Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2016-03-29T14:51:59Z No. of bitstreams: 1 arquivototal.pdf: 2889280 bytes, checksum: 9c7ca34cb774b831c8a33f50c09aee7f (MD5) / Made available in DSpace on 2016-03-29T14:51:59Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2889280 bytes, checksum: 9c7ca34cb774b831c8a33f50c09aee7f (MD5) Previous issue date: 2015-02-26 / Nanomedicine is the use of nanomaterials in developing new therapeutic and diagnostic procedures. However, despite the advantages and different applications of nanoparticles, they also have potential toxic effects that should be properly assessed before use. Metal oxides and, in particular, metal oxide nanoparticles have many applications. Among them, cerium oxide nanoparticles and zinc oxide have shown different pharmacological activities, both alone, and in combination with each other. Cancer is a complex genetic disease which is a major public health problem worldwide, one of the leading causes of death in Brazil. This study aimed to evaluate the toxicity and antitumor activity in vivo of cerium oxide nanoparticles and zinc oxide association (NCZ). Initially it was evaluated the acute preclinical toxicity orally with estimated NCZ LD50 above 2000 mg/kg, therefore, the sample is considered to have low toxicity in our experimental conditions. Subsequently it was performed the evaluation of repeated doses toxicity study (28 days) of NCZ by oral route. The treatment resulted in a significant decrease in the consumption of water and feed, significant increase in enzyme activity of ALT and AST, significant decrease of urea, significant increase in the total white blood cell count, significant decrease in thymus index, significantly increased of ambulation and a decrease in time of self-cleaning and withdrawals. The study of acute toxicity by intraperitoneal route, the LD50 of NCZ was estimated at about 300 mg/kg enabling the choice of doses to be used in the study of antitumor activity. NCZ showed significant antitumor activity in Ehrlich ascites carcinoma model (EAC) at doses of 10, 20 and 40 mg/kg, considering the mass, tumor volume and total cell parameters. In the investigation of its mechanism of action was observed that NCZ increased the percentage of cells in sub-G1 phase, decreased microvessel peritoneal vascular, as well promoted an increased in the concentration of IL-1, IL-10, TNF- and IFN-. It was also evaluated the toxicity of NCZ in animals with EAC submitted to antitumor treatment for nine days. It was observed a significant decrease in feed intake, significant increase in ALT activity, significant decrease in serum urea concentration, significant increase in serum creatinine and significant increase in the mean corpuscular hemoglobin. According to the results, we can infer that NCZ has low toxicity and significant antitumor activity in vivo with mechanism of action probably related to interference with the progression of the cell cycle, inducing apoptosis, increased immune response and antiangiogenic action. / A nanomedicina consiste na utilização de nanomateriais no desenvolvimento de novas modalidades terapêuticas e de diagnóstico. Todavia, apesar das vantagens e diferentes aplicações das nanopartículas, estas também possuem potenciais efeitos tóxicos que devem ser devidamente avaliados antes de sua utilização. Óxidos de metais e, em especial, nanopartículas de óxido de metais possuem várias aplicações. Dentre eles o óxido de zinco e nanopartículas de óxido de cério já demonstraram diversas atividades farmacológicas tanto de forma isolada, quanto em associação entre si. Especialmente para nanopartículas de óxido de cério, vários estudos mostram seu potencial antitumoral. O câncer é uma doença genética complexa que constitui um importante problema de saúde pública em todo mundo, sendo uma das principais causas de morte no Brasil. Esse trabalho teve como objetivo avaliar a toxicidade e atividade antitumoral in vivo de nanopartículas de óxido de cério associadas ao óxido de zinco (NCZ). Inicialmente foi avaliada a toxicidade pré-clínica aguda, por via oral, com estimativa de DL50 para NCZ acima de 2000 mg/kg sendo, portanto, a amostra considerada de baixa toxicidade nas condições experimentais avaliadas. Em seguida foi realizada a avaliação da toxicidade pré-clínica de doses repetidas (28 dias) de NCZ, por via oral. O tratamento resultou em diminuição significativa no consumo de água e ração, ureia, índice do timo e tempo de auto-limpeza e levantamentos, assim como resultou em um aumento significativo na atividade enzimática de ALT e AST, contagem total de leucócitos e ambulação. No estudo de toxicidade aguda por via intraperitoneal de NCZ a DL50 foi estimada em torno de 300 mg/kg possibilitando a escolha das doses a serem utilizadas no estudo de atividade antitumoral. NCZ apresentou significante atividade antitumoral em modelo de Carcinoma Ascítico de Ehrlich (CAE) nas doses de 10, 20 e 40 mg/kg, considerando os parâmetros massa e volume tumoral, bem como total celular. Na investigação de seu mecanismo de ação foi observado que NCZ aumentou a percentagem de células na fase sub-G1, reduziu a microdensidade vascular peritoneal, bem como aumentou a concentração de IL-1, IL-10, TNF- e IFN-. Foi avaliada ainda, a toxicidade de NCZ nos animais com CAE submetidos ao tratamento antitumoral de nove dias, sendo observada uma diminuição significativa no consumo de ração e na concentração sérica de ureia, assim como resultou em aumento significativo na atividade da ALT, concentração sérica de creatinina e hemoglobina corpuscular média. De acordo com os resultados obtidos, é possível inferir que NCZ apresenta baixa toxicidade e significante atividade antitumoral in vivo com mecanismo de ação provavelmente relacionado a uma interferência na progressão do ciclo celular com indução de apoptose, aumento da resposta imune antitumoral e ação antiangiogênica.

Made available in DSpace on 2014-10-09T12:41:53Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:30Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:11/05408-2

Made available in DSpace on 2015-05-14T13:21:20Z (GMT). No. of bitstreams: 1 ArquivoTotal.pdf: 4059919 bytes, checksum: 060bb659754e4494028dcb4bf65722e1 (MD5) Previous issue date: 2013-06-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The cerium oxide(IV) (CeO2) has wide application in several areas such as environmental, catalytic, microbiological and its efficiency depends on the morphology and particle size. In this study, they were synthesized by hydrothermal method assisted by microwave under NaOH and NH4OH mineralizers added to a Cerium sulfate tetrahydrate (Ce(SO4)2.4H2O) aqueous solution, at 150°C for 1, 5, 15, 30 and 60 minutes,with and without surfactant that was used as a template for crystal growth. The thermal stability was studied by thermogravimetry (TG). The structural and morphological properties were evaluated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), BET method, infrared spectroscopy (IR), UV-visible spectroscopy (UV-vis) and Raman spectroscopy, Resazurin tests, absorbance, fluorescence and diffusion wells. All samples show XRD peaks corresponding to the plane (1 1 1), (2 0 0), (0 2 2), (3 1 1), (2 2 2) and (4 0 0) of a cube face-centered, fluorite, structure assigned to CeO2 in accordance with the standard JCPDS 34-0394. It is clearly seen that the reflection peaks are broad, indicating that the crystal size is small and should be in nanoscalerange. In addition, data give an indication of the influence of the template and the method for obtaining this nanostructured material. In the Raman spectrum, strong peak around 471 cm-1 was detected, which is the only active mode, of first order, assigned to symmetric O-Ce-O stretching. In the infrared spectra bands between 700 and 400 cm-1 were observed, being related to metal-oxygen vibration.Infrared spectra showed a vibration band between 700 and 500 cm-1related to metal-oxygen vibration (Ce-O). Bands assigned to hydroxyls groups (1100 cm-1) and carbonates (1530, 1050 and 850 cm-1) were also observed independently of the presence of the PEG 200. Bands assigned to water (1629 cm-1) were also present.The surface areas of the synthesized materials were approximately 200 g.m2 and particulates sizes around 5nm. FEG-SEM micrographs of samples obtained with and without template showed particles of different sizes, forming different clusters. Microbiological tests showed, at a concentration of 10% cerium oxide nanostructured in oxide zinc dental application, minimum inhibitory concentration value of 0,22 μg/mL-1.The results showed the influence of the template on the morphology of ceria nanoparticles, obtained by microwave-assisted hydrothermal method, its potential application as an antimicrobial agent against Streptococcus mutans bacteria, the most important microorganism related to dental caries ethiology, dental drug application. / O óxido de cério(IV) (CeO2) tem potencial aplicação nas áreas ambientais, catalíticas, microbiológicas e a eficiência de suas nanopartículas dependem da morfologia e de suas dimensões. Nesse estudo, elas foram sintetizadas pelo método hidrotermal assistido por micro-ondas com NaOH e NH4OH, como agentes mineralizantes, adicionado a uma solução aquosa de sulfato de cério (Ce (SO4) 2.4H2O) a 150°C durante 1, 5, 15, 30 , e 60 minutos, com e sem surfactante, que foi utilizado como matriz para o crescimento de cristais. A estabilidade térmica foi estudada por termogravimetria (TG). As propriedades estruturais, morfológicas e microbiológicas foram avaliadas por difração de raios-X (XRD), microscopia eletrônica de varredura de alta resolução (FEG-SEM), microscopia eletrônica de transmissão (TEM), método de BET, espectroscopia de infravermelho (IR), espectroscopia de UV-visível (UV-vis), espectroscopia Raman, prova de resazurina, absorbância, fluorescência e difusão de poços.Todas as amostras de DRX mostraram picos que correspondem aos planos (1 1 1), (2 0 0), (0 2 2), (3 1 1), (2 2 2) e (4 0 0) de um cubo de face centrada, fluorita, atribuída a estrutura de CeO2, de acordo com a norma JCPDS 34-0394. Picos largos de reflexão foram claramente visualizados, indicando que o tamanho do cristal é pequeno e deve estar na dimensão nanoescalar, dando uma indicação da influência do template e do método de obtenção deste material nanoestruturado. No espectro de Raman, forte pico em torno de 471 cm-1 foi detectado, o qual é atribuído ao alongamento O-Ce-O. Espectros de infravermelho mostraram uma banda de vibração entre 700 e 500 cm-1, relacionada com a vibração metal-oxigênio (Ce-O). Bandas atribuídas a grupos hidroxilas (1100 cm-1) e carbonatos (1530, 1320, 1050 e 850 cm-1), independentemente da presença do PEG 200, foram também observadas, além de bandas atribuídas a água (1629cm-1).Suas áreas superficiais foram de, aproximadamente, 200 g/m2 com tamanhos de partículas em torno 5nm. As Micrografias , com e sem template,mostraram diferentes tamanhos e formas de aglomerados. Os testes microbiológicos mostraram, para concentração de 10% de óxido de cério (IV) nanométrico em óxido de zinco com aplicação odontológica, uma concentração mínima inibitória de 0,22 μg/mL-1 .Os resultados mostraram a influência do template sobre a morfologia das nanopartículas de óxido de cério (IV), obtidas pelo método hidrotermal de micro-ondas e seu potencial como agente antimicrobiano contra a bactéria Streptococcus mutans, o principal microorganismo da etiologia da cárie dentária, em fámacos de aplicação odontológica.

This doctoral thesis concerns the preparation of porous cerium oxide/carbon bilayers on silicon substrates. In this regard, carbonaceous films in the form of amorphous carbon (a-C) and nitrogenated amorphous carbon (CNx) are considered. The influence of various process parameters of the cerium oxide deposition on the morphology of the final cerium oxide/carbon bilayer is investigated. A correlation could be found between the morphol- ogy of the bilayer and the stoichiometry of the cerium oxide film determined by means of XPS. Furthermore, a study regarding the chemical composition of the used carbonaceous films by means of various spectroscopic techniques is presented. It was found that the chemical composition of the carbonaceous films strongly depends on the deposition con- ditions of these films and influences the behaviour of these films during oxygen plasma treatment and cerium oxide deposition, respectively. 1

Title: Role of surface defects in ceria-based catalysis Author: Andrii Tovt Department: Department of Surface and Plasma Science Supervisor of the doctoral thesis: doc. Mgr. Josef Mysliveček Ph.D., Department of Surface and Plasma Science Abstract: This work concentrates on the analysis of fundamental physicochemical properties of Pt-CeOx, single-atom Pt1 /CeOx, and inverse CeOx/Cu(111) catalysts. Preparation method for stabilized atomically-dispersed Pt2+ ions on ceria was developed and adsorption sites for Pt ions were thoroughly studied using advanced surface science techniques supported by theoretical methods. The mechanism of Pt2+ stabilization on ceria steps was revealed and the step capacity towards Pt2+ ions was estimated. Also, the preparation method for well-ordered cerium oxide ultrathin films with different stoichiometry and ordering of surface oxygen vacancies was developed, and the Ceria/Cu(111) interaction was investigated. Key words: heterogeneous catalysis, model systems, single-atom catalysis, platinum ions, cerium oxide.

There is a consistent need in many industries, especially oil and gas, to develop coatings which have higher corrosion resistance and better hardness to extend the lifetime of equipment when it is exposed to hostile environments. Electrodeposition has been a favorable method in the synthesis of metal coatings because of its low cost, convenience, ability to work at low temperatures, and ability to control surface morphology and structure. The inclusion of ceramic nanoparticles in metal matrix composites has previously been investigated as a technique to not only increase the corrosion resistance of the native metal but also to improve the hardness and mechanical properties. Cerium oxide nanoparticles were modified through the grafting of organic groups with increasing hydrophobicity for use in nickel coatings on stainless steel to further improve the corrosion properties while maintaining the hardness of the nanocomposite coatings. The process of modifying the cerium oxide nanoparticles involved the use of aryl diazonium salts and resulted in multilayers forming on the surface of the nanoparticles. Praseodymium oxide nanoparticles were also investigated as additives to nickel coatings, since praseodymium oxide has not yet been studied as a possible corrosion protection enhancement in coatings. These coatings were evaluated for composition and corrosion using many different types of instrumental and electrochemical techniques. With the addition of both the modified cerium oxide nanoparticles and the praseodymium oxide nanoparticles into nickel coatings, an increase in coating hardness and corrosion resistance was observed over pure nickel, resulting in an improvement of the lifetime of these coatings.

No description available.

Cerium oxide (ceria)-based materials in the nanoscale regime are of significant fundamental and technological interest. Nanoceria in pure and doped forms has current and potential use in solid oxide fuel cells, catalysis, UV- screening, chemical mechanical planarization, oxygen sensors, and bio-medical applications. The characteristic feature of Ce to switch between the +3 and + 4 oxidation states renders oxygen buffering capability to ceria. The ease of this transformation was expected to be enhanced in the nanoceria. In most the practical scenarios, it is necessary to have a stable suspension of ceria nanoparticles (CNPs) over longer periods of time. However, the existing literature is confined to short term studies pertaining to synthesis and property evaluation. Having understood the need for a comprehensive understanding of the CNP suspensions, this dissertation is primarily aimed at understanding the behavior of CNPs in various chemical and physical environments. We have synthesized CNPs in the absence of any surfactants at room temperature and studied the aging characteristics. After gaining some understanding about the behavior of this functional oxide, the synthesis environment and aging temperature were varied, and their affects were carefully analyzed using various materials analysis techniques such as high resolution transmission electron microscopy (HRTEM), UV-Visible spectroscopy (UV-Vis), and X-ray photoelectron spectroscopy (XPS). When the CNPs were aged at room temperature in as-synthesized condition, they were observed to spontaneously assemble and evolve as fractal superoctahedral structures. The reasons for this unique polycrystalline morphology were attributed to the symmetry driven assembly of the individual truncated octahedral and octahedral seed of the ceria. HRTEM and Fast Fourier Transform (FFT) analyses were used to explain the agglomeration behavior and evolution of the octahedral morphology. Some of the observations were supported by molecular dynamic simulations. Poly (ethylene glycol) (PEG) and ethylene glycol (EG) were used to control the kinetics of this morphology evolution. The ability to control the agglomeration of CNPs in these media stems from the lower dielectric constant and an increased viscosity of the EG and PEG based solvents. CNPs when synthesized and aged in frozen conditions, i.e. in ice, were found to form one dimensional, high aspect ratio structures. A careful analysis has provided some evidence that the CNPs use the porous channels in ice as a template and undergo oriented attachment to form nanorods. When the aging treatment was done near freezing temperature in solution, the nanorods were not observed, confirming the role of channels in ice. When synthesized in aqueous media such as DI water, PEG and EG; CNPs were observed to exhibit a reversible oxidation state switching between +3 and +4. Band gap values were computed from the optical absorption data. The changes in the band gap values observed were attributed to the changes in the oxidation state of CNPs as opposed to the quantum confinement effects, as expected in other nanoparticle systems. The work presented in this dissertation demonstrates, with evidence, that in order to obtain a comprehensive understanding of the properties of nanoscale materials it is of paramount importance to monitor their behavior over relatively longer periods of time under various ambient environments. While the solution based techniques offer a versatility and low cost route to study the fundamental properties of nanomaterials, they suffer some inherent problems such as precursor contamination and uncontrolled chemical reactions. Especially when analyzing the behavior of ceria-based materials for applications like solid oxide fuel cells, a great control in the density and crystalline quality are desired. In order to achieve this, as a first step pure ceria thin films were synthesized using oxygen plasma assisted molecular beam epitaxy (OPA-MBE). The ceria films were analyzed using various in situ and ex situ techniques to study the crystal structure, growth mode and epitaxial quality of the films. It was observed that the epitaxial orientation of the ceria films could be tuned by varying the deposition rate. When the films were grown at low deposition rate (< 8 Å/min) ceria films with epitaxial (200) orientation were observed where as the films grown at high deposition rates (up to 30 Å/min) showed (111) orientation. Theoretical simulations were used to confirm some of the experimental facts observed in both nanoparticles and thin films.

Die vorliegende Habilitationsschrift bespricht aktuelle Ergebnisse zur Struktur und Reaktivität von Übergangsmetalloxidoberflächen. Es werden eingangs Grundlagen zur Berechnung von Eigenschaften von Oberflächen mittels Dichtefunktionaltheorie vorgestellt. Des Weiteren werden anhand von drei untersuchten Oxiden, nämlich dem Vanadium(III)-oxid, dem Cer(IV)-oxid, und dem Eisen(II,III)-oxid, der aktuelle Forschungsstand im Hinblick auf Oberflächenstruktur und Reaktivität von Phasengrenzen, wie z.B. der Phasengrenze zwischen Vanadium(V)-oxid und Cer(IV)-oxid und der Phasengrenze zwischen Wasser und Eisen(II,III)-oxid dargelegt. / The present habilitation thesis discusses results on structure and reactivity of transition metal oxide surfaces obtained using state-of-the-art density functional theory methods. First, fundamental issues of density functional theory are presented. Furthermore, the current state in research with respect to surface structure on one hand and reactivities of interfaces between different oxides like vanadium(III) and cerium(IV) oxide or water and iron(II,III) oxide on the other hand are developed.

<p dir="ltr">The primary goal of this work is to gain a fundamental understanding on how growth conditions affect the morphology and crystallography orientation of CeO₂/Au vertically aligned nanocomposite (VAN) thin films. Focus has been placed on how the changes in morphology and crystallography translate to tunable optical properties. The morphological effects have been observed and analyzed via two main approaches: the change in morphology was observed at multiple points along the film thickness, and the morphology at the film/substrate interface has been analyzed with respect to total film thickness. The changes in Au crystallography orientations have been observed by measuring peak shift in XRD patterns and determining the resulting in- and out-of-plane strain. To observe additional effects of this morphology change, optical measurements have been taken for films at the bottom, middle, and top of the thickness range. Strong trends in transmittance, plasmonic absorption peak shifts and hyperbolic permittivity behavior are correlated with the film thickness. This tunability of optical properties likely arises from changes in both Au pillar phase morphology and crystal orientation. These findings demonstrate that changing film thickness may be a desirable method to easily tune the morphology and optical properties of VAN thin films.</p>