The Synthesis And Application Of Functional ZnS Nanoparticles For Fluorescence Analysis

Semiconductor nanoparticles have excellent spectral characteristics and photochemical stability with broad application prospects because of its unique optical properties in quantitative analysis and biological imaging.Functionalized ZnS nanoparticles as fluorescence probes were widely used in the determination of nucleic acid,protein,peptide,Cu²⁺.However,the use of functionalized ZnS nanoparticles as fluorescence probe in the determination of norfloxacin and propylthiouracil has not been reported.L-cysteine-capped ZnS nanoparticles are prepared as fluorescence probe in the determination of propylthiouracil and norfloxacin in this paper.This method is simple,rapid,accurate,and may be used directly for the determination of norflxacin and propylthiouracil with satisfactory results.Fluorescence capillary analysis method uses a capillary as a carrier for fluorescence reaction and determination,and with this method analysis of micro samples has been realized.Its advantages are simple to manipulation,thimbleful of sample and reagent volumes. The aforementioned fluorimetric methods could be ported to micro fluidic chip analysis system.The paper consists of five chapters.In chapter 1,the characteristics of nano-materials are briefly introduced,luminescent mechanism and luminescence properties as well as its surface modification are described,recent developments with preparation and applications of ZnS semiconductor nanoparticle as well as doped ZnS semiconductor nanoparticle materials are reviewed.In chapter 2,a sensitive fluorimetric method for determining norflxacin in pharmaceutical samples with L-cysteine-capped ZnS nanoparticles as fluorescence probe is established.The effect of L-cysteine-capped ZnS nanoparticles on the fluorescence intensity of norflxacin has been investigated.It is found that the fluorescence intensity of the system is greatly enhanced duo to the interactions of norflxacin and L-cysteine-capped ZnS nanoparticles in the KH₂PO₄-NaOH buffer solution.The optimal pH is 6.5 and the optimal concentration of L-cysteine-capped ZnS nanoparticles is 4.0×10^-4 mol·L^-1.Under optimum conditions,the fluorescence intensity of the system shows a good linear relationship with the concentration of norflxacin in the range of 4.0×10^-9 to 1.2×10^-6 mol·L^-1,the correlation coefficient is 0.9985,the detection limit(S/N = 3) is 7.4×10^-10 mol·L^-1 and the limit of quantification(S/N= 10) is 4.0×10^-9 mol·L^-1.The RSD is 1.8%for the determination of 1.6×10^-7 mol·L^-1 norflxacin(n = 9).In chapter 3,the effect of propylthiouracil on the fluorescence intensity of L-cysteine-capped ZnS nanoparticles has been investigated.It is found that the fluorescence intensity of the functionalized ZnS nanoparticles could be quenched by propylthiouracil in the KH₂PO₄-NaOH buffer solution at pH = 6.5.Accordingly,a sensitive fluorimetric method for determining propylthiouracil in pharmaceutical samples with functionalized ZnS nanoparticles as fluorescence probe is established. Under optimum conditions,the fluorescence intensity of the system shows a good linear relationship with the concentration of propylthiouracil in the range of 4.0×10^-6 to 4.0×10^-4 mol·L^-1,the correlation coefficient is 0.9987 and the detection limit(S/N=3) is 1.7×10^-6 mol·L^-1.The relative standard deviation of replicate eleven measurements is 1.49%for 4.0×10^-5 mol·L^-1 propylthiouracil.In chapter 4,preliminary inquiry on fluorescence capillary analysis is conducted. The norfloxacin and isothiocyanate are directly determinated in the capillary.Then fluorescence capillary analysis method is used in the determination of trace Ce⁴⁺.In chapter 5,the synthesis and application of functional ZnS nanoparticles in fluorescence analysis are summarized,and the development of fluorescence capillary analysis system,as well as the application of functionalized inorganic nanoparticles in capillary and micro-fluidic chip system is prospected.