Nanoencapsulation and Characterization of Zidovudine on Poly(L-lactide) and Poly(L-lactide)-Poly(ethylene glycol)-Blend Nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Planar and UV written channel optical waveguides prepared with siloxane poly(oxyethylene)-zirconia organic-inorganic hybrids. Structure and optical properties

Organic-inorganic hybrids were prepared using ureapropyltriethoxysilane, methacryloxypropyltrimethoxysilane and acrylic acid modified zirconium(IV) n-propoxide precursors and were characterized by small angle X-ray scattering, X-ray diffraction and photoluminescence spectroscopy. The results indicate an effective interaction between the zirconium-based nanoparticles and the siliceous nanodomains that induces changes in the hybrids' emission features. Planar waveguides were obtained by spin-coating of the prepared sols on sodalime and silica substrates. Refractive index, thickness, number of propagating modes, and attenuation coefficient were measured at 543.5, 632.8 and 1550 nm by the prism coupling technique. The synergism between the two hybrid precursors resulted in monomode planar waveguides with low losses in the infrared ( from 0.6-1.1 dB cm(-1)) which also support a number of propagating modes in the visible ( losses from 0.4-1.5 dB cm(-1)). Channel waveguides were also obtained by UV photopatterning using amplitude or phase masks and propagating modes were observed at 1550 nm.

Small angle X-ray scattering study of surface modified tin oxide nanoparticles prepared by sol-gel route

The surface properties of SnO2 nanoparticles were modified by grafting ionic (Tiron (R). (OH)(2)C6H2(SO3Na)(2)(H2O)-H-.) or non-ionic (Catechol (R). C6H4-1,2-(OH)(2)) capping Molecules during aqueous sol-gel processing to improve the redispersibility of powdered xerogel. The effect of the amount of grafted organic molecules on the redispersibility of powders in aqueous solution at several basic pH values was Studied. The nanostructural features of the colloidal suspensions were analyzed by small angle X-ray scattering (SAXS) measurements. Irrespective of the nature and amount of grafted molecules, complete redispersion was obtained in aqueous solution at pH = 13. The redispersion at pH = 11 results in a mixture of dispersed primary particles and aggregates. The proportion of well dispersed nanoparticles and aggregates (and their average size) can be tuned by the quantity of grafted ionic molecules.

Microstructural and morphological analysis of pure and Ce-doped tin dioxide nanoparticles

Structural morphological studies in pure and Ce-doped tin dioxide nanoparticles with high stability against particle growth were performed in samples, obtained using the polymeric precursor method and prepared at different annealing temperatures. A Ce-rich surface layer was used to control the particle size and stabilize SnO2 against particle growth. The formation of this segregated layer can contribute to a decreased surface energy, acting in the driving force, or reducing the surface mobility. Only the cassiterite SnO2 phase was observed below 1000 degreesC and a secondary phase (CeO2) was observed for the Ce-doped SnO2 at temperatures higher than 1000 degreesC, when de-mixing process occurs. The evolution of crystallite size, microstrain and morphology of the nanoparticles with annealing temperatures was investigated by X-ray diffraction (XRD), associated to Rietveld refinements, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). (C) 2002 Elsevier B.V. Ltd. All rights reserved.

Metal-Organic Semiconductor Nanostructures for Surface-Enhanced Raman Scattering

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Corrosion protection of fluorzirconate glasses coated by a layer of surface modified tin oxide nanoparticles

The protection efficiency against water corrosion of fluorozirconate glass, ZBLAN, dip-coated by nanocrystalline tin oxide film containing the organic molecule Tiron® was investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The chemical bonding structure of the surface region and morphology were studied before and after two water exposure periods of 5 and 30 min. The results of the analysis for the as-grown sample revealed a SnO1.6 phase containing carbon and sulfur, related to Tiron®, and traces of elements related to ZBLAN (Zr, F, Ba). This fact and the clear evidence of the presence of tin oxifluoride specie (SnOxF y) indicates a diffusion of the glass components into the porous coating. After water exposure, the increase of the oxygen concentration accompanied by a strong increase of Zr, F, Ba and Na content is interpreted as filling of the nanopores of the film by glass compounds. The formation of a compact protective layer is supported by the morphological changes observed by AFM. © 2005 Elsevier B.V. All rights reserved.

Influence of solvent on the morphology and photocatalytic properties of ZnS decorated CeO2 nanoparticles

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Decoration of Ti/TiO2 Nanotubes with Pt Nanoparticles for Enhanced UV-Vis Light Absorption in Photoelectrocatalytic Process

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Organic acids and protein compounds causing the photoluminescence properties of natural rubber membranes and the quenching phenomena from Au nanoparticle incorporation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Characterization of tetraethylene glycol passivated iron nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chitosan nanoparticles loaded the herbicide paraquat: The influence of the aquatic humic substances on the colloidal stability and toxicity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A flexible lab-on-a-chip for the synthesis and magnetic separation of magnetite decorated with gold nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Co-deposition of gold nanoparticles and metalloporphyrin using the langmuir-blodgett (LB) technique for Surface-Enhanced Raman Scattering (SERS)

The synergistic effect produced by metallic nanoparticles when incorporated into different systems empowers a research field that is growing rapidly. In addition, organometallic materials are at the center of intensive research with diverse applications such as light-emitting devices, transistors, solar cells, and sensors. The Langmuir-Blodgett (LB) technique has proven to be suitable to address challenges inherent to organic devices, since the film properties can be tuned at the molecular level. Here we report a strategy to incorporate gold nanoparticles (AuNPs) into the LB film by co-deposition in order to achieve surface-enhanced Raman scattering (SERS) of the zinc(II)-protoporphyrin (IX) dimethyl ester (ZnPPIX-DME). Prior to the LB co-deposition, the properties of the Langmuir monolayer of ZnPPIX-DME at the air-water interface, containing AuNPs in the subphase, are studied through the surface-pressure versus mean molecular area (π-A) isotherms. The ZnPPIX-DME+AuNPs π-A isotherm presented a significant shift to higher molecular area, suggesting an interaction between both ZnPPIX-DME molecules and AuNPs. Those interactions are a key factor allowing the co-deposition of both AuNPs and ZnPPIX-DME molecules onto a solid substrate, thus forming the LB film. SERS of ZnPPIX-DME was successfully attained, ensuring the spatial distribution of the AuNPs. Higher enhancement factors were found at AuNP aggregates, as a result of the intense local electromagnetic field found in the metal nanoparticle aggregates. The main vibrational bands observed in the SERS spectra suggest a physical adsorption of the ZnPPIX-DME onto the surface of AuNPs. The latter is not only in agreement with the interactions pointed out by the π-A isotherms but also suggests that this interaction is kept upon LB film co-deposition.

Stabilization of polyaniline by the incorporation of magnetite nanoparticles

Nanocomposites obtained from the polymerization of aniline in the presence of nanoparticles of magnetite (Fe3O4) have been investigated in previous studies. However, there is a lack of information available on the redox interaction of the nanoparticle/conductive polymer couple and the stability that such an oxide can give to the organic phase. In this work, Fe3O4 nanoparticles were incorporated into a PANi matrix by the in-situ oxidative polymerization method. A combination of X-ray diffraction, Mossbauer spectroscopy, transmission electronic microscopy, UV-visible spectroscopy as well as the cyclic voltammetric and Raman spectroscopy techniques, was used to understand the redox effect that the partially oxidized nanoparticles produced on the polymer. It was found that magnetite greatly stabilised PANi, mainly by enhancing the Leucoemeraldine/Emeraldine redox couple and also by reducing the bipolaronic state. (C) 2011 Elsevier B.V. All rights reserved.

Ni/Pd@MIL-101: Synergistic Catalysis with Cavity-Conform Ni/Pd Nanoparticles

Deutsche Forschungsgemeinschaft [SFB 840]