Novel And Highly Effective Rare-earth Doped Spectral Converter And Its Biological Applications

Superior light, electric, manetic properties promote nanoparticles developmentin the biosensor and solar cell applications. Among them, rare-earth dopednanoparticles, which show attractive charm in biological fluorescence detection andsolar spectrum conversion, have become one of the hot issues of spectra-physics andnano-materials field. Thus, in this work we studied the luminescence properties oflanthanide doped nano-phosphors, developed novel, highly effective lanthanidedoped nano-material structures, and studied on its applications of biologicalfluorescence detection. The main results are:[1]Visible to near-infrared quantum cutting in NaYF4:Yb3+, Er3+with differentsizes and different concentrations under multi-wavelengths excitation were studied.Based on the excitation and emission spectra, multi processes of quantum cuttingwere concluded. In addition, the studies on luminescent dynamics show that thehighest energy transfer efficiency from Er3+to Yb3+is68.2%. For the infraredquantum cutting emissions the overall efficiencies were estimated to be as high as186-193%.[2]YVO4: Bi3+/Nd3+, Yb3+were synthesized by the solvothermal method, and theemission spectra and decay curves evidenced the ET from Bi3+/Nd3+to Yb3+, then astrategy was established for calibrating the actual QE of QC process in Bi3+/RE3+codoped with Yb3+system. The actual QE of YVO4:5%Bi3+,Yb3+excited with355nm and YVO4:1%Nd3+,10%Yb3+excited with467nm were calculated, which wasmuch lower the estimated values by luminescent dynamics.[3] Novel visible and infrared broad bands were observed in Ln2O3(Er2O3,Pr2O3, Nd2O3, Sm2O3) in air under980-nm excitation. Sufficient cross-relaxationprocesses and photon avalanche processes play important roles in the formation of efficient broad bands. This work suggests that the Ln2O3is a potential candidate forthe development of integrated waveguide broad gain devices.[4]A new type of lead biosensor was developed based on the FRET from UCNPsto QDs, which overcomes the lack of NIR-excitable probes for lead ion. The sensorwas applied to determine the lead ion in human serum with good linear relationship(R=0.996), low detection limit (80nM), moreover, the biosensor is capable ofovercoming self-luminescence[5]Some novel composite films, NaYF4:Yb3+,Tm3+(Er3+)/TiO2IOPCs werefabricated by the self-assemble technique. By the modulation of TiO2IOPCs, highlyenhanced emissions of Tm3+/Er3+were observed in the composite films under980-nm excitation. An optimum EF of43-fold was obtained for the UCL of5-nm-NaYF4:Yb3+, Tm3+NCs composite film with this strategy. Moreover, based onthis unique structure, specific interaction between biotin and avidin, and FRETbetween Tm and FITC, the UC composite film was used for detecting avidin andobtained good linear relationship (R=0.996), low detection limit (48pmol), highsensitivity (34pmol-1), and photostability.[6] Paper-based analytical devices were fabricated based on the nano-printingtechnology and upconversion floursence resonnent energy transfer for detectingCEA. The sensor was applied to determine CEA with good linear relationship(R=0.998), low detection limit (0.89ng/mL), and portability.