Synthesis And Biological Properties Of Composite Upconversion Nanocrystals For Gene Vector

In recent years, rare-earth ion doped upconversion nanomaterials have been studied and applied extensively in the biotechnology field because of their unique optical properties. In this thesis, infrared-to-visible upconversion fluorescence nanoparticles, rare earth ions Yb3+and Er3+co-doped sodium yttrium fluoride (NaYF4), were synthesized. Through the research of the interaction between nanoparticles synthesized and nucleic acid, provides a performance of nucleus material for non-viral gene vectors.The thermal decomposition synthesis process was used to prepared Yb3+and Er3+co-doped hexagonal phase NaYF4nanoparticles (β-NaYF4:Yb, Er) stabled with oleic acid. Three kinds of products were obtained by changing the reaction conditions. The crystalline phase, morphology, optical properties and surface properties of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope, fluorescence spectrum (FL) and Fourier transform infrared (FTIR) spectrometer, respectively. The results confirmed that three kinds of different morphologies but the same crystalline phase structure β-NaYF4:Yb, Er nanoparticles were obtained. Under980nm excitation, all of the products show bright upconversion fluorescence. Each kind of the products was obtained with uniform morphology and size. The resulting morphologies of nanoparticles:Spherical particles with a particle diameter about25nm, hexagonal particles with size about40nm, nanorods with20nm in length and40nm in diameter. Ligand oxidation reaction was used to changing oleic acid to azelaic acid to obtain carboxyl functionalized water-soluble nanocrystals. Water-soluble nanocrystals were also obtained through surface ligands exchange reaction which converts oleic acid to tri-sodium citrate. Analysis showed that the processes of ligand oxidation and exchange did not play a significant role on the crystalline phase and morphology of nanocrystals. Preliminary gold coated experiment is carried on carboxyl-modified nanocrystals. The results showed that the effect of gold coated nanoparticles used for nucleic delay with cationic liposomes in common was better than using cationic liposomes alone.