Preparation And Grafting Of CdTe, CdHgTe Nanoparticles And Their Application On The Determination Of Proteins

In recent years,semiconductor quantum dots(QDs) have attracted great interests in synthesis and application due to their extensive physical and chemical effects.In this thesis,a novel method for the determination of proteins with CdHgTe QDs as a near-infrared fluorescence probe was developed;Based on the synthesis,the influence of the graft reagents which have an amino or a carboxyl terminus with different chain lengthes on the fluorescence properties of water-soluble thioglycolic acid stabilized CdTe nanocrystals(TGA-CdTe) were investigated;Sphere and rod CdTe NCs were prepared in aqueous solution using thioglycolic acid(TGA), L-cysteine(L-cys) and both of them as stabilizers;Furthermore,combining MIP and the QDs could improve the selective detection of the protein.Major works of this thesis can be outlined as follows:(1) The fundamental theory of QDs,general strategies of QDs preparation, character method and their extensive application on bioscience are reviewed.(2) CdHgTe nanoparticles(NPs) with the emission in the near-infrared region were prepared in aqueous solution,and were characterized by transmission electron microscopy,X-ray diffraction spectrometry,spectrofluorometry and ultraviolet-visible spectrophotometry.The synthesized CdHgTe NPs show much promise because their NIR wavelength can be tuned by the composition and the incubation temperature.CdHgTe NPs combined the virtue of the stable and high fluorescence intensity of CdTe NPs and the NIR wavelength tuning of HgTe NPs.On one hand,the tuning of the emission wavelength of CdHgTe NPs is easier than that of single material NPs(CdTe or HgTe) by controlling the synthetic conditions.On the other hand,CdHgTe NPs are stable than HgTe NPs. Based on the fluorescence quenching of CdHgTe NPs in the presence of proteins, a novel method for the determination of proteins with CdHgTe NPs as a near-infrared fluorescence probe was developed.Under the optimal conditions, the calibration graphs were linear in the range of 0.04×10^-6-5.6×10^-6 g·mL^-1 for lysozyme(Lyz) and 0.06×10^-6-6.1×10^-6 g·mL^-1 for bovine hemoglobin(BHb), respectively.The limits of detection were 13 ng·mL^-1 for Lyz and 27 ng·mL^-1 for BHb,respectively.Four synthetic samples were determined and the results were satisfied.(3) The influences of the graft reagents which have an amino or a carboxyl terminus with different chain lengthes on the fluorescence properties of water-soluble thioglycolic acid stabilized CdTe nanocrystals(TGA-CdTe) were systematically investigated.Strong enhancement effects of the grafting on the fluorescence intensity of TGA-CdTe were observed.The experiment results demonstrated the short chain length grafting can increase the fluorescence intensity of the CdTe nanocrystals(NCs) better than that of long chain length grafting,and the grafting did not influence the emission wavelength of the CdTe NCs.The fluorescence intensity of the carboxyl grafted TGA-CdTe was more stable than that of the amino grafted TGA-CdTe at wide pH ranges(pH 5.1-10.0).(4) Sphere and rod CdTe NCs were prepared in aqueous solution using thioglycolic acid(TGA),L-cysteine(L-cys) and mixture of them as stabilizers.By only changing the molar ratio of the two stabilizers,highly luminescent CdTe NCs can be selectively prepared.With the increasing amount of the molar fraction of L-cys in the mixed stabilizers of TGA and L-cys,the aspect ratio of the NCs was increased and the emission wavelength was shifted to long wavelength range. When the molar fraction of the L-cys in the mixed stabilizers was 25%,the fluorescence intensity of the NCs was the highest.(5) By combining the virtue of the sensitivity of CdTe and the selectivity of the MIP,a selective and sensitive fluorescence method for the determination of Lyz was developed.Since NIPA polymer undergoes a reversible swelling-shrinking cycle in response to the external environment,the rebinding ability and elute are controllable by changing the solution environment,which was convenient for the next determination step.Different influencing factors were studied,including the pH value,concentration of NaCl and temperature.The experiment results demonstrated that the optimized adsorption conditions were as follows:room temperature,Tris-HCl buffer solution with pH 8.10,20 mM NaCl.The optimal elution condition was citric acid-triple sodium citric acid buffer with pH 6.10. The Lyz in three synthetic samples were determined with CdTe as the fluorescence probe after the synthetic samples were pretreated by MIP-PNIPA, and the recoveries were 90.2～102%.This method provided a new way to study the determination of proteins.