Preparation Of Quantum Dots And Its Application In PBC Diagnosis

Primary biliary cholangitis(primary biliary cholangitis,PBC)is an autoimmune disease that has no obvious symptoms in the early stages and is difficult to find.When the patient was diagnosed with PBC,the condition had already progressed to cirrhosis or liver failure,and it was difficult to cure.Therefore,we need a disease early diagnosis method for the prevention of early asymptomatic diseases such as PBC.Fluorescence immunochromatography is an important in-vitro diagnostic method for diseases.It is simple and fast,and it can be self-checked at home without professionals,which has great potential for early diagnosis of diseases.At present,the most widely used fluorescent immunochromatography is colloidal gold immunochromatography,but the sensitivity of colloidal gold cannot meet the needs of quantitative detection of fluorescent immunochromatography and simultaneous detection of multiple substances,which limits the further application of fluorescent immunochromatography.Quantum dots,a new type of fluorescent semiconductor nanomaterials,have better fluorescent properties than organic fluorescent dyes and colloidal gold.Quantum dots have good photobleaching resistance,wide excitation spectrum and narrow emission spectrum.As a fluorescent marker,its sensitivity is higher than that of colloidal gold,so it has become a popular choice for fluorescent markers in fluorescent immunochromatography.Staphylococcal protein A(SPA)can combine to antibody biomolecules in human serum without affecting the binding activity of the antibody to antigen,and at the same time it can also be combined to fluorescent markers.This unique biological activity of SPA provides an idea for the simultaneous detection of multiple substances by fluorescence immunochromatography.Based on this,quantum dot-SPA conjugates with excellent fluorescence properties were prepared for fluorescent immunochromatography to simultaneously detect multiple substances,which provided a basis for the further application of fluorescent immunochromatography in the early diagnosis of diseases.Chapter 1 ReviewThis chapter first introduces the incidence and diagnosis of primary biliary cholangitis in different regions.Then,the classification of QDs,preparation method of QDs,surface modification method of QDs and coupling method of protein biomacromolecule with QDs are introduced.Finally,the principle of fluorescence immunochromatography,the advantages of quantum dot fluorescence immunochromatography and the development direction of fluorescence immunochromatography are introduced.Chapter 2 Preparation and Characterization of CdTe Quantum DotsIn this chapter,cadmium telluride quantum dots with good fluorescence properties are prepared and characterized by various methods.First,the aqueous phase preparation method was used to prepare mercaptopropionic acid as a modifier to prepare carboxylmodified water-soluble cadmium telluride quantum dots.The reaction time of quantum dot preparation was investigated,and various methods such as particle size,ultraviolet absorption and fluorescence emission spectroscopy were used for characterization.The results show that with the extension of the reaction time,the maximum emission wavelength of cadmium telluride quantum dots shows a red-shifted trend,and the fluorescence intensity tends to increase first and then decrease.The optimal reaction time is 3 h,the particle size is 9 nm,the potential is-20 mV,the fluorescence quantum yield is 33%,and the stability is poor in an acid environment.Chapter 3 Optimization of coupling conditions of CdTe quantum dots and staphylococcal protein AIn this chapter,CdTe quantum dots with excellent fluorescence properties prepared in Chapter 2 are used to couple with staphylococcal protein A.The influence of the amount of EDC,NHS,SPA and the reaction time on the coupling effect was investigated using a single factor inspection method.The optimal reaction conditions were screened out to prepare the CdTe quantum dot-SPA conjugates with better fluorescence performance.The particle size,potential,ultraviolet absorption spectrum,fluorescence emission spectrum and biological activity of the conjugates were characterized.The results showed that the particle size of the conjugates was 55 nm and the potential was-26.9 mV.The ultraviolet absorption and fluorescence emission spectra were red-shifted,indicating that the particle size of the conjugates increased,which indirectly proved that the conjugates was successfully prepared.Subsequently,spot verification was used to prove that the conjugates was still biologically active and could combine to SPA antibodies.Chapter 4 Preparation of quantum dots fluorescence immunochromatography test stripThe purpose of this chapter is to use the CdTe quantum dots-SPA conjugates prepared in Chapter 3 for fluorescent immunochromatography to detect PBC characteristic antibodies(AMA-M2 antibody and gp210 antibody).It provides the basis for fluorescent immunochromatography based on SPA to detect multiple substances simultaneously.