Aqueous Controllable Synthesis Of Thick-shell Quantum Dots And Their Application For Cellular Labeling

In this thesis, a series of CdTe/CdS core/shell quantum dots (QDs) with different numbers ofmonolayers of CdS shell were synthesized through one-pot microwave irradiation in aqueoussolution accurately, and even the thick-shell nanocrystals could be obtained within a short time.Then we used the bio-functionalized CdTe/CdS NCs which the emission wavelength was700nm tolabel the human adenocarcinoma549in near infrared region. At last, CdTe/ZnSe core/shellnanocrystals were prepared by successive ion layer adsorption and reaction (SILAR). The maincontents of the thesis are summarized as follows:1. CdTe/CdS core/shell nanocrystals with different shell thickness were synthesized controllableby the one-pot approach assisted by microwave irradiation, and the core/thick-shell NCs could besynthesized specially. Previous thick-shell NCs were obtained by multistep high-temperatureorganometallic approaches which are disadvantageous for experimental operation. Herein, wedescribe a method, in which CdTe/CdS NCs (1-11monolayers) with emission wavelength fromvisible to near infrared region were obtained within15mintues on the basis of regulating thetemperature, and the influence of the reaction conditions on the growth mechanism andphotoluminescent properties of the QDs were studied. The optical properties of the products wereanalyzed by UV-vis-near-infrared spectrophotometer (UV-vis), Photoluminescence (PL) and thefluorescence lifetime and steady state spectrometer. The morphology, structure, and composition ofCdTe/CdS core/shell nanocrystals were characterized by Transmission electron microscopy (TEM),high-resolution transmission electron microscopy (HRTEM), X-Ray photoelectron spectroscopy(XPS) and Powder X-ray diffraction (XRD). The experimental results show that the productspossessed giant spectral shifts (530-920nm), extended excited-state lifetimes, high quantum yields(85%) and excellent optical stability when the CdS shell grow thicker.2. The highly photoleminescent CdTe/CdS core/shell quantum dots with emission at700nm inthe near-infrared window were synthesized by the optimum reaction conditions, then theas-prepared QDs were used to label the human lung adenocarcinoma A549cell specifically afterQDs linked to RGDyk or aptamer. The results indicate that the QDs-RGDyk fluorescent probeslabeled the membrane and cytoplasm of A549, and the QDs-aptamer fluorescent probes labeled themembrane of the cells successfully in near infrared region.3. CdTe/ZnSe core/shell QDs were directly synthesized in the aqueous condition by SILAR and controlling the reaction conditions, characterization results with TEM and PL have shown thatCdTe/ZnSe QDs have good monodispersity and excellent optical performance. Furthermore, thecytotoxicity of Zn2+is much less than that of Cd2+, which makes these QDs apply to in vivoimaging.