Synthesis Of YVO₄:Eu Nanoparticles And Their Application In Fluorescence Resonant Energy Transfer

In recent years, the analysis and detection technology by using lanthanide-doped luminescent nanoparticles as markers has gained considerable attention due to their unique optical properties, such as large Stokes shift, high fluorescence emission intensity, narrow half emission peaks, long fluorescence lifetime, and so on. Lanthanide-doped luminescent nanoparticles have showed important applications in high-resolution displays, integrated optical system, solid laser, biological analysis, and medical diagnosis. The use of these special nanoparticles as biological markers can improve the sensitivity and selectivity of the detection.We developed an in situ surface modification method to prepare the biocompatible lanthanide-doped luminescent nanopartieles with functional chemical groups of the organic regents in a one-pot synthesis process. Poly acrylic acid (PAA) capped YVO4:Eu nanopartieles were synthesized by using this method. The effects of experimental conditions on fluorescent performances of YVO4:Eu nanoparticles were also studied. The best conditions to synthesize YVO4:Eu nanoparticles were as follows:the mole ratio of lanthanide ions to Na3VO4was1:1, the Eu3+doped content was0.25, the volume fraction of PAA was0.6, the pH of the solution was9.5, and the whole reactants reacted at150℃for4h. The fluorescence lifetime of the YVO4:Eu nanoparticles was0.709ms, the quantum yield was6.27%, the nanoparticles also have a good stability of fluorescence.The prepared YVO4:Eu particles were charactered by many methods. From the fluorescence emission spectra we can get that the strong peak at618nm attributed to the5Doâ†'7F2transition of Eu3+; the results of IR showed that the surface of the YVO4:Eu nanoparticles were coated with PAA; the XRD pattern showed that the as-prepared YVO4:Eu particles were tetragonal and well-crystallized with an average diameter of22.4nm; TEM image indicated that the nanoparticles were well dispersed and the shape was uniform.Using YVO4:Eu as energy donor in the Fluorescence Resonant Energy Transfer (FRET), we have found a new method for quantitative detection of Malachite Green (MG). When the pH was5.0, the concentration of YVO4:Eu nanoparticles was2.0×10-5mol·L-1, the relationship between the concentration of MG and the intensity of YVO4:Eu solutions accorded with modified Stern-Volmer equation, the linear regression equation was lgl=2.965-0.185c with a correlation coefficient of0.9973and the detection range was5.00×10-5～5.00×10-3g·L-1, the detection limit was2.0×10-5g·L-1, the recovery in water samples was well by adding standard MG solution into water.We used the as-prepared YVO4:Eu fluorescent nanoparticles and phycocyanin (PC) to form a new FRET system and investigated their interaction roughly. When the concentrations of YVO4:Eu nanoparticles and PC were2.0×10-5mol·L-1and0.010mg·mL-1respectively, adding200μL EDC and involving a activation for2h can achieve an higher energy transfer efficiency.