The Synthesis Of Fluorescence Probes Based On Quantum Dots And Their Application For Bioimaging In Vitro And In Vivo

Bioimaging technique is a very important means for diagnosis and treatment of diseases. Because of the close relationship to human health, it has become one ofthe most popular research fields recently. Great progresses have been made on the research on imaging probes due to the development of bioimaging technique. Building high-quality imaging probes not only provide the material basis for the bioimaging research and promote development and progress on biology and medicine, but also promote chemistry, materials science and other disciplines development. So it has significant research value and practical significance.Quantum dots (QDs) are a class ofsemiconductor nanocrystals which three-dimensional size is located in nanoscale. As an emerging nano fluorescent probe, quantum dots have many advantages such as broad excitation spectra, narrow emission spectra, high quantum yield, high chemical stability and light stability, excellent water solubility and good biocompatibility, etc. Thus, they are the ideal bioimaging probes. In thisthesis, we took much attention on preparing high-quality water-soluble quantum dots as imaging probes, and synthesized several new type near-infrared fluorescence imaging probes and fluorescent/magnetic resonance bimodality imaging probes based on quantum dots.This thesis consists ofsix chapters. In Chapter1, the general introduction including the development of bioimaging technique, applicationof nano imaging probes, the basic knowledge and the development of magnetic quantum dots in multimodality imaging was described in details. Additionally, the aim and significance of this thesis were also briefly presented.In Chapter2, near-infrared emitting Cu-doped CdS quantum dots was prepared directly in aqueous solution. A series of quantum dots with different emission wavelenthes were obtained by controlling thereaction conditions such as the incorporation of Cu2+ions, reaction temperature, the amount of stabilizer and the pH of the reaction system. The as-prepared quantum dots have excellent fluorescent properties and are successfully employed in the study of biological imaging in living cells. In Chapter3, near-infrared emitting Mn-doped Ag2S quantum dots (Mn:Ag2S QDs) were directly synthesized in aqueous solution at room temperature by a facile method. Mn:Ag2S QDs were successfully employed in the fluorescence imaging studies in vivo. The characteristics of the work are as follows:(1) the incorporation ofMn2+ions can enhance the fluorescence intensity of Ag2S quantum dot;(2)Mn-doped Ag2S QDs can retain near-infrared emitting after the incorporationofMn2+ions by control theamountofMn2+ions;(3) it can accumulate some experience for incorporating Mn2+ions into the quantum dots with narrow bandgap.In Chapter4, Mn2+doped CdTe QDs were prepared by a simple hydrothermal method with a surfacecation exchange process. The as-prepared QDs have both excellent fluorescent and magnetic properties and have been sucessfully used in fluorescence imaging study in MCF-7cells. And its possibilities as a magnetic resonance imaging probes was also discussed.In Chapter5, Gd-doped CdTe QDs were synthesized by a simple aqueous method at room temperature. The preparation method was simple and facile for the operationwithout heating. The fluorescence propertyof the as-prepared QDs was only controled by the ratio of thereactants without any relationship to the other reaction conditions. The as-prepared QDs with small particle size have excellent fluorescence quantum yield, water soluble, biocompatible and magnetic properties. After the conjunction with folic acid on the surface of the QDs, they were successfully employed in the tumor targeted fluorescent/magnetic resonance bimodality imaging both in vitro and in vivo.In Chapter6, CdTe@GdScore-shellnanoparticles were synthesized in aqueous solution following the preparation method described in Chapter5. Compared with the Gd-doped CdTe QDs, CdTe@GdS core-shell nanoparticles contained more Gd3+ions, which can significantly enhance the paramagnetic natureof the nanoparticles. Thus, they not only retain the excellent fluorescence propertiesof CdTe QDs, but also have more excellent magnetic properties for the tumor targeted fluorescent/magnetic resonance bimodality imaging both in vitro and in vivo.