| Preparation, chemical functionalization of core/shell QDs and functionalized polystyrene microsphere and their applications as fluorescent labeling are one of the most important subjects in the fields of biochemistry, molecular biology, cell biology, proteomics, medicine, and so on. The technologies of preparing core/shell QDs and functionalized polystyrene microsphere, and their applications are reviewed in this dissertation. The dissertation is divided into two parts. In the first part, the preparation, characterization and applications in chemical and biological analysis of core/shell quantum dots as the line of this part, we devote to developing a multiplex fluorescence detection method with higher sensitivity, simpler operation, and lower cost. The second part focuses on the preparation of functionalized polystyrene microsphere, and conjugated with QDs or FITC to get polystyrene fluorescent composite microsphere. The main detail is as follows:MPA-CdSe/ZnS core/shell quantum dots were synthesized and a rapid method was established to detect the bacterial count by using CdSe/ZnS core/shell quantum dots as a fluorescence marker, Escherichia coli acted as detection target bacteria and EDC/NHS as the crosslinker based on different bacterial count get rise to different fluorescence intensity of the system. Under the optimized conditions, the fluorescence peak intensity was proportional to the bacterial count in the range of 102-108 CFU/mL and the low detection limit was 102 CFU/mL. The results of determination for the total count of bacteria in five real samples were identical with the conventional plate count method, and the relative standard deviation (R.S.D%.= 5.9-8.8) were satisfactory. The concept demonstrated that the application of core/shell CdSe/ZnS nanocrystals as fluorescent probes to detecting the total bacterial count was feasible.Based on the reverse microemulsion technique, silica-coated CdSe/ZnS core/shell quantum dots were prepared at moderate conditions by employing CdSe/ZnS as the core and silica as the shell of the nanoparticles, and a new, rapid method was established to detect the bacterial count. This method was useful and simple for obtaining silica coated nanoparticles with low toxicity, high photostability, and sizes and distributions of the nanoparticles were uniform. Moreover, silica-coated CdSe/ZnS core/shell quantum dots were modified with amine groups and phosphonate groups, and could successfully covalently conjugated with the bacteria using glutaraldehyde as the crosslinker. Under the optimized conditions, the fluorescence peak intensity was linear with the bacterial count in the range of 3×102-107CFU/mL and the low detection limit was 3×102 CFU/mL. The results of determination for the total count of bacteria in seven real samples were identical with the conventional plate count method, and the standard deviation was satisfactory.The citrate-stabilized CdSe/CdS quantum dots were synthesized by using CdCl2·2.5 H2O, Se powder and Na2S as precursors instead of any pyrophoric organometallic precursors and a rapid, ultrasensitive, convenient fluorescence measurement technology was developed for quantitative detection of protein based on water-soluble CdSe/CdS core/shell quantum dots. These hydrophobic CdSe/CdS quantum dots were uniformity. No obvious change of fluorescence intensity of quantum dots was observed after it was excited for 3600 seconds by successive intense irradiation, which demonstrates that these quantum dots had excellent photostability. The fluorescence signal of CdSe/CdS was enhanced by increasing the concentration of BSA in the range of 0.1-10μg/mL, and the low detection limit is 0.06μg/mL. This method was superior to the recently reported methods for detecting BSA that use classical dyes. The results of determination for bovine serum albumin in three synthetic samples were identical with the true value, the recovery and relative standard deviation were satisfactory. This approach offered the possibility in quantitative detection of other kinds of proteins.By using the above-prepared CdSe/ZnS core/shell quantum dots, a novel method was established to detect ethanol based on the quenching of CdSe/ZnS core/shell QDs photoluminescence (PL) emission by H2O2 produced by alcohol oxidase (AOD) catalyzed alcohol oxidation. The effect of parameters such as pH, reaction time, reaction temperature and concentration of AOD were discussed. The fluorescence signal of CdSe/ZnS core/shell QDs was decreased by increasing the concentration of ethanol in the range of 0.1 mM-8 mM, and the low detection limit was 0.05 mM. The results of determination for real samples were identical with the true values, the relative error (2.9-4.9%) was small.Thiol-functionalized polystyrene microspheres were synthesized by using 4-VBTU, styrene and DVB as monomer, and a straightforward, reproducible method of irreversibly immobilising the high level of the QDs (6-15% weight of the conjugate materials) QDs into thiolated polymeric particles was established. The first demonstration of the use of functionalised polystyrene beads as "polymeric ligands" for the immobilisation of quantum dots (QDs) was presented. The composite materials had high stability in polar or nonpolar solvent and retained the similar emission spectrometry with CdSe/ZnS QDs.Silica-shelled polystyrene microspheres were prepared and coupled with FITC to get a new fluorescence composite material. The microspheres were characterized by laser diffractometer, fluorescence spectroscopy and SEM. The thickness of silica shells, fluorescence of the composite particles and amine loading could be adjusted in a highly controlled manner. In addition, the composite material could be covalently coupled with GFP by EDAC as the crosslinker. It made them become ideal candidates for use in bioimaging applications.
|
PDF Full Text Request