Preparation And Fluorescence Properties Of Rare Earth (La³⁺,Nd³⁺,Eu³⁺,Gd³⁺)-doped Bioimaging Nanomaterials

Imaging technology plays a crucial role in the fields of molecular biology, cytology andclinical diagnosis. Imaging materials with superior properties can enhance the contrast and theresolution of the image. As a result, sophisticated images can be presented and more biologicalinformation can be obtained.The applications of traditional organic fluorescent dyes are limited due to its poorphotochemical stability, broad absorption and emission bands, photobleaching and photolysis.Meanwhile, photolytic products often have a lethal effect on the organism. Besides, the fluorescentsemiconductor nanocrystals are extensively studied in recent years. Howerer, its applications arestill subject to some restrictions because of the poor chemical stability and toxicity. In contrast, therare earth nanomaterials with unique optical, electrical, magnetic properties and low biologicaltoxicity, have broad application prospects in biological imaging technology.Based on the previous study, a series of rare earth nanomaterials with different size,morphology and fluorescence properties were synthesized by hydrothermal method. The structures,morphologies and fluorescence properties of these nanomaterials are further characterized andanalyzed. Moreover, the possible mechanism were investigated. By the use of water-solublepolymers as surface modification agents, functional groups are connected to the surface ofnanoparticles. As a result, water-soluble nanoparticles with near infrared-to-near infraredfluorescence were obtained.This thesis consists of five parts: The first chapter includes a review of the preparationmethods, research hotspots and application progress of rare earth nano-contrast materials. And theresearch purpose of this paper, as well as the main contents are described. In the second chapter,Gd2O3: Eu3+nanorods were prepared by the method of solvothermal-calcination. The effect on themorphology of the reaction time, the pH value and calcination time are studied systematically. Inchapter three, we have synthesized a series of undoped and Nd3+-doped LaxGd1-xF3nanocrystals viaa facile doping-controlled solvothermal method. The results indicated that, by introducing highcontent of La3+(30mol%) into GdF3, orthorhombic GdF3NCs are completely transformed into thehexagonal La0.3Gd0.7F3solid solutions, as far as we know, which have not been reported.Significantly, the morphology of these nanocrystals turned to be nearly-monodispersed nanosphereswith the increasing of La3+-doping concentration. Meanwhile, the near-infrared to near-infrared (NIR-to-NIR) emissions of the Nd3+doping into the NCs are greatly intensified by20%La3+-doping. In chapter four, water-soluble PEI-La0.3Gd0.7F3: Nd3+nanoparticles were prepared bysolvothermal mothod with polyethylenimine as the modifier. And the structure, morphology andoptical properties of the dispersions were further studied. Morever, this polymer-assistedsolvothermal method is proved to be universal in rare earth fluorides preparation. In the last part, wecarried out the summary and outlook of the research work.