Application Of Doped Quantum Dots ZnS:Mn²⁺ In Pharmaceutical And Metal Ions Analysis

In recent years, as a new type of fluorescence material, quantum dots (QDs) offered a number of attractive optics features. And it was used to detected different matters, due to the different function of ligand molecules. The combination of QDs with drug, not only improved the biocompatible of QDs, but also could be used to detect drug molecules and montior the metabolism process of drug. The thesis described the modification of quantum dots with drugs molecular, and the quantitative detection of drug molecules using functionalized quantum dots. This thesis was divided into five chapters to present.In Chapter 1, The concept, the nature and preparation methods development of quantum dots were briefly described. The species and special functionalizing of ligand molecules were introduced. The application and research about quantum dots in pharmaceutical analysis were briefly summarized.In Chapter 2, Aqueous thioglycolic acid capped ZnS:Mn2+ quantum dots (ZnS:Mn2+ QDs) with a orange emission were prepared under the room temperature. Based on the fluorescence quenching of ZnS:Mn2+ QDs caused by Sulfadiazine Sodium (SDS), a simple, rapid and specific quantitative method was proposed to the SDS determination. Factors affecting the fluorescence detection for SDS with ZnS:Mn2+ QDs were studied. Under the optimal conditions, the calibration plot of I0/I with concentration of SDS was linear in the range of 1.25×10-5 -3.75×10-4 mol·L-1 with correlation coefficient of 0.998. The limit of detection LOD (3σ/k) was 3.86×10-6mol·L-1. The possible interaction mechanism was discussed.In Chapter 3, Water-soluble L-cysteine-modified-ZnS:Mn2+ Quantum dots were prepared in aqueous solution under the room temperature, and characterized by Infrared spectrometry, ultraviolet-visible spectrometry, spectrofluorometry and X-ray diffraction spectrometry. Based on the fluorescence quenching of ZnS:Mn2+ QDs caused by Folic Acid (FA), the prepared Quantum dots were evaluated as fluorescence probe for FA detection. Factors affecting the fluorescence detection for FA with ZnS:Mn2+ QDs were studied. Under optimal conditions, the quenched fluorescence intensity was linear with the concentration of FA ranging from 1.00×10-6-7.00×10-5 moL·L-1 with correlation coefficient of 0.994. The limit of detection for FA was 9.62×10-7moL·L-1.In Chapter 4, Mn doped ZnS Quantum dots (ZnS:Mn2+ QDs) were prepared through a co-precipitation method of using N-Acetyl-L-Cysteine (NAC) as ligand molecules. The properties of QDs were also characterized by Infrared spectrometry, ultraviolet-visible spectrometry, spectrofluorometry and X-ray diffraction spectrometry. The fluorescence of ZnS:Mn2+ QDs was quenched after adding Tetracycline hydrochloride (TC). Factors affecting the fluorescence detection for TC with ZnS:Mn2+/NAC QDs were studied. Under optimal conditions, the quenched fluorescence intensity increased linearly with the concentration of TC ranging from 0.832-7.94×10-5mol·L-1 with correlation coefficient of 0.997. The limit of detection for TC was 6.91×10-7mol·L-1.In Chapter 5, Mn2+-doped zinc sulfide quantum dots modified with tiopronin (TP) (QDs-TP) were prepared through a co-precipitation method of using an aqueous solution. The properties of QDs-TP were characterized by infrared, X-Ray, fluorescence, and UV-vis absorption spectroscopies. In KH2PO4-NaOH buffer solution of pH 7.20, the presence of Hg2+ led the fluorescence intensity of QDs-TP to decrease significantly. The intensity change was proportional to the concentration of Hg2+ in the range of 2.00×10-8-1.80×10-7 mol·L-1 and the detection limit of Hg2+ was 8.88×10-9 mol·L-1. The introduced method was successfully applied to the determination of traces of Hg2+ in synthetic sample with recovery from 99% to 116%.