Synthesis Of Magnetic Nanoparticles In Reverse Microemulsion And The Study On The Conjugation Mechanism Between CdTe Quantum Dots And Metal Ions By Capillary Zone Electrophoresis

In recent years, the preparation, characterization and biomedical applications of magnetic, fluorescent and magnetic fluorescent hybrid nanoparticles have attracted much attention. Therefore, it is very important to establish and improve the methods to prepare well-dispersed and stable nanomaterials with uniform size and morphology.Quantum nanoparticles dots (QDs) or semiconductor nanocrystals are a specific kind of nanoparticles newly developed in recent years because of their unique optical properties such as broader excitation spectrum, narrower emission spectrum and longer lifetime. CdTe QDs has often been investigated due to its unique size-dependent fluorescence tunable across the visible spectrum. It is possible to synthesize differently sized CdTe nanocrystals that emit from blue to red with very pure color. CdTe QDs have exhibited great potential as a new type of labeling and detection probe for heavy metal ions, organic small molecules and protein, et al. However, the study on their conjugation mechanism still stays at a mixture level which does not have a separation process. So, it will be of great significance to establish new separation systerm.Based on the above reasons, this dissertation is divided into four chapters:Chapter 1:This chapter reviewes the main property and characterization methods of magnetic and quantum nanomaterials, and also reviewes the advantages of quantum dots as fluorescent labeling and the application of capillary electrophoresis in the quantum dots study.Chapter 2:In this chapter, we present here a facile method of synthesis based on the reverse microemulsion route at room temperature, and the obtained polyhedral nanocrystals exhibited superparamagnetic property.Chapter 3:In this chapter, water soluble CdTe QDs capped with thioglycollic acid (TGA) is synthesized, the fluorescence of CdTe QDs can be strongly quenched by low concentration of Hg2+, so CdTe QDs are a sensitive probe to Hg2+. UV/fluorescence spectroscopy is applied to the conjugation mechanism study between CdTe QDs and Hg2+. Capillary zone electrophoresis (CZE) coupled with laser-induced fluorescent (LIF) detection and UV absorption detection has been introduced to study the detailed conjugation mechanism for the first time. The preliminary results show that the competitive ligands (capping molecule) binding between the QDs core and the metal ions present in the solution was the nature quenching mechanism for the remarkable quenching effect of Hg2+.Chapter 4:In this chapter, the conjugation mechanism between CdTe QDs and Cu2+, Pb2+ in aqueous solutions are deduced by UV/fluorescence spectroscopy and capillary zone electrophoresis (CZE). The fluorescence quenching mechanism of Pb2+ on CdTe QDs was similar to that of Hg2+. However, the conjugation mechanism of Cu2+ with CdTe QDs was different, which can be seriously affected by the presence or absence of the free ligands in the aqueous solution. As the free ligands have profound effects on fluorescence response of QDs to Cu2+. As the free ligands were present, the quenching mechanism may be that CdTe QDs might give up the electron to Cu2+, thereby by reducing them to Cu+ ions, and the formation of CU2S on the surface of the QDs.While as the free ligands were removed, the competitive ligands (capping molecule) binding between the QDs core and the metal ions present in the solution was the quenching mechanism.