditional chemiluminescence system has some shortcomings,such as low chemiluminescence efficiency,weak inherent signal,unstable reaction reagent and insufficient reaction specificity,it can not meet the requirements of analytes detection well.Therefore,the improvement of traditional chemiluminescence system and the construction of new chemiluminescence methods have become the focus of researchers,including the search for new catalysts,new oxidants,new luminant material and combined with other technologies.Quantum dots（QDs）are widely used in the CL system because of their excellent optical properties such as tunable emission spectrum,high light efficiency and long fluorescence lifetime.Unlike traditional luminescent reagents,the emission wavelength of quantum dots can be adjusted from near ultraviolet to near infrared,greatly expanding their applications in biomedicine.In the CL system,quantum dots can play the role of luminant material,catalyst,energy acceptor and so on,which can significantly improve the strength of CL to meet the demand of detection.In comparison to the case of metallic quantum dots,non-metallic quantum dots have some outstanding advantages,such as low preparation cost,low toxicity,and good biocompatibility.Silicon quantum dots（Si QDs）,a kind of non-metallic quantum dots,are cheap,almost non-toxic zero dimensional materials.Silicon elements naturally exist in living organisms,which provides the basis for excellent compatibility of silicon quantum dots.At present,silicon quantum dots are rarely used in chemiluminescence,so in this paper,they are introduced into CL system to build a new chemiluminescence analysis method,and broaden the new thinking of chemiluminescence research.Based on the reported literature,water-soluble silicon quantum dots（Si QDs）and fluorine-doped silicon quantum dots（F-Si QDs）have been synthesized,and a series of characterization and properties of the materials have been studied.The novel chemiluminescence method was constructed by using materials in different systems,as well as its mechanism and application,were investigated.The full text consists of 5 chapters:The first chapter is a summary,which briefly introduces the concept,mechanism and research progress of chemiluminescence,the application of quantum dots in chemiluminescence,and the significance and content of this paper;Chapter 2-4 are the specific research content;Chapter 5 summarizes the full text.The main research contents are as follows:1.Potassium Ferricyanide Oxidize Silicon Quantum Dots to Produce Chemiluminescence for Uric Acid Detection in Human UrineThe water-soluble Si QDs were synthesized by reference to the method of literature.After analyzing the redox characteristics,the CL phenomenon of Si QDs-K₃[Fe（CN）₆]-Na OH system was studied in this experiment,Si QDs were first used as luminescent in chemiluminescence systems.Under alkaline condition,it could be oxidized by K₃[Fe（CN）₆]to produce CL emission.Uric acid（UA）could inhibit the CL signal of Si QDs-K₃[Fe（CN）₆]-Na OH system.Based on this,a new UA detection method was built.In the optimum experimental condition,a linear detection range of 0.50 to 4.50 mmol·L^-1was used,and a limit of detection of 0.24 mmol·L^-1（S/N=3）.In conclusion,the method was successfully applied to UA detection in human urine.2.Chemiluminescence of Luminol Catalyzed by Fluorine-doped Silicon Quantum Dots and Its ApplicationF-Si QDs were synthesized by hydrothermal method and first used in chemiluminescence system.It was found that F-Si QDs can significantly enhance the CL signal of luminol-H₂O₂ system,and the enhancement mechanism was studied.The addition of histidine（His）caused a decrease in the CL intensity of the F-Si QDs-luminol-H₂O₂ system.On this basis,a new method for His detection was proposed.The method showed a good linear relationship between His concentration and CL intensity in the range of 1-7μmol·L^-1,and the detection limit was 0.91μmol·L^-1（S/N=3）.The influence of other common substances in human serum on this method could be ignored.This method has been successfully applied to detect His in human serum specimens.3.Fluorine-doped Silicon Quantum Dots Promote Chemiluminescence of Calcein and Its MechanismAs a fluorescent material,calcein was able to react with H₂O₂ to produce a weak CL signal in alkaline media.The addition of F-Si QDs synthesized by hydrothermal method could significantly improve the CL intensity of calcein-H₂O₂ system,and this phenomenon was studied and discussed.Through the analysis of CL kinetics,UV-vis absorption spectrum and fluorescence spectrum of the system,combined with the study of free radical scavenging experiment and chemiluminescence spectrum,the potential mechanism may be that F-Si QDs with good peroxidase activity catalyzed H₂O₂ and dissolved oxygen to generate active free radicals under alkaline conditions.Further oxidation of calcein and F-Si QDs produced strong emission of CL.Because of the good biocompatibility of F-Si QDs,this method has the possibility to be applied to practical detection.