The Synthesis And Modification Of CdTe/CdS Near-infrared Emission Quantum Dots And Its Applications In Two-photon Excitation Microscopy

During to the high quantum yields (QY) and wide range of emission wavelength from 475nm to 810nm, water-soluble CdTe/CdS quantum dots can play an important role in bioimaging, especially in tumor and vivo imaging. Until now, the synthetic approach in organic phase have no intrinsic aqueous solubility, and the QY will significant decrease during the phase transfer. On the other hand, aqueous phase synthetic strategy need many steps and waste too much time. Therefore, this article introduced a microwave assisted method to synthesize water-dispersed CdTe/CdS quantum dots with high QY rapidly. And then it was coated by silica through conventional W/O microemulsion method to reduce its toxicity. The main contents and results are as follows:1. Near-infrared CdTe/CdS QDs with high QY (71.5%), small size and good two-photon absorption cross-section, was prepared by microwave-assisted one-step synthesis route. Ultraviolet-visible (UV-vis) absorption spectra, photoluminescence spectra (PL), dynamic light scattering (DLS) and two-photon excitation fluorescence spectra were used to characterize the size and physical properties of QDs.2. The pre-synthesized QD690 which was functionalized with MPA, was mixed with TEOS and surfactant molecules. And thus the silica coated QDs was successfully synthesized. By the optimization of water content, concentration of QDs, and the adding of PDDA ect, nano fluorescent microspheres with uniform size, good dispersion and high fluorescence intensity was achieved.3. The cell toxicity of QD690 and CdTe@CdS@SiO2 were measured by MTT method. After successfully coupled with holo-Tf we investigated the applications of QD-holo-Tf and CdTe@CdS@SiO2-holo-Tf in cell imaging. e demonstrated the for targeted HeLa cells.Above all, microwave-assisted one-step synthesis of highly fluorescent and ultrasmall size CdTe/CdS QDs with broadly tunable near-infrared emission was reported. And nontoxic nano fluorescent microspheres was prepared.The two probes allowed high-sensitive imaging in bioanalysis.