Synthesis Of （Y,Gd）₂O₃:Eu Fluorescence Nanoparticles And Its Application In Immunoassay

With the development of the molecular biology researches and clinical medicine, the research and application of the biological labeling materials have become one of the hotpoint in bioanalytical chemisty. As a new type of label, rare earth luminescent markers have the advantages of large Stokes shift、high fluorescence emission intensity, narrow half emission peaks and long fluorescence lifetime. Using of these special nanoparticles as biological analytical markers can improve the detection sensitivity of biological molecules, so they have a broad application prospect. Rare earth oxide nanoparticles is one kind of fluorescent nanoparticles, however, its applications in biological analysis has always been a difficulty. This because the nanoparticles, which can be used for bioanalysis must have small particle sizes, good particle sizes distribution and good water solubility.The synthesis of rare earth oxides must undergo calcined at high temperature, so the nanoparticles are prone to unite, and after high temperature treatment the particles won’t have a water-solubility.Thus, the thesis attempts to prepare water-soluble rare earth oxide nanoparticles and apply them to immunoassay.Here, the (Y,Gd)2O3:Eu fluorescent nanoparticles were synthesized by microemulsion method, and the synthesis conditions were optimized. The results showed that the best conditions to synthesize (Y,Gd)2O3:Eu nanoparticles were as follows:TritonX-100as the sufactant, the volume ratio between surfactant and co-surfactant was2:1, the reaction tempreture for the synthesis of hydroxides precursor was25℃, the reaction time was1.5h, the mole ratio of lanthanide ions to NH3H2O was1:6, both the Gd3+and Eu3+doped contents were10%.The prepared (Y,Gd)2O3:Eu nanoparticles were characterized by many methods. From the fluorescence excitation and emission spectra we can get the strongest peak at262and610nm; the XRD pattern showed that the as-prepared (Y,Gd)2O3:Eu nanoparticles were cubic structure; TEM image indicated that the nanoparticles were well dispersed and the nanoparticle sizes were30-40nm. The fluorescent properties of the (Y,Gd)2O3:Eu nanoparticles colloidal solution had been studied. Results showed that colloidal solution was stable at pH8; the maximum excitation and emission wavelength was253and610nm; the fluorescence lifetime of the (Y,Gd)2O3:Eu nanoparticles was1.11ms, the quantum yield was23%.These (Y,Gd)2O3:Eu nanoparticles were coated with a thin layer of SiO2to form core-shell NPs and further modified with amino groups via a typical Stober method so that it could be water soluble and biocompatible. After surface amino-modification, the nanoparticles were linked with goat anti human IgG and used to determine the amount of goat anti-human IgG. The linear relationship of I=-18.3c+603(the unit of c is μg·mL-1) between the luminescent intensity (I) of (Y,Gd)2O3:Eu nanoparticles and the concentration of goat anti-human IgG (c) was obtained in the range of2-16μg·mL-1,the linear correlation coefficient was0.9915. Statistical analysis revealed that the detection limit (DL) of goat anti-human IgG concentration was0.7μg·mL-1.