Navegando por Palavras-chave "Europium"

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    Crystal growth and photoluminescence of europium-doped strontium titanate prepared by a microwave hydrothermal method
    (Elsevier B.V., 2015-04-01) Goncalves, R. F. [UNIFESP]; Moura, A. P.; Godinho, M. J.; Longo, E.; Machado, M. A. C.; Castro, D. A. de; Siu Li, M.; Marques, A. P. A. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); UFG Univ Fed Goais; LIEC IQ Univ Estadual Paulista; Universidade de São Paulo (USP); Universidade Federal do Pará (UFPA)
    This article reports that europium-doped strontium titanate (SrTiO3:Eu3+) was successfully synthesized using a co-precipitation method at room temperature with processing in a microwave-hydrothermal system at 140 degrees C for 30 min. Phase composition and structure were examined using X-Ray Diffraction, and Fourier-Transform Raman spectroscopy, revealing a cubic structure with a Pm3m space group. the optical properties were investigated by ultraviolet-visible absorption and photoluminescence, which showed that red emissions originate from Eu3+ transitions. Field emission scanning electron microscopy revealed spherical-like Eu3+ doped SrTiO3 nanoparticles. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
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    Early Diagnosis of Prostate Cancer by Citrate Determination in Urine with Europium-Oxytetracycline Complex
    (Soc Applied Spectroscopy, 2012-08-01) Silva, Flavia R. O. [UNIFESP]; Nabeshima, Camila Tiemi [UNIFESP]; Bellini, Maria H.; Courrol, Lilia C. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); IPEN CNEN SP
    Normal prostate tissue contains high levels of citrate. in the presence of prostate cancer, the citrate level is diminished. in this paper we show that it is possible to use europium oxytetracycline complex as a citrate fluorescent probe and consequently as a prostate cancer probe. We analyzed normal nude male mice urine and urine from nude male mice in which prostate cancer was induced by intraprostatic inoculation of DU145 cells. the urine samples were collected from the animals at the 7th, 14th, 21st, and 35th days after the surgery procedures. the intensity of europium emission at 615 nm in europium oxytetracycline complex in the presence of citrate increases linearly. the citrate concentrations were determined from a calculated calibration curve. A concentration decrease in malignant prostate urine from the normal (PBS group) urine value from similar to 8.0 mM to similar to 2.4 mM (tumor group at 35th day) was found. the obtained results indicated that europium oxytetracycline provides a significant biomarker for prostate cancer detection with a direct, accurate, noninvasive, and non-enzymatic method for measurement of citrate in biological fluids.
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    Enhancement on the Europium emission band of Europium chlortetracycline complex in the presence of LDL
    (Elsevier B.V., 2010-05-01) Teixeira, Luciane dos Santos; Grasso, Andrea Nastri; Monteiro, Andrea Moreira; Figueiredo Neto, A. M.; Vieira, Nilson Dias; Gidlund, Magnus; Courrol, Lilia Coronato [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); IPEN CNEN; Universidade de São Paulo (USP)
    Low-density lipoprotein (LDL) particles are the major cholesterol-carrying lipoprotein in the human circulation from the liver to peripheral tissues. High levels of LDL-Cholesterol (LDL-C) are known risk factor for the development of coronary artery disease (CAD). the most common approach to determine the LDLC in the clinical laboratory involves the Friedewald formula. However, in certain situations, this approach is inadequate. in this paper we report on the enhancement on the Europium emission band of Europium chlortetracycline complex (CTEu) in the presence of LDL. the emission intensity at 615 nm of the CTEu increases with increasing amounts of LDL. This phenomenon allowed us to propose a method to determine the LDL concentration in a sample composed by an aqueous solution of LDL. With this result we obtained LDL calibration curve, LOD (limit of detection) of 0.49 mg/mL and SD (standard deviation) of 0.003. We observed that CTEu complex provides a wider dynamic concentration-range for LDL determination than that from Eu-tetracycline previously. the averaged emission lifetimes of the CTEu and CTEu with LDL (1.5 mg/mL) complexes were measured as 15 and 46 Its, respectively. Study with some metallic interferents is presented. (C) 2010 Elsevier Inc. All rights reserved.
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    Estudo das propriedade luminescentes de elastômeros PEBA 2533 contendo complexo de Eu(tta)3(H2O)2
    (Universidade Federal de São Paulo, 2020-09-28) Silva, Pamela Corradi da [UNIFESP]; Molina, Celso [UNIFESP]; Camilo, Fernanda Ferraz [UNIFESP]; http://lattes.cnpq.br/6334598937296642; http://lattes.cnpq.br/3819814458216651; http://lattes.cnpq.br/6402679630201857
    Materiais luminescentes, baseados em complexos de -Dicetona de íons terras raras vêm sendo estudados com potenciais aplicações em diversos campos tecnológicos, tais como em camadas emissoras de diodos orgânicos emissores de luz (OLEDS), displays e sensores e amplificadores ópticos. Diversas matrizes vêm sendo estudadas para imobilizar esses complexos a fim de formar filmes auto-suportados com boas propriedades mecânicas para aplicações em dispositivos flexíveis. Visando a obtenção de um material com propriedades mecânicas e luminescentes, o complexo de - Dicetona - Eu(tta)3(H2O)2 foi incorporado em um elastômero comercial denominado PEBAX ® 2533, que é um copolímero em bloco que possui 20 % de unidades rígidas de poliamida (PA) e 80 % de unidades flexíveis de poliéster (PE) 80 %. Os filmes de PEBAX® 2533 contendo diferentes quantidades do complexo Eu(tta)3(H2O)2 foram preparados e caracterizados por espectroscopia vibracional na região do infravermelho - ATR, difratometria de raios x, espectroscopia eletrônica na região do UV-visível e espectroscopia eletrônica de luminescência. Além disso, também foram avaliadas as propriedades térmicas, por termogravimetria e calorimetria exploratória diferencial, e mecânicas por ensaios de tensão-deformação. Os filmes apresentam alta transparência na região do visível e são termicamente estáveis até aproximadamente 200o C. Apresentam também altos tempos de vida do estado excitado com alta intensidade de emissão na região do vermelhoalaranjado e rendimentos quânticos de emissão por volta de 61 %. As propriedades mecânicas com comportamento altamente elástico com deformação acima de 1000% se mantiveram mesmo com a inclusão do complexo. Os elastômeros luminescentes obtidos são promissores e estão sendo testados com potencial aplicação para dispositivos óticos sensores com propriedades mecânico-luminescentes em colaboração com o grupo de materiais luminescentes da Universidade de Aveiro – Portugal.
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    Europium tetracycline biosensor for the determination of cholesterol - art. no. 643017
    (Spie-int Soc Optical Engineering, 2007-01-01) Courrol, Lilia Coronato [UNIFESP]; Silva, Flávia Rodrigues de Oliveira; Samad, Ricardo Elgul; Mansano, Ronaldo Domingues; Vieira, Nilson Dias; VoDinh, T.; Grundfest, W. S.; Benaron, D. A.; Cohn, G. E.; Raghavachari, R.; Universidade Federal de São Paulo (UNIFESP)
    Development of cholesterol biosensors is of great importance in clinical analysis because the concentration of cholesterol in blood is a fundamental parameter for the prevention and diagnosis of a number of clinical disorders such as heart disease, hypertension and arteriosclerosis. in general, determination of cholesterol is based on spectrophotometry; but this method involves complicated procedures and the cost is high because expensive enzyme must be used in each assay.We report here the observation, for the first time, of the enhancement of Europium-Tetracycline complex emission in cholesterol solutions. This enhancement was initially observed with the addition of the enzyme cholesterol oxidase, which produces H2O2, the agent driver of the Europium tetracycline complex, to the solution. However, it was found that the enzyme is not needed to enhance the luminescence. A calibration curve was determined, resulting in an easy-handling immobilization method with a cheap stable material. This method shows that the complex can be used as a sensor to determine cholesterol in biological systems with good selectivity, fast response, miniature size, and reproducible results.
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    Evaluation of europium-doped HA/beta-TCP ratio fluorescence in biphasic calcium phosphate nanocomposites controlled by the pH value during the synthesis
    (Elsevier Science Bv, 2016) Silva, Flavia R. O.; Lima, Nelson B.; Guilhen, Sabine N.; Courrol, Lilia Coronato [UNIFESP]; Bressiani, Ana Helena A.
    Europium-doped hydroxyapatite (HA), beta-tricalcium phosphate (beta-TCP) and biphasic phosphate nanopowders were synthesized by co-precipitation method and their crystal structures and fluorescence properties were investigated depending on the pH of the starting solution. In the range of pH 6-10, HA and beta-TCP phases coexist The beta-TCP proportion increased as the pH of the solution decreased, while HA yields decreased. At pH below 6, monophasic beta-TCP powder was obtained after thermal treatment. In particular, HA and beta-TCP can be used as luminescent materials when activated by Eu3+ ions in substitution of Ca2+ ions. Herein, the Eu3+ ions doped HA and beta-TCP phase composition were analyzed in order to investigate the fluorescence emission of the HA, beta-TCP and biphasic compounds. Eu-doped HA exhibited a red-orange emission at 575 nm with several minor peaks at 610-640 nm, while Eu-doped beta-TCP had an unexpected strong red emission at 610-620 nm and a secondary band at 590-600 nm. In fact, the Eu:beta-TCP integrated emission area is almost 20-fold higher than Eu:HA for the same europium ion concentration. These results demonstrate the potential of Eu:beta-TCP as biomarker for medical applications, as drug release and targeting based on their luminescent properties. (C) 2016 Elsevier B.V. All rights reserved.
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    Investigation of the Europium Emission Spectra of the Europium-Oxytetracycline Complex in the Presence of Human Low-Density Lipoproteins
    (Springer, 2011-05-01) Santos Teixeira, Luciane dos; Grasso, Andrea Nastri; Monteiro, Andrea Moreira; Figueiredo Neto, Antonio M.; Vieira, Nilson Dias; Gidlund, Magnus; Steffens, Juliana; Courrol, Lilia Coronato [UNIFESP]; Universidade Federal de São Paulo (UNIFESP); IPEN CNEN SP; Universidade de São Paulo (USP)
    Low-Density Lipoprotein (LDL), often known as bad cholesterol is one of the responsible to increase the risk of coronary arterial diseases. for this reason, the cholesterol present in the LDL particle has become one of the main parameters to be quantified in routine clinical diagnosis. A number of tools are available to assess LDL particles and estimate the cholesterol concentration in the blood. the most common methods to quantify the LDL in the plasma are the density gradient ultracentrifugation and nuclear magnetic resonance (NMR). However, these techniques require special equipments and can take a long time to provide the results. in this paper, we report on the increase of the Europium emission in Europium-oxytetracycline complex aqueous solutions in the presence of LDL. This increase is proportional to the LDL concentration in the solution. This phenomenum can be used to develop a method to quantify the number of LDL particles in a sample. A comparison between the performances of the oxytetracycline and the tetracycline in the complexes is also made.
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    Silk fibroin-antigenic peptides-YVO4:Eu3+ nanostructured thin films as sensors for hepatitis C
    (Elsevier Science Bv, 2016) Lima, Lais R.; Moraes, Marli L. [UNIFESP]; Nigoghossian, Karina; Peres, Maristela F. S.; Ribeiro, Sidney J. L.
    Nanostructured films prepared by Layer-by-Layer technique and containing silk fibroin, antigenic peptide NS5A-1 derived from hepatitis C virus (HCV) NS5A protein and YVO4:Eu3+ luminescent nanoparticles, were utilized in sensing of hepatitis C. Detection system exploits the biorecognition between the antibody anti-HCV and the antigenic peptide NS5A-1 through changes in luminescence properties. Films deposition was monitored by UV-vis Absorption and Fluorescence Spectroscopy measurements at each bilayer deposited. The Eu3+ luminescence properties were evaluated in the presence of anti-HCV for optical detection of specific antibody and anti-HIV used as negative control. Significant changes in luminescence were observed in the presence of anti-HCV concentrations. A new immunosensor platform is proposed for optical detection of hepatitis C. (C) 2015 Elsevier B.V. All rights reserved.
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    Silk fibroin-antigenic peptides-YVO4:Eu3+ nanostructured thin films as sensors for hepatitis C
    (Elsevier Science Bv, 2016) Lima, Lais R.; Moraes, Marli L. [UNIFESP]; Nigoghossian, Karina; Peres, Maristela F. S.; Ribeiro, Sidney J. L.
    Nanostructured films prepared by Layer-by-Layer technique and containing silk fibroin, antigenic peptide NS5A-1 derived from hepatitis C virus (HCV) NS5A protein and YVO4:Eu3+ luminescent nanoparticles, were utilized in sensing of hepatitis C. Detection system exploits the biorecognition between the antibody anti-HCV and the antigenic peptide NS5A-1 through changes in luminescence properties. Films deposition was monitored by UV-vis Absorption and Fluorescence Spectroscopy measurements at each bilayer deposited. The Eu3+ luminescence properties were evaluated in the presence of anti-HCV for optical detection of specific antibody and anti-HIV used as negative control. Significant changes in luminescence were observed in the presence of anti-HCV concentrations. A new immunosensor platform is proposed for optical detection of hepatitis C. (C) 2015 Elsevier B.V. All rights reserved.
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    Síntese de compostos de coordenação com Eu3+, Tb3+, Al3+ e Zn2+ derivados do ácido 2-(4-hidroxiazobenzeno)benzóico
    (Universidade Federal de São Paulo, 2023-10-19) Silva, Vinicius Flores da [UNIFESP]; Bagatin, Izilda Aparecida [UNIFESP]; http://lattes.cnpq.br/1306989214227206; http://lattes.cnpq.br/4277533392074659
    O presente trabalho consiste em desenvolver a síntese, caracterizar e realizar ensaios de luminescência de compostos de coordenação entre Eu3+ , Tb3+, Al3+ e Zn2+ e o ligante orgânico ácido 2-(4-hidroxiazobenzeno)benzóico (HABA). Os compostos de coordenação foram sintetizados através de metodologias simples e reagentes de fácil acessibilidade, como hidróxido de sódio e acetonitrila. Os ensaios de luminescência demonstram a emissão mais intensa dos complexos com lantanídeos em 613 nm (5D0 → 7F2) para európio e 542 nm ( 5D4→7F5) para térbio. Por outro lado, obteve-se a emissão do complexo com alumínio em 605 nm e 623 nm para zinco, devido às transições π→π* do ligante. As metodologias propostas demonstraram-se viáveis e futuramente deseja-se realizar estudos mais aprofundados para investigar a possibilidade de utilizar os complexos sintetizados como OLEDs.
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    Síntese e caracterização da manganita La0,7-xEuxSr0,3MnO3: estudo das propriedades magnéticas, térmicas, estruturais e luminescentes
    (Universidade Federal de São Paulo, 2024-06-03) Araujo, Matheus Mota de (UNIFESP); Molina, Celso [UNIFESP]; Silva, Ricardo Alexandre Galdino da [UNIFESP]; http://lattes.cnpq.br/6350523822780669; http://lattes.cnpq.br/3819814458216651; http://lattes.cnpq.br/4171036556787725
    Manganitas são óxidos de manganês que desempenham um importante papel tecnológico devido às suas propriedades magnetocalóricas e de magnetorresistência colossal. Neste trabalho, as manganitas La0,7Sr0,3MnO3 e La0,4Eu0,3Sr0,3MnO3 foram preparadas por síntese no estado sólido pela mistura dos óxidos de lantânio, manganês, estrôncio e európio. Foi feito um estudo das propriedades luminescentes, estruturais, magnéticas e comportamento frente à aplicação de conformação mecânica uniaxial para formação de pastilhas desta manganita. Foram realizadas caracterizações por espectroscopia vibracional na região do infravermelho com transformada de Fourier (FTIR-ATR), microscopia eletrônica de varredura (MEV), difratometria de raios X (DRX), espectroscopia por dispersão de energias de raios X (EDX), por medidas de magnetização em função do campo aplicado e temperatura, e as luminescentes por espectroscopia eletrônica de fotoluminescência. Os principais resultados mostraram que a magnetização de saturação da manganita reduziu em aproximadamente 50 vezes com a inserção do íon európio na estrutura e a manganita com európio apresentou luminescência quando excitada na banda de transição de carga ligante-metal (TCLM). Além disso, as manganitas foram submetidas a diferentes conformações mecânicas sobre corpos de prova na forma de pastilhas. A magnetização de saturação do material aumentou em torno de 10 vezes após a aplicação dessas conformações mecânicas para a manganita contendo európio na estrutura. Também houve um aumento dos tempos de vida experimentais obtidos (decaimento a partir do estado emissor 5D0). Pequena variação no ambiente local do íon Eu3+ foi observada em função da conformação mecânica aplicada, indicando maior assimetria em seu entorno.