Synthesis Of New Functionalized Quantum Dots And Their Application In Analytical Chemistry

Nowadays, the research and technical exploiture of quantum dots (QDs) is one of the most interesting fields in science. At present, the focus researches are the preparation and application of quantum dots with good stability, excellent biocompatibility and powerful multifunction. In this dissertation, the authors mainly studied on the synthesis and application of new functionalized quantum dots. The dissertation includes four chapters, the main contents and results are summarized as follows:Chapter one, the basic conception and physical property of quantum dots were introduced. The authors reviewed the recent progress about the synthesis, surface modification and application in bioanalytical chemistry, and analyzed the limitation on the synthesis and application of quantum dots, and then put forward the research goal of this dissertation.Chapter two, the authors firstly proposed an ultrasonic assistant method to prepare NaHTe, and reported a water-thermal synthesis protocol for producing novel, multifunctional, highly water-soluble Mn-doped CdTe/ZnS core-shell quantum dots with both fluorescence and phosphorescence via an alternative complexing-doped method using 3-mercaptopropionic acid (MPA) as a stabilizer. Influence factors, including the pH value, reaction temperature, reflux time and atmosphere were investigated. The characterizations of Mn-doped CdTe/ZnS quantum dots were also identified using AFM, IR, powder XRD and thermogravimetric analysis. A new approach was developed for the sensitive and selective detection of trace mercury ions with Mn-doped CdTe/ZnS quantum dots as phosphorescence probes. Influence factors, including the concentration and pH of buffer, reaction time and quantum dots concentration, were investigated. Under the optimum conditions, a good linearity was obtained between lg(P0/P) and the concentration of mercury ions ([Q]) in the range from 5.0×10^-8 to 1.0×10^-5 mol/L with the correlative coefficient of 0.9979 and a detection limit of 4.3×10^-9mol/L. The interaction mechanism between mercury ions and quantum dots has been primarily discussed. The proposed method has been successfully applied to detect the content of mercury ions in water samples, and the recoveries were found to be 98.24¹07.2% with standard addition method.Chapter three, the authors have synthesized silica capped Mn-doped ZnS quantum dots (ZnS:Mn@SiO₂) in water phase. Phosphorescent compositenanoparticle, molecularly imprinted polymers (MIP) appended onto silica capped Mn-doped ZnS quantum dots (ZnS:Mn@SiO₂@MIP), were prepared using bovine serum albumin (BSA) as template molecular and 3-Aminophenylboronic acid (APBA) as functional monomers. Quantum dots functioned by molecular imprinting technique, incorporation of semiconductor nanoparticles into molecularly imprinted polymer, provide a sensor material which can be easily shaped and with better selectivity and high sensitivity because the photoluminescence emission of quantum dots significantly. The molecularly imprinted polymer capped Mn-doped ZnS composite materials were characterized using AFM, IR, powder XRD and thermogravimetric analysis. Both traditional and phosphorescent measurements were applied to study the optical and selective properties. The results showed that the as-prepared ZnS:Mn@SiO₂@MIP possessed very excellent opticalchemistry property and good selectivity to template molecular BSA.Chapter four, Mn-doped ZnS quantum dots were functionalized by molecularly imprinted polymers to make ZnS:Mn@MIP of 2,4-difluorophenol constructed by sol-gel method. The selectivity and recognisition of ZnS:Mn@MIP was studied by phosphorescence spectra. The results suggested that the as-prepared ZnS:Mn@MIP revealed very excellent recognisition and good selectivity to 2,4-difluorophenol.