Biofunctionalization of CeF3 : Tb3+ nanoparticles

CeF3: Tb3+ nanoparticles (short pillar-like morphology with an average length and width of 11 and 5 nm, respectively) were successfully prepared by a polyol process using diethyleneglycol (DEG) as solvent. After being functionalized with a SiO2-NH2 layer, these CeF3: Tb3+ nanoparticles can be conjugated with biotin molecules (activated by thionyl chloride) and further with avidin. The as-formed CeF3: Tb3+ nanoparticles, CeF3: Tb3+ nanoparticles functionalized with amino groups, biotin conjugated amino-functionalized CeF3: Tb3+ nanoparticles and biotinylated CeF3: Tb3+ nanoparticles bonded with avidin were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), UV/vis absorption spectra and luminescence spectra, respectively. The biofunctionalization of the CeF3: Tb3+ nanoparticles has less effect on their luminescence properties, i.e. they still show strong green emission (from Tb3+, with D-5(4) - F-7(5) at 543 nm as the most prominent group), indicative of the great potential for these CeF3: Tb3+ nanoparticles to be used as biological fluorescence probes.

Synthesis and chain-length dependent properties of monodisperse oligo(9,9-di-n-octylfluorene-2,7-vinylene)s

A series of monodisperse oligo(9,9-di-n-octylfluorene-2,7-vinylene)s (OFVs) with fluorene units up to 11 has been synthesized following a divergent approach. Chain length was found to affect not only photophysical properties but also thermal properties. Absorption and photoluminescence spectra are red-shifted with increasing chain length. The effective conjugated length has been extrapolated to be as long as 19 fluorene vinylene units, indicative of a well-conjugated system. With the number of fluorene units > 5, the oligomers exhibit nematic mesomorphism. Glass transition temperature (T-g) and clearing point temperature (T-c) increase with increasing molecular length and with those of OFV11 up to 71 and 230 degrees C, respectively. The oligomers can form uniform films by solution casting for fabrication of light-emitting diodes. With a device structure of ITO/ PEDOT:PSS/OFV11/Ca/Al, a current efficiency of 0.8 cd.A(-1) at a brightness of 1300 cd.m(-2) along with a maximum brightness of 2690 cd.m(-2) have been realized. This performance is notably superior to that of the corresponding polymer.

Reduction from Eu3+ to Eu2+ in BaAl2O4 : Eu phosphor prepared in an oxidizing atmosphere and luminescent properties of BaAl2O4 : Eu

A reduction phenomenon of Eu3+ -> Eu2+ was observed for the first time when Eu3+ ions were doped into an AlO4-tetrahedron-containing compound BaAl2O4 in an oxidizing atmosphere of air by high-temperature solid-state reaction. X-ray powder diffraction patterns and photoluminescent spectra are used to confirm the compound structure and detect the simultaneous existence of both divalent and trivalent europium ions, respectively. The abnormal Eu3+ -> Eu2+ reduction is explained by a charge compensation model. Spectroscopic properties of BaAl2O4:Eu are discussed and Eu2+ emission spectrum shows consistence with the results reported by Katsumata et a]. [J. Cryst. Growth 198/199 (1999) 869.] and Lin et al. [Mater. Chem. Phys. 70 (2001) 156.].

The magnetic and structural properties of hydrothermal-synthesized single-crystal Sn1-xFexO2 nanograins

The crystal structure and magnetic properties of Sn1-xFexO2 nanograins synthesized by simple hydrothermal method using SnCl4 center dot 5H(2)O and FeCl3 center dot 6H(2)O as raw materials are studied. No secondary phase was found in the XRD spectrum. The linear change of lattice volume for different Fe content strongly supports that the Fe3+ substitutes Sn4+ in SnO2 lattice. A Raman and IR spectra study indicated that the Fe incorporates into the SnO2 lattice. Both ferromagnetic and paramagnetic signals are detected in the Mossbauer spectra. The Sn1-xFexO2 (x <= 0.10) samples show room-temperature ferromagnetism (RTFM) and the saturation magnetization increased with increasing Fe percent. Fe ions present three kinds of magnetic behaviors including paramagnetic, ferromagnetic, and antiferromagnetic in the samples observed by investigation of the M-H and M-T curves. The weak RTFM was due to only a fraction of Fe ions contributing to magnetic-order coupling mediated by oxygen vacancy.

Oriented growth and luminescence of ZnO : Eu films prepared by sol-gel process

A series of Eu3+-doped ZnO films have been prepared by a sol-gel method. These films were characterized by X-ray diffraction (XRD) and photoluminecent spectra (PL). Effects of synthetic parameters, such as annealing atmosphere, temperature and concentration of doped ions, on the highly oriented crystal growth were studied in detail. The crystalline structures of films annealed in vacuum have a wurtzite symmetry with highly c-axis orientation. A characteristic D-5(0) -> F-7(J)(J = 1, 2, 3 and 4) red emission is observed due to energy transfer from the ZnO host to the doped Eu3+ in the c-oriented ZnO films.

Interaction between La3+ and MP-11 in the physiological solution

In this paper, the interaction between La3+ and microperoxidase-11 (MP-11) in the imitated physiological solution was investigated with the electrochemical method, circular dichroism (CD) and ultraviolet-visible (UV-vis) absorption spectroscopy. It was found that the interaction ways between La3+ and MP-11 are different with increasing the molar ratio of La3+ and MP-11. When the molar ratio of La3+ and MP-11 is less than 2, La3+ mainly interacts with the metacetonic acid group of the heme group in the MP-11 molecules, causing the increase in the non-planarity of the porphyrin cycle in the heme group and the decrease in the content of the random coil conformation of MP-11. These structural changes would increase the exposure extent of the electrochemical active center of MP-11 and thus, La3+ can promote the electrochemical reaction of MP-11 and its electrocatalytic activity for the reduction of H2O2 at the glassy carbon (GC) electrode. However, when the molar ratio of La3+ and MP-11 is larger than 3, except binding to the carbonyl oxygen of the metacetonic acid group in the heme group, La3+ interacts also with the oxygen-containing groups of the amides in the polypeptide chains of the MP-11 molecules, leading to the increase in the contents of the random coil conformation in the peptide of the MP-11 molecule, comparing with that for the molar ratio of less than 2.

Synthesis and luminescence properties of Gd2O3 : Eu3+ phosphors

Gd2O3: EU3+ phosphors were prepared by urea homogeneous precipitation with different surfactant and sol-gel method. XRD patterns show that all the obtained samples are in cubic Gd2O3, and the results of FTIR and fluorescent spectra conformed that OP is a good surfactant for preparing the Gd2O3: Eu3+ phosphors. The SEM photographs show that the particles prepared by urea homogeneous precipitation method are all spherical and well-dispersed, and grain morphology can be controlled by different surfactant. XRD and SEM indicate that the particle sizes prepared by sol-gel method are in the range of 5 similar to 30 nm, and the grain sizes increase with increasing of heated temperatures. Luminescence spectra indication that the main emission peaks of all samples are at 610 nm, the intensities are different from samples prepared with different surfactant and the luminescence intensities increase with increasing of annealed temperatures.

Synthesis and photoluminescence of the Y2O3 : Eu3+ phosphor nanowires in AAO template

The monodisperse array and nanowires Of Y2O3:Eu3+ phosphor were synthesized using anodic aluminum oxide (AAO) template by sol-gel method. Scanning electron microscope (SEM) images indicated that Y2O3:Eu3+ nanowires are parallelly arranged, all of which are in uniform diameter of about 50 nm. The high-magnification SEM image showed that each nanowire is composed of a lot of agglutinating particles. The patterns of selected-area electron diffraction confirmed that Y2O3:EU3+ nanowires mainly consist of polycrystalline materials. Excitation and emission spectra Of Y2O3:E U3+/AAO composite films were measured. The characteristic red emission peak of EU3+ ion attributed to D-5(0)-->F-7(2) transition in Y2O3:EU3+/AAO nanowires broadened its halfwidth.

Synthesis and characterization of SiO2/Gd2O3 : Eu core-shell luminescent materials

Europium-doped Gd2O3 with an average size of similar to15 nm was coated on the surface of preformed silica nanospheres by the wet chemical method. SEM and TEM photographs showed that SiO2/Gd2O3:Eu core-shell submicrospheres are obtained. XRD patterns indicated that the Gd2O3:Eu shell is crystalline after heat treatment. FTIR and XPS spectra showed that the Gd2O3:Eu shell is linked to the silica surface by forming a Si-O-Gd bond. Photoluminescence studies showed that the luminescent properties are still retained after coating on an inert silica core; additionally, we noted that the emitting peaks are broadened, which results from size effects and interface effects of nanocrystal.

Citrate-gel synthesis and luminescent properties of alpha-Zn-3(PO4)(2) doped with Eu3+

By using inorganic salts as raw materials and citric acid as complexing agent, alpha-Zn-3(PO4)(2) and Eu3+ doped alpha-Zn-3(PO4)(2) phosphor powders were prepared by a citrate-gel process. X-ray diffraction, (XRD), TG - DTA, FT - IR and luminescence excitation and emission spectra were used to characterize the resulting products. The results of XRD reveal that the powders begin to crystallize at 500 degreesC and pure alpha-Zn-3(PO4)(2) phase is obtained at 800 degreesC. And the results of XRD reveal that Eu3+ exists Lis EoPO(4) ill the powder. In the phosphor powders, the Eu3+ shows its characteristic red-orange (592 nm, D-5(0) - F-7(1)) emission and has no quenching concentration.

稀土铽离子对辣根过氧化物酶活力指数的影响

The effect of Tb3+ ion on the Activity Index (RZ=A403/A275) of HRP was investigated by a combination of ultraviolet-visible, FT-infrared and X-ray photoelectron spectroscopic techniques. It was found that Tb3+ ion could bond to the O and/or N group of the amides in the polypeptide chains of HRP, leading to a decrease in the enzymatic activity index of HRP.

Grafting polymerization of L-lactide on the surface of hydroxyapatite nano-crystals

A novel method of grafting ring-opening polymerization of L-lactide (LLA) onto the surface of hydroxyapatite nano-particles (n-HAP) was developed. PLLA was directly connected onto the HAP surface through a chemical linkage. The PLLA-g-HAP particles could be stably dispersed in organic solvent such as chloroform for several weeks. The n-HAP particles still retained the original dimension and shape after the grafting of PLLA. Compared with the P-31 MAS-NMR spectrum of pure HAP powders, there appeared a downfield displacement of 1.2 ppm in the spectrum of PLLA-g-HAP. Fourier transformation infrared (FT-IR) spectra further confirmed the existence of PLLA on the surface of PLLA-g-HAP. The amount of grafted polymer determined by thermal gravimetric analysis (TGA) was about 6% in weight. The tensile strength and elongation at break of the PLLA/PLLA-g-HAP composite containing 8 wt% of PLLA-g-HAP were 55 MPa and about 10-13%, respectively, while those of the PLLA/n-HAP composites were 40 MPa and 3-5%, respectively.

Preparation and luminescence properties of in situ formed lanthanide complexes covalently grafted to a silica network

Lanthanide-doped sol-gel-derived materials are an attractive type of luminescent materials that can be processed at ambient temperatures. However, the solubility of the lanthanide complexes in the matrix is a problem and it is difficult to obtain a uniform distribution of the complexes. Fortunately, these problems can be solved by covalently linking the lanthanide complex to the sol-gel-derived matrix. In this study, luminescent Eu3+ and Tb3+ bipyridine complexes were immobilized on sol-gel-derived silica. FT-IR, DTA-TG and luminescence spectra, as well as luminescence decay analysis, were used to characterize the obtained hybrid materials. The organic groups from the bipyridine-Si moiety were mostly destroyed between 220 and 600 degreesC. The luminescence properties of lanthanide bipyridine complexes anchored to the backbone of the silica network and the corresponding pure complexes were comparatively investigated, which indicates that the lanthanide bipyridine complex was formed during the hydrolysis and co-condensation of TEOS and modified bipyridine. Excitation at the ligand absorption wavelength (336 nm for the hybrid materials and 350 nm for the pure complexes) resulted in strong emission of the lanthanide ions: Eu3+ D-5(0)-F-7(J) (J = 0, 1, 2, 3, 4) and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) emission lines due to efficient energy transfer from the ligands to the lanthanide ions.

Combustion. synthesis and luminescence properties of nanocrystalline monoclinic SrAl2O4 : Eu2+

Nanocrystals of SrAl2O4:Eu2+ have been prepared by combustion synthesis. The results of XRD indicated that the resulting SrAl2O4:Eu2+ nanocrystals have a reduced and distorted monoclinic lattice compared with bulk materials. Both the excitation and emission spectra of SrAl2O4:Eu2+ nanocrystals shifts to higher energies in contrast to the bulk materials. The band structure calculation is performed using first-principles full potential-linearized augmented plane wave method within density functional theory. The calculated results are in reasonable agreement with our experimental results.

Crosslinkable poly (p-phenylenevinylene) derivative

To simplify the fabrication of multilayer light-emitting diodes, we prepared a p-phenylenevinylene-based polymer capped with crosslinkable styrene through a Wittig reaction. Insoluble poly(p-phenylenevinylene) derivative (PPVD) films were prepared by a thermal treatment. The photoluminescence and ultraviolet-visible (UV-vis) absorbance of crosslinked films and noncrosslinked films were studied. We also studied the solvent resistance of crosslinked PPV films with UV-vis absorption spectra and atomic force microscopy. Double-layer devices using crosslinked PPVD as an emitting layer, 2-(4-tert-butylphenyl)-5-phenyl-1,3,4-oxadiazole (PBD) in poly(methyl methacrylate) as an electron-transporting layer, and calcium as a cathode were fabricated. A maximum luminance efficiency of 0.70 cd/A and a maximum brightness of 740 cd/m(2) at 16 V were demonstrated. A 12-fold improvement in the luminance efficiency with respect to that of single-layer devices was realized.