Luminescence functionalization of SBA-15 by YVO4 : Eu3+ as a novel drug delivery system

Luminescence functionalization of the ordered mesoporous SBA-15 silica was realized by depositing a YVO4:Eu3+ phosphor layer on its surface via the Pechini sol-gel process, resulting in the formation of the YVO4:Eu3+@SBA-15 composite material. This material, which combines the mesoporous structure of SBA-15 and the strong red luminescence property of YVO4:Eu3+, can be used as a novel functional drug delivery system. The structure, morphology, porosity, and optical properties of the materials were well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, N-2 adsorption, and photoluminescence spectra. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the YVO4:Eu3+ layer and the adsorption of ibuprofen (IBU, drug). The IBU-loaded YVO4:Eu3+@SBA-15 system still shows the red emission of Eu3+ (617 nm, D-5(0)-F-7(2)) under UV irradiation and the controlled drug release property. Additionally, the emission intensity of Eu3+ increases with an increase in the cumulative released amount of IBU in the system, making the extent of drug release easily identifiable, trackable, and monitorable by the change of luminescence. The system has great potential in the drug delivery and disease therapy fields.

Hydrothermal synthesis of SrCO3 : Eu3+/Tb3+ microneedles and their luminescence properties

SrCO3:Eu3+ /Tb3+ microneedles that grow along the a-axis were successfully prepared through a large-scale and facile hydrothermal method without any template and further annealing treatment. X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectra as well kinetic decays, were used to characterize the samples. The preferential growth along a-axis for SrCO3:Eu3+/Tb3+ microneedles has been proposed through analysis of the XRD patterns of samples obtained at different hydrothermal treatment time. Under ultraviolet excitation, the SrCO3:Eu3+ and SrCO3:Tb3+ microncedle samples show a strong red and green emission corresponding to the D-5(0)-F-7(j) (J = 1, 2, 3, 4) transitions of Eu3+ and the D-5(4)-(7) F-j (J = 6, 5, 4, 3) transitions of Tb3+, respectively, which have potential applications in lighting fields.

Luminescence properties of Y0.9-xGdxEu0.1Al3(BO3)(4) (0 <= x <= 0.9) phosphors prepared by spray pyrolysis process

Starting from metal nitrate aqueous solutions and H3BO3, Y0.9-xGdxEu0.1Al3(BO3)(4) (0 <= x <= 0.9) phosphors were synthesized by spray pyrolysis followed by annealing at high temperature. The obtained phosphor particles have spherical morphology with size in the range 0.5-2 mu m. Independent of the x values in Y0.9-xGdxEu0.1Al3(BO3)(4) (0 <= x <= 0.9) phosphors, the Eu3+ ion shows its characteristic D-5(0), (1)-F-7(J) (J = 0, 1, 2, 3, 4) transitions with D-5(0)-F-7(2) red emission (612 nm) as the most prominent group. The photoluminescence intensity of phosphors increases with the increase of x value in Y0.9-xGdxEu0.1Al3(BO3)(4) (0 <= x <= 0.9) due to an energy migration process like Gd3+-(Gd3+)(n)-Eu3+ that occurred in the host materials.

Enhanced luminescence of gadolinium niobates by Bi3+ doping for field emission displays

Blue emitting GdNbO4: Bi3+ powder phosphors for field emission displays were prepared by a solid state reaction. Both photoluminescence and cathodoluminescence properties of the materials were investigated. GdNbO4 itself shows only a very weak luminescence in the blue spectral region. By doping Bi3+ in GdNbO4, the luminescence intensity was improved greatly. The emission spectrum of the GdNbO4: Bi3+ consists of a broad band with maximum at 445 nm (lifetime = 0.74 mu s; CIE chromaticity coordinates: x = 0.1519 and y = 0. 1196) for both UV and low voltage (1-7 kV) cathode ray excitation. In GdNbO4:Bi3+ phosphors, the energy transfer from NbO43- to activator Bi3+ occurred.

Sol-gel deposition and luminescence properties of LiYF4 : Tb3+ thin films

Tb3+-doped LiYF4 films were deposited on quartz glass by a simple sol-gel method. X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), photoluminescence spectra, and lifetimes were used to characterize the resulting films. The results of XRD indicated that the films began to crystallize at 300 degrees C and fully crystallized at 400 degrees C. AFM and FESEM images of singly coated LiY0.95Tb0.05F4 annealed at 400 degrees C indicated that the film is uniform and crack-free films with average grain size of 90 nm, root mean square roughness of 11 nm and thickness of 120 nm. The doped Tb3+ ions showed its characteristic emission in crystalline LiYF4 films, i.e., D-5(3), F--7(4)J (J = 6, 5, 4, 3) emissions. The optimum doping concentration of the Tb3+ was determined to be 5.0 mol% of Y3+ in LiYF4 films.

The luminescence of CaYBO4 : RE3+ (RE=Eu, Gd, Tb, Ce) in VUV-visible region

Phosphors CaYBO4:RE3+ (RE = Eu, Gd, Tb, Ce) were synthesized with the method of solid-state reaction at high temperature, and their vacuum ultraviolet (VUV)-visible luminescent properties in VUV-visible region were studied at 20 K. In CaYBO4, it is confirmed that there are two types of lattice sites that can be substituted by rare-earth ions. The host excitation and emission peaks of undoped CaYBO4 are very weak, which locate at about 175 and 350-360nm, respectively. The existence of Gd3+ can efficiently enhance the utilization of host absorption energy and result in a strong emission line at 314 nm. In CaYBO4, Eu3+ has typical red emission with the strongest peak at 610 nm; Tb3+ shows characteristic green emission, of which the maximum emission peak is located at 542 nm. The charge transfer band of CaYBO4:Eu3+ was observed at 228 nm; the co-doping of Gd3+ and Eu3+ can obviously sensitize the red emission of Eu3+. The fluorescent spectra of CaYBO4:Ce3+ is very weak due to photoionization; the co-addition of Ce3+-Tb3+ can obviously quench the luminescence of Tb3+.

Synthesis and luminescence properties of nanocrystalline Gd2O3 : Eu3+ by combustion process

The nanocrystalline Gd2O3:Eu3+ powders with cubic phase were prepared by a combustion method in the presence of urea and glycol. The effects of the annealing temperature on the crystallization and luminescence properties were studied. The results of XRD show pure phase can be obtained, the average crystallite size could be calculated as 7, 8, 45, and 23 run for the precursor and samples annealed at 600, 700 and 800 degrees C, respectively, which coincided with the results from TEM images. The emission intensity, host absorption and charge transfer band intensity increased with increasing the temperature. The slightly broad emission peak at 610 nm for smaller particles can be observed. The ratio of host absorption to O-2-Eu3+ charge transfer band of smaller nanoparticles is much stronger compared with that for larger nanoparticles, furthermore, the luminescence lifetimes of nanoparticles increased with increasing particles size. The effects of doping concentration of Eu3+ on luminescence lifetimes and intensities were also discussed. The samples exhibited a higher quenching concentration of Eu3+, and luminescence lifetimes of nanoparticles are related to annealing temperature of samples and the doping concentration of Eu3+ ions.

Silica-coated Y2O3 : Eu nanoparticles and their luminescence properties

Crystalline Y2O3:Eu is of paramount significance in rare earth materials and research on luminescence spectra. In this work, the nanocrystalline Y2O3:Eu was coated with silica by a facile solid state reaction method at room temperature. The transmission electron microscope (TEM) photographs showed that the prepared Y2O3:Eu particle is polycrystalline with the size of 20 nm, the size of silica-coated particle is about 25 nm. The XPS spectra indicated that the silica layer is likely to interact with Y2O3:Eu by a Si-O-Y chemical bond. The luminescence spectra showed that the intensity of ground samples is lower than that of unground ones, the intensity of silica-coated phosphors is higher than that of the ground samples, while almost the same as that of the unground ones. Therefore, the silica coating decreases the surface defects of nanoparticles of the nanocrystalline Y2O3:Eu, thus increasing their luminescent intensity.

Morphological control and luminescent properties of CeF3 nanocrystals

The nanocrystals of CeF3 with the hexagonal structure and different morphologies such as the disk, the rod, and the dot have been successfully synthesized via a mild ultrasound assisted route from an aqueous solution of cerium nitrate and different fluorine sources (KBF4, NaF, NH4F). The use of different fluorine sources has a remarkable effect on the morphology of the final product. The luminescence and UV-vis absorption properties of CeF3 nanocrystals with different morphologies have been investigated. Compared with other shape nanocrystals, the luminescence intensity of the disklike nanocrystals is obviously enhanced. It is suggested that the function-improved materials could be obtained by tailoring the shape of the CeF3 nanocrystals.

Sonochemical synthesis and luminescence properties of single-crystalline BaF2:Eu3+ nanospheres

BaF2 nanocrystals doped with 5.0 mol% Eu3+ has been successfully synthesized via a facile, quick and efficient ultrasonic solution route employing the reactions between Ba(NO3)(2), Eu(NO3)(3) and KBF4 under ambient conditions. The product was characterized via X-ray powder diffraction (XRD), scanning electron micrographs (SEM), transmission electron microscopy (TEM), high-resolution transmission electron micrographs (HRTEM), selected area electron diffraction (SAED) and photoluminescence (PL) spectra. The ultrasonic irradiation has a strong effect on the morphology of the BaF2:Eu3+ particles. The caddice-sphere-like particles with an average diameter of 250 nm could be obtained with ultrasonic irradiation, whereas only olive-like particles were produced without ultrasonic irradiation. The results of XRD indicate that the obtained BaF2:Eu3+ nanospheres crystallized well with a cubic structure. The PL spectrum shows that the BaF2:Eu3+ nanospheres has the characteristic emission of Eu3+ D-5(0)-F-7(J) (J = 1-4) transitions, with the magnetic dipole D-5(0)-F-7(1) allowed transition (590 nm) being the most prominent emission line.

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.

White electroluminescence from a single polymer system: Improved performance by means of enhanced efficiency and red-shifted luminescence of the blue-light-emitting species

High-efficiency white electrolurninescence from a single polymer is achieved by enhancing the electroluminescence efficiency and effecting a red-shift in the emission spectrum of the blue emissive species. A single-layer device of the resultant polymer exhibits a higher luminous efficiency than the nonmodified species (12.8 cd A(-1), see figure) and an external quantum efficiency of 5.4 % with CIE coordinates of (0.31,0.36), exemplifying the success of the reported methodology.

Synthesis, structure and luminescence properties of zinc (II) complexes with terpyridine derivatives as ligands

Five zinc (II) complexes (1-5) with 4 '-phenyl-2,2 ':6 ',2 ''-terpyridine (ptpy) derivatives as ligands have been synthesized and fully characterized. The para-position of phenyl in ptpy is substituted by the group (R), i.e. tert-butyl (t-Bu), hexyloxy (OHex), carbazole-9-yl (Cz), naphthalen-1-yl-phenyl-amine-N-yl (NPA) and diphenyl amine-N-yl (DPA), with different electron-donating ability. With increasing donor ability of the R, the emission color of the complexes in film was modulated from violet (392 nm) to reddish orange (604 nm). The photoexcited luminescence exhibits significant solvatochromism because the emission of the complexes involves the intra-ligand charge transfer (ILCT) excited state. The electrochemical investigations show that the complexes with stronger electro-donating substituent have lower oxidation potential and then higher HOMO level. The electroluminescence (EL) properties of these zinc (II) complexes were studied with the device structure of ITO/PEDOT/Zn (II) complex: PBD:PMMA/BCP/AlQ/ LiF/Al. Complexes 3, 4 and 5 exhibit EL wavelength at 552, 600 and 609 nm with maximum current efficiency of 5.28, 2.83 and 2.00 cd/A, respectively.

Electrogenerated chemi luminescence from Ru(BPY)(3)(2+) ion-exchanged in carbon nanotube/perfluorosulfonated ionomer composite films

The electrochemistry and electrogenerated chemiluminescence (ECL) of ruthenium(II) tris(bipyridine) (Ru(bpy)(3)(2+)) ion-exchanged in carbon nanotube (CNT)/Nafion composite films were investigated with tripropylamine (TPA) as a coreactant at a glassy carbon (GC) electrode. The major goal of this work was to investigate and develop new materials and immobilization approaches for the fabrication of ECL-based sensors with improved sensitivity, reactivity, and long-term stability. Ru(bpy)(3)(2+) could be strongly incorporated into Nafion film, but the rate of charge transfer was relative slow and its stability was also problematic. The interfusion of CNT in Nafion resulted in a high peak current of Ru(bpy)(3)(2+) and high ECL intensity. The results indicated that the composite film had more open structures and a larger surface area allowing faster diffusion of Ru(bpy)(3)(2+) and that the CNT could adsorb Ru(bpy)(3)(2+) and also acted as conducting pathways to connect Ru(bpy)(3)(2+) sites to the electrode. In the present work, the sensitivity of the ECL system at the CNT/Nafion film-modified electrodes was more than 2 orders of magnitude higher than that observed at a silica/Nafion composite film-modified electrode and 3 orders of magnitude higher than that at pure Nafion films.