Preparation And Applications Of Rare-earth Doped Upconversion Luminescent Nanomaterials And Superparamagnetic Ferroferric Oxide Nanoparticles

Due to their small size,nanomaterials have large specific surface area and high proportion of atoms on the surface.The performance of nanomaterials are affected by quantum size effect,small size effect and surface-interface effect,which causes their unique magnetic,thermal,luminescent and electrical properties.In several decades,nanomaterials have gradually become one of the research focuses,and foothold of interdisciplinarity innovation.Among various nanomaterials,rare-earth doped upconversion luminescent nanomaterials and superparamagnetic ferroferric oxide nanoparticles have attracted more and more researchers since their broad application prospects in biomedical fields.This dissertation employed potassium sodium tartrate assisted hydrothermal method to synthesis a series of rare-earth doped upconversion luminescent nanomaterials,including BaLuF₅:Yb³⁺/Er³⁺,BaGdF₅:Yb³⁺/Er³⁺and BaYF₅:Yb³⁺/Er³⁺.In the stirring stage before hydrothermal process,potassium sodium tartrate promote reagents to form complexed precursor with 3D network structure.This structure is efficient to restrain the savage growth of grains in hydrothermal process.Finally,sphere nanoparticles with diameter of 25³0 nm are obtained.These prepared nanoparticles connect with organic groups on the surface,enhancing water solubility and accessibility to couple with other molecules.The result of cell toxicity experiment by MTT method determined the good biocompatibility of the products.The study of in vitro and in vivo CT and MR imaging were conducted.Relevant images indicate the enhancements of BaYF₅:Yb³⁺/Er³⁺upconversion luminescent nanomaterials to CT and MR imaging effects,proving these nanoparticles can serve as the unite contrast agents of CT and MR imaging.This dissertation also adopted ascorbic acid assisted hydrothermal method to prepare superparamagnetic ferroferric oxide nanoparticles.Ascorbic acid self-oxidized to dehydroascorbic acid to restrain the oxidation of Fe²⁺.Meanwhile,dehydroascorbic acid molecules connect to ferroferric oxide molecules by forming complex,which can control the size of nanoparticles and get good water solubility and versatility.Magnetic measurements reveal the excellent superparamagnetic property of prepared nanoparticles.The imaging effect of in vivo MR imaging was improved remarkably by injecting a certain amount of prepared superparamagnetic ferroferric oxide nanoparticles,indicating the feasibility to employ these nanoparticles as MR imaging contrast agent.