| Quantum dots(QDs), a new kind of nanomaterials, have their unique properties, such as narrow emission spectra and broad excitation spectra. Recently, quantitative analysis based on quantum dots fluorescent sensors showed relatively low selectivity over competing metal ions, which limits the application of quantum dots. As the detection performance of quantum dots is closely relative to their surface state, to improve the selectivity, the surface of quantum dots was often funtionalized with some materials, which can highly identify target molecules.Mercury ion(II), a dangerous pollutant in water, can cuase lethal effects on human health even at very low concentrations. However, the reported ?uorescent sensor for Hg2+ often couldn’t eliminate the interference of Cu2+ and Ag+. Rutin, a type of the most abundant bioactive flavonoid, is widely applied in medicine. So it is necessary to establish simple and sensitive methods for determining rutin in biological samples. This work is focused on the high selective detection of Hg2+ and sensitive detection of rutin. The thesis was divided into the following several parts:(1) A fluorescent sensor for mercury ion(II) based on cetyltrimethylammonium bromide functionalized Zn Se quantum dots. With the Zn(Ac)2 as Zn sourse, Na HSe as Se sourse and glutathione as the stabilizer, water-soluble Zn Se QDs were synthesized by reflux method. Cetyltrimethylammonium bromide functionalized Zn Se QDs(CTAB/Zn Se QDs) were synthesized through electrostatic self-assembly. Compared to Zn Se QDs, CTAB/Zn Se QDs showed higher fluorescence quantum yield and higher recognition selectivity to Hg2+. Under the optimum conditions, the fluorescence quenching effect and the concentration of Hg2+ in the range from 0.010 μmol/L to 2.0 μmol/L showed a good linear relationship with a detection limit of 0.0040 μmol/L. This fluorescence sensor was successfully applied in the detection of Hg2+ in lake water and recoveries were ranged from 97.5%-105%(2) A fluorescent sensor for mercury ion(II) based on poly(diallyl dimethyl ammonium)chloride functionalized Cd Te quantum dots. With the Cd Cl2 as Cd sourse, Na HTe as Te sourse and thioglycolic acid as the stabilizer, water-soluble Cd Te QDs in aqueous media were synthesized by reflux method. PDDA functionalized Cd Te quantum dots(PDDA/Cd Te QDs) were synthesized, and the results from spectra, zeta potential and AFM demonstrated that interaction between PDDA and Cd Te QDs was electrostatic interaction. As PDDA could stop Cu2+ and Ag+ quench the fluorescence of Cd Te QDs, PDDA/Cd Te QDs could effectively eliminate the interference of Cu2+ and Ag+. Under the optimum conditions, the ?uorescence quenching effect of PDDA/Cd Te QDs was linear with the concentration of Hg2+ in the range from 0.0060 μmol/L to 1.0 μmol/L, and the detection limit was 5.0 nmol/L.(3) A ?uorescent sensor for mercury(II) ion detection based on cysteamine capped Cd Te quantum dots. Cysteamine(CA) capped Cd Te quantum dots(CA-Cd Te QDs) were prepared by reflux method. Based on the strong affinity of mercury to nitrogen atom, the influence of the 10 fold Cu2+, Ag+ on the determination of Hg2+ was less than 7%. Under the optimum conditions, the fluorescence quenching effect of CA-Cd Te QDs was linear with the concentration of Hg2+ at the range from 6.0 nmol/L to 450 nmol/L, and the detection limit was 4.0 nmol/L. This sensor was successfully applied in the detection of Hg2+ in lake water and the recoveries were ranged from 95.0% to 106%.(4) A ?uorescent sensor for rutin detection based on cysteamine capped Cd Te quantum dots. In a weak alkaline solution, a novel fluorescence sensor for rutin was peoposed based on the charge-charge interactions and the hydrogen bonding interactions and common metrials in serum samples showed no interference to the detection of rutin. Under the optimum conditions, the proposed sensor could efficiently be used for rutin sensing at very low concentration with a detection limit of 0.0020 μmol/L with the linear working concentration range of 0.0060 μmol/L-1.0 μmol/L. Based on the data of ultraviolet spectrum and fluorescence spectrum, it was surmised that rutin quenched the fluorescence of CA-Cd Te QDs by electron transfer caused by charge-charge interactions and the hydrogen bonding interactions. |
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