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Europium-doped lanthanide oxide RE(2)O(3):Eu(3+) (RE = Y or Gd) luminescent beads, with a spherical shape and a diameter of 150 ± 15 nm, have been modified by reaction with 3-aminopropyltriethoxysilane (APTES), in order to introduce reactive amine groups at their surfaces. The direct silanation has resulted in the formation of a nanometric layer at the surface of the beads, with an optimum grafting rate of 0.055 ± 0.005 mol APTES/mol RE(2)O(3). Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies confirmed the condensation of an organosilane layer, made of cross-linked -O-Si-O-Si- and of groups -O-Si-R (with R = (CH(2))(3)NH(2) or O-Et). Titration of the accessible amine groups has been performed by simultaneously measuring the luminescence of grafted fluorescein isothiocyanate and that of core particles: there are about 2.3 × 10(4) (2.8 × 10(4)) -NH(2) per Y(2)O(3):Eu(3+) (Gd(2)O(3):Eu(3+)) bead. The isoelectronic point was shifted by one pH unit after APTES modification. The surface modification by APTES at least preserved (for Gd(2)O(3):Eu(3+)) or improved (for Y(2)O(3):Eu(3+)) the red emission of the beads., (© 2012 American Chemical Society)

Abstract: The spray-pyrolysis (SP) synthesis technique has been employed to obtain SiO2:Eu3+ and γ-AlOOH:Eu3+. It was possible to obtain sub-micrometric spherical particles of SiO2 with luminescent Eu3+ ions bonded to the silica surface or embedded in amorphous silica beads, by controlling the synthesis and annealing process. Boehmite γ-AlOOH doped with Eu3+ nanoparticles were synthesized by SP at moderate temperature (200°C) with Eu3+ ions bonded to the surface hydroxyls of the boehmite nanocrystals. Luminescent nano-composites were obtained by controlled reaction of γ-AlOOH:Eu3+ nanocrystals with ASN (asparagine). In these nano-composites, the Eu3+ are held at the surface of the boehmite nanocrystals and partially shielded from interactions with additional luminescence quenchers (hydroxyl groups, water molecules). [Copyright &y& Elsevier]

A new support for traditional radiotherapy based on the UV emission from Pr 3+ doped LaPO 4 nanoparticles is proposed. This system was obtained by spray pyrolysis methodology. X-ray diffraction (XRD) analysis showed that the synthesized particles exhibited a lanthanum orthophosphate structure. Transmission electron microscopy (TEM) revealed that the ultrasound treatment successfully converted the microparticles into nanoparticles. The surfaces were chemically modified with amino acid (asparagine and aminocaproic acid). XEOL measurements evidenced a broad band in the UVC range, which could allow for application of the system as UVC emitter in internal phototherapy. [ABSTRACT FROM AUTHOR]