Synthesis And Modification Of Cdse Quantum Dots And Preparation Of Fluorescent Magnetic Nanoparticles

Quantum dots (QDs),also called semiconductor nanocrystals, have great potential applications in biomedical research, because of their unique optical and electrical properties. In this paper, firstly, high quality hydrophobic CdSe QDs were prepared and modified with alloyed shell structure; Then, QDs were modified to be water-soluble by multidentate polymer poly(glutamic acid)-graft-cysteamine (PGA-g-MEA) which was successfully synthesized by employing amino acids as molecular main chain, and the properties of water-soluble QDs were further investigated; Thirdly, the fluorescent magnetic nanoparticles (FMNPs, QDs-Fe3O4) were preliminarily prepared by ring opening reaction. The details were shown as follows,1. Monodispersed and highly crystallized CdSe QDs were successfully prepared by colloid chemistry method with the emission wavelength between 524.9nm and 596.8nm, the full width at half maximum (FWHM) peak about 30nm and a highest quantum yield (QY) of about 27.2%. And then, the influences on optical properties of QDs from the ratio of precursors and reactive time were investigated. The results showed by ultraviolet visible spectra (UV-Vis) and photoluminescence (PL) indicated that along with the increased ratio of precursors and reactive time, the size of QDs got bigger and the absorption as well as PL spectra were both red shifted. Moreover, core/shell QDs with alloyed shell were prepared by successive ion layer adsorption and reaction (SILAR) method. Samples were tested by UV, PL, XRD and HRTEM. And the results indicated that both the absorption and PL spectra were red shifted along with the increase of alloyed shell, the longest emission wavelength here was 630.4nm, the FWHM range was between 25nm and 35nm, and the highest QY of all core/shell QDs had been improved to 50.3%.2. A kind of multidentate polymer PGA-g-MEA based on amino acid was successfully self-synthesized. It was used to prepare water-soluble QDs with an identical small size of about 10nm, as well as better pH and thermal stability and lower cytotoxicity. By congujating with goat anti-human IgG, the water-soluble QDs applied as fluorescent probes could accurately and specifically indentify human IgG.3. Fluorescent magnetic nanoparticles were prepared by employing amino groups on the surface of silica-coated QDs to ring open the acid anhydride on surface of Fe3O4 nanoparticles. And the fluorescent and magnetic properties of the nanoparticles were characterized by UV-Vis, PL, HRTEM and VSM .etc. The results indicated that the fluorescent magnetic nanoparticles with better PL intensity and better magnetic property were successfully prepared.The study will provide important experimental basis to application of QDs in diagnosis.