Synthesis Of YBO₃:Tb Fluorescent Molecular Probes And Their Application In Biological Analysis

In spite of the unique optical properties of fluorescent molecular probes, such as large stokes shift, high fluorescence emission intensity, narrow half emission peaks, long fluorescence lifetime, stable physical and chemical properties, high color purity and so on, lanthanide-doped luminescent nanoparticles have a good prospect in immunoassays, DNA tests and cellular imaging. Using fluorescence resonance energy transfer technology(FRET) for detection of biological molecules have many advantages, such as fast reaction speed, high sensitivity and resolving capability, easy and simple to handle and so on. Therefore, The rare-earth fluorescent molecular probes were used in FRET to determine biological macromolecules, has attracting more and more researchers’ attention.We developed a method to prepare the biocompatible YBO3：Tb nanoparticles with functional chemical groups of the sodium citrate. The effects of experimental conditions on fluorescent performances of YBO3:Tb nanoparticles were also studied. The best conditions to synthesize YBO3:Tb nanoparticles were as follows:the initial reactant concentration were0.1mol/L; the mole ratio of lanthanide ions to H3BO3was1:1; the Eu3+doped content was20%; the volume sodium citrate was5ml, corresponds to the volume fraction of0.36; the pH of the mixed solution of rare earths and H3BO3was10.0and the whole reactants reacted at160℃for6h. The prepared YBO3:Tb nanoparticles also have high fluorescence intensity and stable optical properties. The fluorescence lifetime of the YBO3:Tb nanoparticles was1.53ms and the maxmium excitation and emssion wavelengths were234nm and545nm, respectively.The prepared YBO3:Tb particles were characterized by many methods. The results of IR showed that the surface of the YBO3:Tb nanoparticles were coated with sodium citrate; TEM image indicated that the shape of the nanoparticles were uniform, but was not well dispersed. XRD pattern showed that the as-prepared YBO3:Tb particles were non-crystalline. Using the lysozyme as bridge, as-prepared YBO3：Tb nanoparticles and Au NPs to form a new FRET system. The effects of experimental conditions on the system were also studied. The best conditions were as followed:borate saline buffer(pH=7.4); the adding volumes of YB03:Tb(5×10-3mol/L) nanoparticles and Au NPs were200μL and400μL, respectively. When the concentration of LZM changed from0-33.3μg/ml, there was a good linear relation between the concentration of the LZM and the intensity of particles. The Linear equation was I=415-0.16c with a cor relation coefficient of0.9921.A FRET system was constructed, where the Au NPs conjugated with human immunoglobulin G(IgG) was the energy donor and the YBO3：Tb NPs conjuated with rabbit anti-goat IgG was the energy acceptor, repectively. This NP-based FRET system was then used to determine the amount of goat anti-human IgG in a sandwich-type bioananlysis. The experiment result demonstranted that the linear relationship of I=783-3.11c with a correlation cofficient of0.9910between the intensity of YBO3：Tb solution(I) and the concentration of goat anti-human IgG(C) was obtained, when the concentrati on of goat anti-human IgG(C)changed from1.6to60μg/mL, Statitical analysis revealed that the detection limit of goat anti-human IgG concentration was1.0μg/mL(3a/N) obtained from a series of11standard samples with eath containing2.0μg/mL goat anti-human IgG. In conclusion, the results demonstranted that the sensitivity of the decection was high relatively.