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Cai, Yanping. "Spin and Orbital Moments and Magnetic Order in Fe3O4 Nanoparticle Assemblies." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/3982.
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Fe3O4 magnetic nanoparticles of 5 to 11 nm in size were prepared by organic methods. Particle size was analyzed by both X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. Zero Field Cooling (ZFC) / Field Cooling (FC) and magnetization loop measurements were recorded by VSM, and they confirmed superparamagnetic behavior in the sample. The blocking temperature is found to be in the range of 30 K ~ 170 K. It has a dependence on the particle size. ZFC / FC curves also indicate the presence of magnetic coupling between particles. X-ray Magnetic Circular Dichroism (XMCD) measurements of these nanoparticles were measured at 80 K and 300 K. By using the sum rules, spin and orbital magnetic moments were calculated from the XMCD signal. The results confirm a quenching orbital moment and a large spin moment. The calculated total magnetic moments are somewhat smaller than in bulk Fe3O4. Also, the spin moment at 80 K was found to be larger than at 300 K. X-ray Resonant Magnetic Scattering (XRMS) measurements at different temperatures, polarizations and fields were carried out. The intensity profile gives information on the interparticle distance between nanoparticles which is consistent with TEM results. A magnetic signal was extracted by calculating the dichoroic term, when the energy is tuned to resonant edges. This magnetic signal is confirmed by comparing the dichroic terms at different conditions.
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Haney, Carl Edwin. "Effects on Iron Nanoparticles on Pseudomonas Aeruginosa Biofilms." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1324058048.
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Coker, Zachary. "Deleterious Synergistic Effects of Concurrent Magnetic Field and Superparamagnetic (Fe3O4) Nanoparticle Exposures on CHO-K1 Cell Line." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc799479/.
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While many investigations have been performed to establish a better understanding of the effects that magnetic fields and nanoparticles have on cells, the fundamental mechanisms behind the interactions are still yet unknown, and investigations on concurrent exposure are quite limited in scope. This study was therefore established to investigate the biological impact of concurrent exposure to magnetic nanoparticles and extremely-low frequency magnetic fields using an in-vitro CHO-K1 cell line model, in an easily reproducible manner to establish grounds for further in-depth mechanistic, proteomic, and genomic studies. Cells were cultured and exposed to 10nm Fe3O4 nanoparticles, and DC or low frequency (0Hz, 50Hz, and 100Hz) 2.0mT magnetic fields produced by a Helmholtz coil pair. The cells were then observed under confocal fluorescence microscopy, and subject to MTT biological assay to determine the synergistic effects of these concurrent exposures. No effects were observed on cell morphology or microtubule network; however, cell viability was observed to decrease more drastically under the combined effects of magnetic field and nanoparticle exposures, as compared to independent exposures alone. It was concluded that no significant difference was observed between the types of magnetic fields, and their effects on the nanoparticle exposed cells, but quite clearly there are deleterious synergistic effects of these concurrent magnetic field and nanoparticle exposure conditions.
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Schäfer, Thaynara Marjô Zanette. "Síntese, caracterização e aplicação de nanopartículas de óxido de ferro (Fe3O4)." Universidade Estadual do Oeste do Paraná, 2017. http://tede.unioeste.br/handle/tede/3266.
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Previous issue date: 2017-11-20<br>The textile industries present a high polluting potential, due to the generation of large volumes of liquid waste, containing high organic load and strong coloration derived from the dyes. These effluents can be treated by physical, chemical and biological processes. Among these processes, the adsorption has been widely studied for the removal of water dyes, due to the lower costs, simplicity of operation and high efficiency. Methylene blue (AM), a dye widely used in the textile industry is responsible for the strong staining in the effluents. Even in small amounts (<5 mg Pt Co / L), just as other textile dyes are very visible and affect the appearance, transparency and solubility of the gases, damaging the environment. A material that has been applied as adsorbent for dye removal in wastewater treatment is the magnetic nanoparticle, because it has high adsorption capacity, low cost and magnetic character. The nanoparticles can be prepared by the electrochemical method, thermal decomposition, hydrothermal synthesis, microemulsion, decomposition-precipitation, coprecipitation, chemical vapor deposition and impregnation. Of the most well-known methods of preparation, the coprecipitation method is the oldest, the simplest, the most efficient, and the one that allows greater production on a large scale. In this work, the coprecipitation method was used to synthesize the iron oxide (Fe3O4) nanoparticle obtained by the stoichiometric mixture of Fe2+ and Fe3+ salts in aqueous medium. This material was characterized and applied in solutions with different concentrations of the methylene blue dye in order to study its adsorption capacity. The same procedure was performed with the nanoparticulate compound (Sigma-Aldrich), in order to compare the adsorption capacity. The nanoparticulate material was characterized by magnetization, X-ray diffraction (XRD), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), ultraviolet/ visible (UV/VIS) spectroscopy, scanning electron microscopy) and optical microscopy (MO). By magnetization it was possible to observe the movement of the dispersed particles in aqueous medium toward the magnetic field of the neodymium magnet, which is a property of the ferromagnetic materials. With the solid samples, the supported weight capacity was tested, whereas for the synthesized compound it was 85, 3 g and for the nanoparticulate compound was 105,3 g, it being possible to explain this difference by packaging the particles. The greater the packing of the particles, the greater the magnetic force exerted. By the study of the effect of the pH and temperature of the medium, it was confirmed that at pH 7 and ambient temperature, the interference of the medium does not occur by the surface charges of the adsorbents and thus favoring the dye adsorption process. By reading the absorbances of the AM solutions, it was possible to calculate the equilibrium concentrations and to determine the amount of dye adsorbed by the nanoparticles. At low concentrations (5,0 x 10-6 mol L-1 to 1,0 x 10-5 mol L-1) a linear behavior is observed due to the presence of monomers already in concentrations higher than 1,0x10-5 mol. L-1 has the alteration of the linear behavior of the adjusted line, characteristic of the formation of aggregate and alteration of the coefficient of molar absorption. Scanning and optical electron microscopy showed that the images presented different forms for the nanoparticulate and nanoparticulate nanoparticles (Sigma-Aldrich), and the nanoparticulate presented reduced size and rounded shape when compared to the synthesized compound. By the diffractograms it was inferred that the synthesized material presented in its composition the magnetite (Fe3O4) and hematite (Fe2O3), the nanoparticulate only the presence of magnetite. Through the FTIR spectra for the nanoparticle samples, the major bands corresponding to the Fe-O and O-H bonds were investigated. By means of the TGA analysis, a loss of 2,31% of mass was observed in the variation of 50 to 150ºC, attributed to the presence of water in the sample. Above 150°C, there was another loss of 1,20% corresponding to the mass of gaseous substances, possibly carbon dioxide (CO2) or oxygen gas (O2).<br>As indústrias têxteis apresentam um elevado potencial poluente, devido à geração de grandes volumes de resíduos líquidos, contendo alta carga orgânica e forte coloração derivada dos corantes. Esses efluentes podem ser tratados por processos físicos, químicos e biológicos. Dentre estes processos, a adsorção vem sendo amplamente estudada para a remoção de corantes de águas, devido os menores custos, simplicidade de operação e alta eficiência. O azul de metileno (AM), um corante amplamente utilizado na indústria têxtil é responsável pela forte coloração nos efluentes. Mesmo em pequena quantidade (< 5 mg Pt Co/L), assim como os demais corantes têxteis são bastante visíveis e afetam a aparência, a transparência e a solubilidade dos gases, prejudicando o meio ambiente. Um material que vem sendo aplicado como adsorvente para a remoção de corante no tratamento de águas residuarias é a nanopartícula magnética, pois possui alta capacidade de adsorção, baixo custo e caráter magnético. As nanopartículas podem ser preparadas pelo método eletroquímico, decomposição térmica, síntese hidrotérmica, microemulsão, decomposição-precipitação, coprecipitação, deposição química a vapor e a impregnação. Dos métodos de preparo mais conhecidos, o método da coprecipitação é o mais antigo, simples, eficiente e o que permite maior produção em larga escala. Neste trabalho, o método da coprecipitação foi utilizado para sintetizar a nanopartícula de óxido de ferro (Fe3O4), obtida pela mistura estequiométrica de sais de Fe2+ e Fe3+ em meio aquoso. Este material foi caracterizado e aplicado em soluções com diferentes concentrações do corante azul de metileno, a fim de, estudar a sua capacidade de adsorção. O mesmo procedimento foi realizado com o composto nanoparticulado (Sigma–Aldrich), com o propósito de comparar a capacidade de adsorção. O material sintetizado e o composto nanoparticulado foram caracterizados por magnetização, difração de raios-X (DRX), análise termogravimétrica (TGA), espectroscopia de infravermelho (FTIR), espectroscopia ultravioleta/visível (UV/VIS), microscopia eletrônica de varredura (MEV) e microscopia óptica (MO). Por magnetização foi possível observar o movimento das partículas dispersas em meio aquoso em direção ao campo magnético do ímã de neodímio, sendo esta uma propriedade dos materiais ferromagnéticos. Com as amostras sólidas, testou-se a capacidade de peso suportado, sendo que para o composto sintetizado foi de 85,3 g e para o composto nanoparticulado foi de 105,3 g, sendo possível explicar esta diferença pelo empacotamento das partículas. Quanto maior o empacotamento das partículas, maior a força magnética exercida. Pelo estudo do efeito do pH e temperatura do meio, confirmou-se que em pH 7 e temperatura ambiente, não ocorre a interferência do meio pelas cargas da superfície dos adsorventes e assim tem-se o favorecimento no processo de adsorção do corante. Por meio da leitura das absorbâncias das soluções de AM, foi possível calcular as concentrações no equilíbrio e determinar a quantidade de corante adsorvido pelas nanopartículas. Em baixas concentrações (5,0x10-6 mol. L-1 a 1,0x10-5 mol. L-1) tem-se um comportamento linear, devido à presença de monômeros, já em concentrações superiores a 1,0x10-5 mol. L-1 tem-se a alteração do comportamento linear da reta ajustada, característica da formação de agregado e alteração do coeficiente de absorção molar. Por microscopia eletrônica de varredura e óptica foi observado que as imagens apresentaram formas diferenciadas para a nanopartícula sintetizada e nanoparticulado (Sigma– Aldrich), sendo que o nanoparticulado apresentou tamanho reduzido e formato arredondado quando comparado ao composto sintetizado. Pelos difratogramas inferiu-se que o material sintetizado apresentou em sua composição a magnetita (Fe3O4) e hematita (Fe2O3), já o nanoparticulado somente a presença de magnetita. Através dos espectros de FTIR para as amostras das nanopartículas, averiguaram-se as principais bandas correspondentes as ligações Fe-O e O-H. Por meio da análise TGA, observou-se uma perda de 2,31% de massa na variação de 50 a 150ºC, atribuído a presença de água na amostra. Acima de 150ºC, houve outra perda de 1,20% correspondente a massa de substâncias gasosas, possivelmente dióxido de carbono (CO2) ou O2 (gás oxigênio).
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Baratli, Yosra. "Etude de la toxicité des nanoparticules d'oxyde de fer (Fe3O4) chez le rat : analyses mitochondriales et du stress oxydant." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAJ023/document.
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L’objectif de notre travail consiste à caractériser des nanoparticules d’oxyde de fer (Fe3O4) et étudier leur toxicité aiguë chez le rat Wistar. Nos résultats ont montré que l’administration orale aiguë des Fe3O4, entraîne une altération dose- et temps-dépendante des paramètres du stress oxydant ainsi qu’une atteinte hépatique. En ce qui concerne l’étude in vitro sur des mitochondries isolées, nos résultats ont montré que ces nanoparticules n’altèrent ni les différents complexes de la chaîne respiratoire mitochondriale ni le couplage mitochondrial, et ceci dans aucun des organes étudiés (cerveau, cœur, poumon, foie et reins) et quelle que soit la concentration utilisée (100, 200, 300 et 500 μg/ml), alors que les mitochondries hépatiques isolées des rats âgés (18 mois), une altération est observée au niveau de tous les complexes de la chaîne respiratoire mitochondriale hépatique ainsi que pour le couplage mitochondrial quelle que soit la concentration utilisée (250, 300 et 350 μg/ml) alors que pour les rats jeunes (3mois) on n’observe aucune altération<br>The objective of our work is to characterize iron oxide nanoparticles (Fe3O4) and study their acute toxicity in Wistar rats. Our results showed that acute oral administration of Fe3O4, results in a dose and time-dependent alteration of oxidative stress parameters as well as liver damage. Regarding the in vitro study on isolated mitochondria, our results showed that these nanoparticles do not adversely affect the various complexes of the mitochondrial respiratory chain or mitochondrial coupling in any of the organs studied (brain, heart, lung, liverand kidneys) and regardless of the concentration used (100, 200, 300 and 500 μg/ml) while the isolated liver mitochondria from aged rats (18 months), an alteration is observed at all the complexes of the liver mitochondrial respiratory chain as well as the mitochondrial coupling regardless of the concentration used (250, 300 and 350 μg/ml), whereas for the young rats (3 months) no change is observed
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Duran, Nádia Marion. "X-ray spectroscopy uncovering the effects of Cu and Fe based nanoparticles on Phaseolus vulgaris L. germination and seedling development." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/64/64135/tde-13112018-150241/.
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Nanotechnology offers a great potential do design fertilizers with unique properties capable to boost the plant productivity. However, the nanoparticles environmental fate and their toxic responses still need to be deeply investigated to their safe use. This study aims to investigate the effect of copper oxide (nCuO) and magnetite nanoparticles (nFe3O4) on the germination and seedling development of Phaseolus vulgaris L. Seeds were treated in nanoparticles dispersions in a wide range of concentrations (1, 10, 100 and 1 000 mg L-1) and incubated in a germination chamber during 5 days. Different sized nCuO (25, 40 and <80 nm) and polyethylene glycol (PEG) coated nFe3O4 were evaluated. Although both nCuO and nFe3O4 treatments did not affected the germination rate, seedling weight gain was promoted by 40 nm CuO at 100 mg Cu L-1 and inhibited by 1 000 mg Cu L-1 of 25 nm CuO and positive control (CuSO4). Among the tested nCuO, the higher chemical reactivity was found for the 25 nm CuO, and this may partially explain the observed deleterious effects. Seeds treated in nFe3O4-PEG at 1 000 mg Fe L-1 increased radicle elongation compared to the negative control (water), while Fe2+/Fe3+ (aq) (positive control) and bare nFe3O4 at 1 000 mg Fe L-1 treatments reduced the radicle of the seedlings. The growth promoted by the PEG-coated nanoparticles can be justified by the higher water uptake induced by the PEG, and also by its lower chemical reactivity compared to the bare nanoparticles. This was reinforced by enzymatic assays since nFe3O4-PEG treatment was also the least harmful to the alpha-amylase activity. X-ray fluorescence spectroscopy (XRF) showed that most of the Cu and Fe incorporated by the seeds remained in the seed coat, specially in the hilum region, and X-ray tomography indicated that Fe3O4-PEG penetrated in this structure. X-ray absorption spectroscopy (XAS) unraveled that the Cu and Fe chemical environment of the nCuO and nFe3O4-PEG treated seeds persisted mostly in its primitive form. These results contribute to the understanding of how nCuO, nFe3O4 and nFe3O4-PEG interact with common bean seeds and seedlings and highlights its potential use in seed priming<br>A nanotecnologia oferece um grande potencial para o desenvolvimento de fertilizantes com propriedades únicas, capazes de impulsionar a produtividade das plantas. Contudo, o destino ambiental e os efeitos tóxicos das nanopartículas ainda necessitam ser profundamente investigados para o seu uso seguro. Este estudo visa investigar o efeito das nanopartículas de óxido de cobre (nCuO) e magnetita (nFe3O4) na germinação e desenvolvimento das plântulas de Phaseolus vulgaris L. As sementes foram tratadas em dispersões de nanopartículas em diversas concentrações (1, 10, 100 and 1 000 mg L-1) e incubadas em uma câmara de germinação durante 5 dias. Diferentes tamanhos de nCuO (25, 40 e <80 nm) e nFe3O4 recoberta com polietileno glicol (PEG) e foram avaliados. Embora ambos tratamentos de nCuO e nFe3O4 não afetaram a taxa de germinação, o ganho de massa das plântulas foi promovido pela nCuO de 40 nm à 100 mg Cu L-1 e inibido pelos tratamentos de nCuO de 25 nm e controle positivo (CuSO4) à 1 000 mg Cu L-1. Dentre as nCuO testadas, a maior reatividade química foi encontrada para a nCuO de 25 nm, e isso pode explicar parcialmente os efeitos deletérios desta nanopartícula. Sementes tratadas com nFe3O4-PEG à 1 000 mg Fe L-1 aumentaram o alongamento das radículas em comparação ao controle negativo (água), enquanto que os tratamentos Fe2+/Fe3+ (aq) (controle positivo) e nFe3O4 sem recobrimento à 1 000 mg Fe L-1 reduziram as radículas das plântulas. O crescimento promovido pelas nanopartículas recobertas com PEG pode ser justificado pela maior absorção de água induzido pelo PEG, e também pela sua baixa reatividade química comparada às nanopartículas sem recobrimento. Isso foi reforçado por ensaios enzimáticos uma vez que o tratamento de nFe3O4-PEG foi também o menos prejudicial à atividade da alfa-amilase. A espectroscopia de fluorescência de raios-X (XRF) mostrou que a maior parte do Cu e do Fe incorporados pelas sementes permaneceu no tegumento, especialmente na região do hilo, e a tomografia de raios-X indicou que nFe3O4-PEG penetrou nesta estrutura. A espectroscopia de absorção de raios-X (XAS) revelou que o ambiente químico do Cu e do Fe das sementes tratadas com nCuO e nFe3O4-PEG persistiram majoritariamente em sua forma primitiva. Estes resultados contribuem para o entendimento de como nCuO, nFe3O4 e nFe3O4-PEG interagem com sementes de feijão e destaca seu potencial uso no tratamento de sementes
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Matos, Izabela Teles de. "Caracterização em escala atômica de nanopartículas magnéticas de magnetita e ferrita do tipo TMFe2O4 (TM = Co, Ni) para uso em biomedicina pela espectroscopia de correlação angular gama-gama perturbada." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-30012019-144245/.
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Este trabalho descreve, sob um ponto de vista atômico, a investigação das nanopartículas magnéticas (NPMs) de magnetita (Fe3O4) e ferritas do tipo TMFe2O4 (TM = Co, Ni), que são uma classe de materiais estruturados que atualmente tem um grande interesse devido à grande variedade de suas possíveis aplicações tecnológicas e biomédicas, pela Espectroscopia de Correlação Angular γ-γ Perturbada (CAP). Para a produção das NPMs foram utilizadas duas rotas químicas: o método de co-precipitação e o método de decomposição térmica. A co-precipitação apresenta as vantagens de ter temperaturas moderadas e custos relativamente baixos, porém não se consegue ter um controle da distribuição de tamanho das partículas. Por outro lado, a decomposição térmica possibilita uma amostra monodispersa com controle de tamanho e forma, mas este método necessita de reagentes tóxicos, caros e alta temperatura de reação. Para caracterização das amostras foi usada a técnica de Difração de Raio X (DRX) e a morfologia das NPs foi estudada por meio da Microscopia Eletrônica de Transmissão (MET). A partir desta técnica foi possível avaliar a distribuição do tamanho dos grãos, pois algumas características como, elevado valor de magnetização, alta anisotropia e um alto valor de coercividade são propriedades que dependem das nanoestruturas. As propriedades magnéticas foram estudadas localmente a partir da Correlação Angular Perturbada (CAP) que utiliza como sondas núcleos atômicos das medidas, como os núcleos de prova 111In (111Cd), 140La (140Ce) e 181Hf(181Ta). Estas propriedades foram complementadas por medidas de Magnetização.<br>This work describes, from an atomic point of view, the investigation of magnetic nanoparticles (MNPs) of magnetite (Fe3O4) and ferrites of the type TMFe2O4 (TM = Co, Ni), which are a class of structured materials that currently have a great interest due to the great variety of its possible technological and biomedical applications by Perturbed γ-γ Angular Correlation Spectroscopy (PAC). Two chemical routes were used to produce MNPs: the co-precipitation method and the thermal decomposition method. Co-precipitation has the advantages of having moderate temperatures and relatively low costs, but particle size distribution control is not achieved. On the other hand, the thermal decomposition allows a monodisperse sample with size and shape control, but this method requires toxic reagents, expensive and high reaction temperature. The X-Ray Diffraction (XRD) technique was used to characterize the samples and the morphology of the NPs was studied by Electron Transmission Electron Microscopy (TEM). From this technique it was possible to evaluate grain size distribution, because some characteristics such as high magnetization value, high anisotropy and a high coercivity value are properties that depend on the nanostructures. The magnetic properties were studied locally from the Perturbed Angular Correlation (CAP), which uses as probe nuclei of the measurements, such as 111In (111Cd), 140La (140Ce) and 181Hf (181Ta). These properties were complemented by Magnetization measurements.
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Nunes, Eloiza da Silva [UNESP]. "Preparação e caracterização de nanocompósitos de Fe@SiO2, Fe@Fe3O4 e Fe3O4@PNIPAM." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/124538.
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000826270.pdf: 25046020 bytes, checksum: fb29338aa8631d88b7bca10a5d22a9be (MD5)<br>Neste trabalho foi investigada a obtenção de nanopartículas de ferro metálico em diferentes meios não aquosos (glicóis) e em água através da rota de redução com boroidreto e a obtenção de estruturas caroço@casca Fe@SiO2 e Fe@Fe3O4. Também são apresentados resultados da caracterização de nanocompósitos magnéticos à base poli(N-isopropilacrilamida) (PNIPAM) e de nanogéis poliméricos (controles) através do método de polimerização radicalar por precipitação. A composição dos nanocompósitos poliméricos foi variada quanto ao tipo de co-monômero (ácido acrílico e poli(etileno glicol) metiléter metacrilato (PEGMA)), reticulador (metileno bis-acrilamida (MBA) e poli(etileno glicol) diacrilato (PEGDA)) e nanopartícula magnética precursora. As nanopartículas metálicas e nanoestruturas Fe@SiO2 e Fe@Fe3O4 foram caracterizadas por DRX, espectroscopia Mössbauer, XPS, SEM e TEM. Os resultados obtidos demostraram que as nanopartículas de ferro metálico foram compostas de α-Fe e variáveis teores de liga de Fe1-xBx e a morfologia e tamanho de partícula variaram em função dos diferentes meios reacionais empregados. As metodologias de recobrimento das partículas metálicas precursoras foram eficazes na estabilização química do caroço magnético. O recobrimento com sílica para obtenção das estruturas Fe@SiO2 foi realizado empregando-se precursores alcoxissilanos através do processo sol-gel. A espessura da camada de sílica pode ser controlada mais eficientemente no caso de partículas maiores oriundas de redução no meio aquoso e no caso de nanopartículas pequenas observou-se a formação de agregados. As estruturas Fe@Fe3O4 foram obtidas pela passivação das nanopartículas metálicas em solvente glicol. A metodologia de passivação demostrou a possiblidade de oxidação controlada da superfície para fase de magnetita evitando a formação de óxi-hidróxidos não...<br>In this work the obtainment of metallic iron nanoparticles in several non-aqueous (glycols) and in aqueous media through chemical reduction with sodium borohydride and the obtainment of core@shell structures Fe@SiO2 and Fe@Fe3O4, was investigated. The characterization results of poly(N-isoproprylacrylamide) (PNIPAM) based magnetic nanocomposites and bare polymeric nanogels (controls) synthesized through radical precipitation polymerization were also presented. The composition of the polymeric nanocomposites was varied as the type of co-monomer (acrylic acid and poly(ethyleneglycol) methylether methacrylate (PEGMA)), crosslinker (methylene bis-acrylamide (MBA) and poly(ethyleneglycol) diacrylate (PEGDA)) and precursor magnetic nanoparticle. The metallic nanoparticles and the core@shell Fe@SiO2 and Fe@Fe3O4 nanostructures were characterized by XRD, Mössbauer spectroscopy, XPS, SEM and TEM. The results show that the iron nanoparticles were composed of α-Fe and varying amounts of Fe1-xBx alloy and the size and morphology of the particles was dependent of the reaction media used. The strategies for metallic nanoparticles coating was efficient and chemically stabilized the magnetic cores. The Fe@SiO2 nanostructures was prepared by using alkoxysilanes precursors through the sol-gel process to produce the silica coating. The silica thickness could be controlled more efficiently in the case of bigger particles produced from chemical reduction in aqueous media. In the case of small nanoparticles the formation of aggregates was observed. The Fe@Fe3O4 core@shell structures were obtained by passivation of the metallic iron nanoparticles in a glycol solvent. The method of passivation enabled good oxidation control of the metallic surface to magnetite phase, avoiding the formation of non-magnetic oxy-hydroxides. The metallic to oxide phase ratio was determined by Rietveld refinement and was dependent of the type...
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CATALANO, ENRICO. "Physicochemical and biological characterization of magnetic nanoparticles for biomedical applications." Doctoral thesis, Università del Piemonte Orientale, 2015. http://hdl.handle.net/11579/81662.
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The overall goal of this project was the biological characterization by in vivo and in vitro testing of magnetic nanoparticles that can be used for various applications. The aim of this work was to understand which of the synthesized magnetic nanoparticles could be more suitable to be used as a carrier or platform for various applications in different scientific fields. Two different kinds of magnetic nanoparticles were developed: naked iron-oxide nanoparticles and silica or silica-based coated nanoparticles (core shell-type nanoparticles). Magnetic nanoparticles were prepared using a coprecipitation method. The structure, phase composition, physicochemical and surface properties, magnetic susceptibility, and release in vitro of MNPs were characterized by transmission electron microscopy, x-ray diffraction, scanning electron microscopy-energy dispersive x-ray spectroscopy, and a vibrating sample magnetometer. In vivo toxicity, in vitro toxicity, ROS production and genotoxicity were investigated. Therapeutic effects were evaluated by cell viability assays and flow cytometry assays. The tools developed in this thesis spanned a range of physical-chemical, biological and magnetic aspects and incorporate innovations on a nanometric range of scales. MNP-based technologies appear to hold a significant potential for a myriad of biomedical applications and the toxic potential of MNPs cannot be overlooked. For this reason we carried out different physicochemical and biological characterization of MNPs to identify a safe dose and formulation of MNPs. Understanding the relationship between the physicochemical properties of MNP constructs and their behavior will induce full translational potential of these nanoparticles. The magnetic nanoparticles prepared in this study have good biocompatibility and are suitable for further application in tumor hyperthermia.
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Huet, Sarah Damasceno Pinheiro. "Estudo das interações hiperfinas em nanopartículas de Fe3O4 e Fe3O4 dopadas com gadolínio pela espectroscopia de correlação angular perturbada." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-20062014-132040/.
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Neste trabalho foram estudadas as nanopartículas magnéticas (NPs) de interesse em biomedicina de Fe3O4 e de Fe3O4 dopadas com Gd 5% pela técnica de Espectroscopia de correlação angular gama-gama perturbada (CAP). As amostras de Fe3O4 foram sintetizadas pelos métodos de co-precipitação e decomposição térmica e as nanopartículas de Fe3O4 dopadas com Gd 5% foram sintetizadas pelo método da coprecipitação. As amostras de nanoparticulas foram caracterizadas quanto a sua estrutura pela difração de raios X (DRX) e quanto ao seu tamanho pela técnica de microscopia eletrônica de transmissão (TEM). Os resultados mostram que as nanoparticulas de ferrita mostram estrutura pertencente ao grupo espacial Fd3m e que seu tamanho é de 10 nm quando sintetizada por decomposição térmica e entre 7 e 15 nm quando sintetizada por co-precipitação. As nanopartículas de Fe3O4 sintetizadas pelo método de decomposição térmica apresentaram maior monodispersão do que as nanopartículas sintetizadas pelo método de co-precipitação, ou seja, o tamanho de grão estava mais homogêneo. A técnica CAP mostrou que a variação de tamanho das nanopartículas infuencia no comportamento magnético das mesmas e o dopante Gd atrapalha a introdução da sonda radioativa por competir pelos sítios de Fe.<br>In the work reported in this dissertation, magnetic nanoparticles of Fe3O4 and 5% Gddoped Fe3O4, which have applications in biomedicine, were studied by Perturbed Gamma-Gamma Angular correlation spectroscopy (PAC). Fe3O4 samples were synthesized by both, co-precipitation and thermal decomposition methods. Gd-doped Fe3O4 magnetic nanoparticles were synthesized only by co-precipitation method. Analysis of X-ray diffraction (XRD) showed that the samples belong to Fd3m space group. Transmission Electron Microscopy (TEM) showed that nanoparticles have sizes between 5 and 14 nm, suitable for biomedical applications. Fe3O4 nanoparticles synthesized by thermal decomposition method showed greater monodispersed nanoparticles than the samples synthesized by co-precipitation method. PAC technique using radioactive probe 111In (111Cd) showed that the size of the nanoparticles changes magnetic behavior and for the Gd-doped sample PAC measurements results showed that the introduction of radioactive probe is difficult due the presence of an impurity (Gd) and there is a competition for Fe sites between Gd and nuclear probe.
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Ballesteros, Camilo Arturo Suarez. "Síntese e caracterização de nanopartículas Fe3O4@Au e desenvolvimento de sensores para aplicações em nanomedicina." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-23102012-101205/.
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Com o desenvolvimento de novos nanomateriais têm-se descoberto propriedades eletrônicas, elétricas, ópticas e catalíticas únicas para aplicações nanotecnológicas. Entre estes nanomateriais com caraterísticas singulares, estão as nanopartículas (Np) CoreαShell, as quais combinam propriedades físico-químicas de dois materiais diferentes, provendo maior eficiência em aplicações como nanoeletrônica, sensoreamento, biossensoreamento e biomédicas. Neste trabalho, Np CoreαShell são sintetizada com núcleo (Core) de Np Fe₃O₄ e com casca (Shell) de Np Au, formando as Nps Fe₃O₄αAu na presença do dendrímero poli(amidoamina) geração 4.0 (Pamam G4). As propriedades físico-químicas do nanomaterial core-shell são estudadas através de análises espectroscópicas, microscopias e eletroquímicas, além de medidas de magnetização. Essas técnicas revelam a formação das Nps Au nas cavidades do Pamam G4 e as interações eletrostáticas entre os grupos funcionais do Pamam G4 e os grupos OH ⁻ e H ⁺ da superfície das Nps magnéticas, as quais dão uma forte estabilidade na configuração da Np Fe₃O₄αAu. Evidencia-se propriedades óticas da Np Au e propriedades superparamagnéticas da Np Fe ₃ O ₄, as quais podem ser usadas para aplicações em nanomedicina. As propriedades electrocatalíticas das Nps são utilizadas na detecção de dopamina (DA). Foram fabricados sensores eletroquímicos das Nps Fe₃O₄αAu, Nps Fe₃O₄ e Nps Au, e caracterizados por técnicas de voltametria cíclica e voltametria de pulso diferencial. A fabricação dos sensores consistiu na deposição de camadas alternadas entre as nanopartículas com o poliânion poly(ácido vinil sulfônico) (PVS) no eletrodo de ITO, levando à configuração de três arquiteturas; ITO - (Fe₃O₄αAu ⁄ PV S), ITO - (Fe₃O₄ ⁄ PV S) e ITO - (Au ⁄ PV S). Um problema encontrado na detecção de DA é que esta tem potenciais de oxidação aproximadamente iguais ao ácido ascórbico (AA) e ao ácido úrico (AU). Portanto, os sensores utilizados na detecção de DA, devem ser altamente seletivos a DA em relação a seus interferentes. Os sensores desenvolvidos aqui mostraram uma boa seletividade e velocidade de resposta na detecção de DA, sendo o sensor ITO - (Fe₃O₄αAu ⁄ PV S) o mais eficiente. As Nps Fe₃O₄αAu revelam maior citotoxicidade nas células cancerígenas comparadas com as células saudáveis, já que as células cancerígenas são mais sensíveis ao estresse oxidativo produzido pelas nanopartículas no interior da célula.<br>Along with the development of nanomaterials came the knowledge and design of their unique eletronic, optical and catalitycal properties which may be used for a variety of nanotecnological applications. A special class of nanomaterials with interesting characteristics is represented by the CoreαShell nanoparticles, which combine the physicochemical properties of two differerent nanomaterials (including oxides, metals, semiconductors or polymers). This combination provides greater efficiency in applications such as nanoelectronics, sensing, biosensing and biomedical areas. This study reports the synthesis of Fe₃O₄ Np, which in the presence of the polyamido amine generation 4.0 (Pamam G4), is covered with Au Np forming the Fe₃O₄αAu Nps. The nanomaterials had been characterized using spectroscopic, microscopic and electrochemical techniques. The results revealed the formation of Au Nps in the cavities of PAMAM G4 and showed that the electrostatic interactions between the PAMAM functional groups and the OH ⁻ and H ⁺ groups on the surface of the magnetic nanoparticles lead to a strong stability in the configuration of Fe₃O₄αAu Nps. The optical properties of the Au Np (namely the Plasmon resonance band at 542 nm) as well as the superparamagnetic properties of the Fe₃O₄ Np were present in the core-shell nanostrutures. Due to their electrocatalytical properties, the core-shell nanoparticles were employed as active elements for dopamine (DA) detection. The fabrication of the modified electrodes for DA detection consisted in the deposition by LbL technique of alternating layers of nanoparticles and poly(vinyl sulfonic acid) (PVS) on the ITO eletrode, in three distinct architectures: ITO - (Fe₃O₄αAu Fe₃O₄ PV S), ITO - (Fe₃O₄ ⁄ PV S) and ITO - (Au ⁄ PV S). We found a good selectivity and rapid response toward the detection of DA, being the sensor ITO - (Fe₃O₄αAu ⁄ PV S) the most efficient. The effect of Fe₃O₄αAu Nps showed a higher cytotoxicity in cancer cells compared to healthy cells, because cancer cells are more sensitive to oxidative stress produced by the nanoparticles.
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Khan, Muhammad Younas. "Synthesis and characterization of superparamagnetic nanoparticles containing Fe3O4 core in pyrolyzed tannin." reponame:Repositório Institucional da UFPR, 2015. http://hdl.handle.net/1884/37621.
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Orientador : Dr. Antonio Sálvio Mangrich<br>Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa: Curitiba, 12/03/2015<br>Inclui bibliografia<br>Área de concentração: Inorganic Chemistry<br>Resumo: A nanotecnologia é uma ciência de engenharia em que o objetivo é desenvolver
procedimentos e estruturas em nanoescala, com novas propriedades que podem
oferecer soluções para muitos problemas atuais. Nesta pesquisa, descrevemos a
síntese de nanopartículas de óxido de ferro superparamagnético (Fe3O4). As
nanopartículas de óxido de ferro contêm um núcleo de óxido de ferro, que é cercado
por um escudo de ligantes. O escopo deste trabalho foi a preparação de
nanopartículas superparamagnéticas baratas e revestidas com extrato de tanino
condensado pirolisado extraído de Acacia mearnsii formando nanopartículas
estruturadas num núcleo-camada de cobertura, usando um processo de coprecipitação
de passo único. Extrato seco de tanino de foi por terra e blindados
(usando uma peneira de malha-80), e 200 g por litro foi adicionado a uma solução
aquosa contendo cloreto férrico e cloreto ferroso relação molar de 2:1 em um meio
básico de pH = 10. A mistura foi agitada vigorosamente por 30 minutos. Após a
formação de precipitado, ele foi separado por centrifugação e depois de secar o
precipitado foi pirolisado na temperatura desejada 400 °C ou 700 °C,
respectivamente, a taxa de 5 ° C/min por 6 h. A caracterização do material
preparado foi realizada utilizando espectroscopia de infravermelho com
transformada de Fourier (FTIR), microscopia eletrônica de varredura (MEV),
microscopia eletrônica de transmissão (TEMPLETON et al.), difração de raios x
(XRD) e análise de Brunauer-Emmett-Teller (BET). As nanopartículas
superparamagnéticas de óxido de ferro em tanino pirolisado (SPMIOBNPs)
apresentaram tamanhos médios na faixa de 20-35 nm determinados com a ajuda
da XRD e equação de Scherrer. As análises de BET e SEM confirmaram que a
superfície das SPMIOBNPs apresentavam estrutura porosa, com multicamadas de
microporos e isoterma do tipo H(III). As SPMIOBNPs preparadas mostraram
atração muito forte em direção de campo magnético externo, usando
espectroscopia de EPR, ou disco do ímã de neodymium. As propriedades
magnéticas revelaram que os SPMIOBNPs eram superparamagnéticas, com
saturação de magnetização de 32 emu/g a 300 K utilizando magnetômetro SQUID.
O desempenho das SPMIOBNPs na limpeza de águas mostraram um bom
resultado na remoção de cromo hexavalente [Cr(VI)] da água contaminada. Os
resultados mostraram que a adsorção de Cr(VI) pelas SPMIOBNPs era dependente
pH, sendo que as maiores adsorções se deram no menor pH da solução de valor
2. O estudo por espectroscopia de fotoeletrônica de raios x (XPS) mostrou que que
a maior parte do Cr(VI) adsorvido foi reduzido a Cr(III). Neste estudo, podemos
concluir que SPMIOBNPs têm o potencial de remoção de cromo hexavalente de
águas residuais. O equilíbrio cinético do processo de sorção também foi
investigado. A sorção de Cr(VI) pelas SPMIOBNPs preparadas seguiu o modelo
cinético de pseudo - segunda ordem sugerindo que a taxa de reação de sorção
depende de dois parâmetros, que podem ser a concentração do sorbato e dosagem
do adsorvente. Segundo modelo de ordem indica que ’Quimissorção’ ocorreu
durante o processo de adsorção ou seja, uma nova espécie químicos foram criados
na superfície do adsorvente.
Palavras-chave: Nanotecnologia, superparamagnético, biocarvão, tanino,
co-precipitação, cromo hexavalente.<br>Abstract: Nanotechnology is an engineering science in which the aim is to develop
procedures and structures at the nanoscale, with novel properties that might
offer solutions to many current problems. In this research, we describe the
synthesis of superparamagnetic iron oxide (Fe3O4) nanoparticles. Iron oxide
nanoparticles contain a core of iron oxide which is surrounded by a shell of
ligands. The scope of this work is a preparation of cheap superparamagnetic
nanoparticles and coating them with extract of condensed tannin extract of
Acacia mearnsii to form core-shell structured biochar nanoparticles, using a
single step co-precipitation process. Dry tannin extract of was ground and
screened (using an 80-mesh sieve), and 200 g per liter was added to an aqueous
solution containing ferric chloride and ferrous chloride 2:1 molar ratio at a basic
medium of pH =10. The mixture has been vigorously stirred for 30 minutes. After
the formation of precipitate it was separated by centrifugation and after drying
the precipitate was pyrolysed on desired temperature 400 °C and 700 °C
respectively at a rate of 5 °C/min for 6 h. Characterization of this material
(acronym: SPMIOBNPs) was performed using Fourier transform infrared
spectroscopy (FTIR), scanning electron microscopy (SEM), transmission
electron microscopy , X-ray diffraction (XRD) and Brunauer–Emmett–Teller
(BET) analysis. The SPMIOBNPs particles produced were contained iron oxide
nanoparticles with average sizes in the range of 20-35 nm determined with help
of XRD and Scherrer equation. The XRD diffractogram suggest the. SEM and BET
analysis confirm its porous, multilayer micropores structure surface with H(III)
type of isotherm. The FTIR analysis give an idea about the changes take place
in the structure after pyrolysis attributing the formation SPMIOBNPs with
characteristic functional groups. SPMIOBNPs prepared shows very strong
attraction toward external magnetic field using a disc of neodymium magnet. The
magnetic properties revealed that the SPMIOBNPs were superparamagnetic,
with a saturation magnetization of 32 emu/g at 300 K using vibrating sample
magnetometer SQUID. The performance of the SPMIOBNPs show a good result
in the removing of hexavalent chromium Cr(VI) from contaminated water. The
detection of total chromium in the solution was analyzed with the help of flame
atomic absorption and hexavalent chromium was done with the help of 1,5-
diphenylcarbohydrazide method. Equilibrium, kinetics, of the sorption process
were also investigated which show some reduction of Cr(VI) to Cr(III). The
results showed that Cr(VI) adsorption on SPMIOBNPs was dependent on lower
pH of the solution i.e. 2. The X-ray photoelectron spectroscopy (XPS) study
showed that during Chromium adsorption, some amount Fe(II) was transformed
into Fe(III) by the redox reaction and Cr(VI) species were reduced to Cr(III)
species. In this study we conclude that SPMIOBNPs have potential in removal
of chromium hexavalent from waste water. The sorption kinetics of Cr(VI) onto
SPMIOBNPs are followed the pseudo-second order kinetic model suggesting
that the sorption reaction rate depends on two parameters, which might be the
sorbate concentration and sorbent dosage. Second order kinetic model indicates
that ’Chemisorption’ took place during the adsorption process i.e. a new chemical
species were created at the adsorbent surface.
Key-words : Nanotechnology, superparamagnetic, biochar, tannin, coprecipitation,
hexavalent chromium.
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Patel, Ronakkumar S. "Development, Characterization, and Magnetic Hypothermia Behaviors of Engineered Fe3O4 Nanocomposites for Biomedical Applications." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1368024719.
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Macêdo, Gleyguestone Lopes de 1983. "Síntese e caracterização magnética de nanopartículas do tipo dímero de Ag-Fe3O4." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278116.
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Orientador: Kleber Roberto Pirota<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin<br>Made available in DSpace on 2018-08-20T23:05:11Z (GMT). No. of bitstreams: 1
Macedo_GleyguestoneLopesde_M.pdf: 4864713 bytes, checksum: a6eff7f69f1d64274cacac58dc118e5c (MD5)
Previous issue date: 2012<br>Resumo: Neste trabalho, seguindo uma nova rota de síntese, foram produzidas três amostras de nanopartículas do tipo dímero de prata com magnetita (Ag-Fe3O4), onde a única diferença entre elas é no valor da concentração de partículas de prata utilizadas na síntese. As amostras de tipo dímero possuem concentrações de prata iguais a 0,003 g/mL, 0,007 g/mL e 0,01 g/mL e foram chamadas, respectivamente, de AgFeO_1, AgFeO_2 e AgFeO_3. Sobre estes sistemas realizaram-se medidas da magnetização do tipo Zero Field cooling/Field cooling (ZFC-FC) onde se observou nos três sistemas um aumentou brusco da temperatura de irreversibilidade (Tirr) da magnetita quando unida a prata. Também se observou que somente na amostra com menor concentração de prata sofre um grande aumento em sua temperatura de bloqueio (T B), aproximadamente 130K, que pode ser devido a fatores como aumento do tamanho da partícula de magnetita contida no dímero, aglomerações e interações entre particulas. Porém, através de medidas de dicroísmo circular magnético de raios-X (XMCD) observou-se que com a união da prata a magnetita provoca nesta um aumento de seu momento orbital sendo mais intenso para a amostra com menor concentração de prata (AgFeO_1). Tal resultado pode explicar o aumento em Tirr e TB, já que o momento orbital é diretamente proporcional à anisotropia magnética. Por fim, gostaria de salientar que, em conjunto com meu orientador (Prof. Kleber Roberto Pirota) foi decidido optar por uma estrutura na qual inicio com descrição das bases teóricas de interesse, logo comento rapidamente sobre as técnicas experimentais utilizadas e, finalmente, anexo os trabalhos publicados. Porém, como alguns resultados obtidos neste trabalho ainda não foram publicados, decidi resumir-los no final da tese (capítulo 4)<br>Abstract: In this work, following a new synthesis route, three samples were produced nanoparticle type silver dimer with magnetite (Ag-Fe3O4), where the only difference between them is the value of the concentration of silver particles used in the synthesis. Samples of dimer type silver concentrations have equal 0,003 g/mL, 0,007 g/mL e 0,01 g/mL and were named, respectively AgFeO_1, and AgFeO_2 AgFeO_3. On these systems were expressed as the magnetization of the type Zero Field cooling/Field cooling (ZFC-FC) where it was observed in all three systems a sudden increase in temperature of irreversibility (T IRR) of magnetite attached to silver. It was also observed that the sample with only low silver concentration undergoes a sharp increase in its temperature block (TB), to approximately 130K, which may be due to factors such as increasing the particle size of magnetite contained in the dimer interactions and agglomerations. However, through measures of magnetic circular dichroism X-ray (XMCD) observed that with the union of silver magnetite causes this increased their orbital momentum being more intense for the sample with lower concentration of silver (AgFeO_1). This result may explain the increase in TB and TIRR, since the orbital momentum is directly proportional to the magnetic anisotropy. Finally, let me emphasize that, together with my advisor (Prof. Kleber Roberto Pirota) it was decided to opt for a structure in which beginning with a description of the theoretical bases of interest, just comment quickly on the experimental techniques used and eventually annex published works. However, as some results of this work have not yet been published, I decided to summarize them at the end of the thesis (Chapter 4)<br>Mestrado<br>Física<br>Mestre em Física
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Thomas, Guillaume. "Nanoparticules de magnétite fonctionnalisées pour l'imagerie bimodale IRM/TEP." Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS029/document.
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Nanoparticules de magnétite fonctionnalisées pour l’imagerie bimodale IRM/TEPLes nanoparticules d’oxydes de fer superparamagnétiques (SPIONs en anglais) font l’objet de recherches intenses dans le domaine biomédical, notamment comme nanomédicament et agent de contraste T2 en imagerie par résonance magnétique (IRM). Au cours de cette étude, des nanoparticules de magnétite (Fe3O4) à destination de l’imagerie IRM/TEP (Tomographie par Emission de Positons) ont été développées. Dans un premier temps, des SPIONs modifiées en surface, stables et superparamagnétiques ont été synthétisées via un dispositif hydrothermal en continu. A leur surface ont été greffées, durant la synthèse, des molécules hydrophiles : l’acide citrique, la LDOPA, le DHCA et le PHA. La fonctionnalisation des nanoparticules a été optimisée en modifiant des paramètres de synthèse tels que la température et le lieu de mélange, occasionnant des modifications de morphologie, taille et phase. Dans un second temps, pour améliorer leur stabilité et furtivité, des polymères de type PolyEthylène Glycol (PEG) ont été greffés à leur surface, deux longueurs de chaîne ont été évaluées. Pour une application en TEP, des macrocycles, complexant le radionucléide 64Cu, tels que le MANOTA, le NODAGA et le DOTA ont été couplés à ces SPIONs. Les essais de radiomarquage sont concluants. Ces nanohybrides, pleinement caractérisés (MET, XPS, IR, DLS, potentiels zêta, ATG, Raman) sont très prometteurs pour le diagnostic via l’imagerie bimodale IRM/TEM, notamment le composé Fe3O4-LDOPA-NODAGA (øDLS = 85±1 nm, r2 = 197±7 mM.s-1, 87% 64Cu). Des études préliminaires de cytotoxicité et génotoxicité de SPIONs modifiés par de l'APTES ont également été réalisées via des biotests très sensibles et novateurs<br>Functionalized magnetite nanoparticles for bimodal MRI/PET imagingSuperParamagnetic Iron Oxide Nanoparticles (SPIONs) have been widely studied in the biomedical field due to their promising application as nanodrugs and MRI (Magnetic Resonance Imaging) contrast agents (T2). In this study, magnetite (Fe3O4) nanoparticles have been developed for use as contrast agents for MRI/PET (Positron emission tomography) double imaging. First, functionalized stable superparamagnetic SPIONs have been synthesized in a continuous hydrothermal reactor. During the synthesis, hydrophilic agents (citric acid, LDOPA, DHCA and PHA) have been grafted on the surface of the nanoparticles. The functionalization of the nanoparticles has been optimized by modifying various synthesis parameters such as the temperature and the addition sequence of the organic molecules. The morphology, the size and the structure of the nanoparticles have been shown to depend on these different parameters. Then PolyEthylene Glycol (PEG) polymers have been grafted on their surface to make them stealth and biocompatible. Two different lengths have been considered. For PET imagery, macrocycles which are chelating agents of the 64Cu radionuclide such as MANOTA, NODAGA and DOTA have been grafted on these SPIONs. The radiochemical purities are very conclusive. These nanohybrids have been extensively characterized (TEM, XPS, IR, DLS, ?-potential, TGA, Raman) and are very promising as a diagnostic tool for bimodal imaging MRI/PET in particular the Fe3O4-LDOPA-NODAGA nanoplatform (øDLS = 85±1 nm, r2 = 197±7 mM.s-1, 87% 64Cu). Preliminary cytotoxicity and genotoxicity studies on SPIONs modified by APTES have also been performed via very sensitive and innovative biotests
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Garcia, Cécile. "Synthèse de nanoparticules par voie électrochimique." Toulouse 3, 2006. http://www.theses.fr/2006TOU30179.
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Ce travail porte sur la synthèse de nanoparticules (NPs) d’alliage métallique Ni-Co et de Fe3O4 réalisées par une méthode électrochimique dans un milieu éthanol-eau. L’étude et l’optimisation du procédé de synthèse ont permis de produire des NPs de Ni/Co, en forme de bâtonnets, stabilisées par un tensioactif. Une étude expérimentale systématique a mis en évidence un lien entre les paramètres utilisés lors de la synthèse (densité de courant, % d’eau dans la solution, durée de synthèse, concentration des réactifs) et la morphologie ainsi que la structure de ces nano-bâtonnets de Ni/Co. De même, des NPs de Fe3O4, sphériques et bien calibrées en taille (2-5 nm) ont été obtenues grâce à un nouveau procédé basé sur l’électro-précipitation directe d’oxyde dans l’éthanol. Ce dispositif permet la production de NPs quasi-monodisperses dans un milieu éthanol sans la présence d’aucun agent stabilisant. Pour caractériser ces différents NPs, nous avons systématiquement utilisé la MET et le WAXS<br>This thesis deals with the synthesis of metallic (Ni-Co alloy) and oxide (Fe3O4), nanoparticles elaborated by an electrochemical process in ethanol medium. The study and the optimization made on the process lead to produce bimetallic nanoparticles of Ni/Co stabilized by surfactant with a rod-like morphology. A systematic experimental study shows clear relation between the synthesis parameters (current density, water percentage in ethanol, synthesis time, reagent concentration) and the morphology and structure of these Ni/Co nano-rods or wires. Magnetite (Fe3O4) nanoparticles were also obtained using a new process based on direct electro-precipitation of an oxide in a dry solvent. This very simple process allows to produce quasi-monodisperse spherical nanoparticles (2-5 nm) in an ethanol medium without any stabilizing agent. To characterize these various nanoparticles, we systematically used transmission electron microscopy and wide-angle X-ray scattering
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Liong, Silvia. "A Multifunctional Approach to Development, Fabrication, and Characterization of Fe3O4 Composites." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7640.
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A unique approach for lightweight multifunctional composites was developed using Fe3O4 nanoparticles and polypyrrole-coated Fe3O4 particles as fillers. Fe3O4 particles are a good candidate for filler in a multifunctional composite system because they can reinforce mechanical properties of a polymer matrix and impart magnetic properties into a composite. Polypyrrole coating on Fe3O4 particles was utilized to incorporate electrical conductivity to the properties of composites. The effects of filler size and filler content were studied on both the mechanical and electromagnetic properties. Fe3O4 nanoparticles improved fracture toughness, but they compromised strength and modulus. Polypyrrole-coated Fe3O4 has potential for multifunctional material applications because the coating allows for concurrent increase in magnetic permeability and electrical conductivity in a composite. The polypyrrole coating also improved the strength of the composite. Fe3O4 nanoparticles were a major part of this work from their synthesis to their application in composites. The surface effect on magnetic properties was analyzed for Fe3O4 nanoparticles, resulting in a more accurate calculation of the magnetically dead layer thickness than previously reported. The results from this work contributed to further understanding of synthesis and characterization of magnetic nanoparticles, fabrication and characterization of nanocomposites, and design and development of lightweight multifunctional materials. Although the properties of the fabricated composites require further improvement, the methodology and approach provide a basis for future work in development of lightweight multifunctional composites.
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Ansari, Farahnaz. "Use of magnetic nanoparticles to enhance biodesulfurization." Thesis, Cranfield University, 2008. http://dspace.lib.cranfield.ac.uk/handle/1826/4424.
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Biodesulfurization (BDS) is an alternative to hydrodesulfurization (HDS) as a method to remove sulfur from crude oil. Dibenzothiophene (DBT) was chosen as a model compound for the forms of thiophenic sulfur found in fossil fuels; up to 70% of the sulfur in petroleum is found as DBT and substituted DBTs; these compounds are however particularly recalcitrant to hydrodesulfurization, the current standard industrial method. My thesis deals with enhancing BDS through novel strains and through nanotechnology. Chapter highlights are: Chapter 2. My first aim was to isolate novel aerobic, mesophilic bacteria that can grow in mineral media at neutral pH value with DBT as the sole sulfur source. Different natural sites in Iran were sampled and I enriched, isolated and purified such bacteria. Twenty four isolates were obtained that could utilize sulfur compounds. Five of them were shown to convert DBT into HBP. After preliminary characterization, the five isolates were sent to the Durmishidze Institute of Biotechnology in Tbilisi for help with strain identification. Two isolates (F2 and F4) were identified as Pseudomonas strains, F1 was a Flavobacterium and F3 belonged to the strain of Rhodococcus. The definite identification of isolate F5 was not successful but with high probability it was a known strain. Since no new strains were apparently discovered, I did not work further in this direction. Chapter 3. In a second approach I studied the desulfurization ability of Shewanella putrefaciens strain NCIMB 8768, because in a previous investigation carried out at Cranfield University, it had been found that it reduced sulfur odour in clay. I compared its biodesulfurization activity profile with that of the widely studied Rhodococcus erythropolis strain IGTS8. However, S. putrefaciens was not as good as R. erythropolis. Chapter 4 and 5. I then turned to nanotechnology, which as a revolutionary new technological platform offers hope to solve many problems. There is currently a trend toward the increasing use of nanotechnology in industry because of its potentially revolutionary paths to innovation. I then asked how nanotechnology can contribute to enhancing the presently poor efficiency of biodesulfurization. Perhaps the most problematic difficulty is how to separate the microorganisms at the end of the desulfurization process. To make BDS more amenable, I explored the use of nanotechnology to magnetize biodesulfurizing bacteria. In other words, to render desulfurizing bacteria magnetic, I made them magnetic by decorating their outer surfaces with magnetic nanoparticles, allowing them to be separated using an external magnet. I used the best known desulfurizing bacterial strain, Rhodococcus erythropolis IGTS8. The decoration and magnetic separation worked very well. Unexpectedly, I found that the decorated cells had a 56% higher desulfurization activity compared to the nondecorated cells. I proposed that this is due to permeabilization of the bacterial membrane, facilitating the entry and exit of reactant and product respectively. Supporting evidence for enhanced permeabilization was obtained by Dr Pavel Grigoriev, Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino. In Chapter 6, to optimize attachment of the nanoparticles to the surface of the bacteria I created thin magnetic nanofilms from the nanoparticles and measured the attachment of the bacteria using a uniquely powerful noninvasive optical technique (Optical Waveguide Lightmode Spectroscopy, OWLS) to quantify the attachment and determine how the liquid medium and other factors influence the process.
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Sadat, Md Ehsan. "Probing the Magnetic Relaxation Dynamics and Optical Properties of Superparamagnetic Iron-Oxide (Fe3O4) Nanoparticles for Biomedical Applications." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1447689870.
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Maurizi, Lionel. "Elaboration de nanoparticules fonctionnelles : applications comme agents de contraste en IRM." Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00656844.
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Les nanoparticules d'oxyde de fer de structure spinelle ouvrent de nombreuses voies dans le domaine biomédical. Parmi les applications possibles, les propriétés superparamagnétiques des cristallites d'une dizaine de nanomètres permettent de les utiliser pour le diagnostic médical, notamment en Imagerie par Résonance Magnétique (IRM).Ce travail a consisté à élaborer des suspensions colloïdales de nanoparticules de magnétite ou de maghémite (nommées USPIO pour Ultrasmall SuperParamagnetic Iron Oxide) compatibles avec les conditions physiologiques (pH = 7,4 et [NaCl] = 0,15 M).Par co-précipitation classique, des USPIO, de taille de cristallites de 8 nm, de surface spécifique de 110 m².g-1 et agrégés en assemblages d'environ 20 nm ont été obtenus. Pour stabiliser ces nano-objets, deux voies ont été explorées. Des agents électrostatiques (acide citrique et DMSA) ont modifié la charge nette de surface des oxydes de fer. La stabilisation stérique a également été explorée par greffage de méthoxy-PEG couplés à des fonctions silanes (mPEG-Si). Par combinaison de mPEG2000-Si et de DMSA, des suspensions stables ont également été obtenues. De plus, les fonctions thiols apportées par le DMSA et présentes à la surface des agrégats se trouvent protégées de leur oxydation naturelle par l'encombrement stérique des chaînes de polymère (la formation de ponts disulfures est évitée). La post-fonctionnalisation de ces nanoparticules via ces fonctions thiols est alors possible plusieurs semaines après leur synthèse. Ce concept a été validé par post-greffage d'un fluorophore (0,48 RITC/nm²) pour la détection in vitro en microscopie à fluorescence.En parallèle de cette étude en " batch ", des nanoparticules d'oxyde de fer ont été synthétisées en continu à l'aide d'un procédé hydrothermal pouvant s'étendre au domaine eau supercritique. En voie hydrothermale classique, des USPIO stabilisés par des ions citrates ont été obtenus en continu. Grâce aux propriétés physicochimiques de l'eau supercritique, la co-précipitation de magnétite a été possible sans l'utilisation de base.La cytotoxicité et l'internalisation cellulaire de ces USPIO ont été évaluées sur trois modèles cellulaires (macrophages RAW, hépatocytes HepG2 et cardiomyocytes) et les efficacités comme agents de contraste en IRM de ces nanoparticles ont été mesurées sur gel et sur modèle murin et comparées à un agent de contraste commercial à base d'oxyde de fer. Les nanohybrides étudiés n'ont pas présenté de cytotoxicité et ont développé des pouvoirs contrastants comparables à l'agent commercial. La biodistribution hépatique des nanoparticules couplées au mPEG-Si a été retardée de plus de 3 heures ouvrant la voie à des détections spécifiques.
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Tansik, Gulistan. "Synthesis Of Poly(dl-lactic-co-glycolic Acid) Coated Magnetic Nanoparticles For Anti-cancer Drug Delivery." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614087/index.pdf.
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One of the main problems of current cancer chemotherapy is the lack of selectivity of anti-cancer drugs to tumor cells which leads to systemic toxicity and adverse side effects. In order to overcome these limitations, researches on controlled drug delivery systems have gained much attention. Nanoscale based drug delivery systems provide tumor targeting. Among many types of nanocarriers, superparamagnetic nanoparticles with their biocompatible polymer coatings can be targeted to an intented site by an external magnetic field. Thus, the drug can be carried to the targeted site safely.
The aim of this study is to prepare poly(dl-lactic-co-glycolic acid) (PLGA) coated magnetic nanoparticles and load anti-cancer drug, doxorubicin to them. For this purpose, magnetite (Fe3O4) iron oxide nanoparticles were synthesized as a magnetic core material (MNP) and then coated with oleic acid. Oleic acid coated MNP (OA-MNP) was encapsulated into PLGA. Effects of different OA-MNP/PLGA ratios on magnetite entrapment efficiency were investigated. Doxorubicin loaded magnetic polymeric nanoparticles (DOX-PLGA-MNP) were prepared. After the characterization of prepared nanoparticles, their cytotoxic effects on MCF-7 cell line were studied.
PLGA coated magnetic nanoparticles (PLGA-MNP) had a proper size and superparamagnetic character. The highest magnetite entrapment efficiency of PLGA-MNP was estimated as 63 % at 1:8 ratio. Cytotoxicity studies of PLGA-MNP did not indicate any notable cell death between the concentration ranges of 2 and 250 &mu<br>g ml-1. It was observed that DOX-PLGA-MNP showed significant cytotoxicity on MCF-7 cells compared to PLGA-MNP.
The results showed that prepared nanoparticles have desired size and superparamagnetic characteristics without serious toxic effects on cells. These nanoparticles may be suitable for targeted drug delivery applications. The findings obtained from drug studies may contribute to further work.
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Gebara, Renan Castelhano. "Toxicidade de nanopartículas de óxido de ferro (Fe3O4) para o cladócero tropical Ceriodaphnia silvestrii." Universidade Federal de São Carlos, 2017. https://repositorio.ufscar.br/handle/ufscar/9045.
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Previous issue date: 2017-03-02<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>Nanoparticles (NPs) have been produced on a large scale worldwide for various consumer purposes such as the production of cosmetics, sunscreen, biosensors, human prosthetics and cancer therapy. However, due to its large production, NPs can have water bodies as final destination, where current studies addressing these compounds are not sufficient to estimate the threat that these substances could cause to aquatic organisms. Chronic studies with nano-Fe3O4 are scarce and, to the best of our knowledge, inexistent regarding tropical zooplankton species, although chronic studies are of great importance to predict the effects of the substances because they analyses great part of this organisms life cycle. At present study, we investigated nanoparticles of Fe3O4, to the tropical cladoceran Ceriodaphnia silvestrii using acute toxicity tests (0.00; 0.01; 0.10; 1.00; 10.00 and 100.00 mg L-1) during 48h, and chronic toxicity tests (0.00; 3.125; 6.25; 12.50; 25.00 and 50.00 mg L-1) during 14 days. Characterization of NPs in the exposure medium revealed that they experienced agglomeration and aggregation on a micrometer scale. Results showed non-toxicity of nano-Fe3O4 after 48h of acute exposure (EC5048h > 100.00 mg L-1). ). In chronic tests, treatment of 50 mg L-1 caused significant inhibition of growth and reproduction, affecting the maximum length (inhibited 12.71%), accumulated number of eggs (reduction of 51.99%) and neonates (decrease of 61.37%) per female (Dunnett’s test, p < 0.05). We concluded that nano-Fe3O4, in the 14th day, was toxic to C. silvestrii only at the highest concentration tested (50.00 mg L-1) during this chronic exposure.. The use of nano-Fe3O4 in aquatic environments could be considered safe to this species in concentrations up to 25.00 mg L-1, according to the parameters evaluated.<br>As nanopartículas (NPs) têm sido amplamente produzidas em larga escala para vários propósitos tais como: produção de cosméticos, protetores solares, biosensores, próteses humanas e tratamento do câncer. No entanto, devido à ampla produção, eventualmente as NPs podem encontrar seu destino final nos corpos d’água, onde os estudos relativos à presença dessas substâncias muitas vezes não são suficientes para estimar os efeitos que as mesmas poderiam causar nos organismos aquáticos. Estudos de toxicidade crônica com nanopartículas de óxido de ferro (nano-Fe3O4) são escassos e, até onde sabemos, inexistentes para cladóceros tropicais, embora avaliações crônicas sejam de grande importância para predição dos efeitos de substâncias, pois abrangem grande parte do ciclo de vida dos organismos. No presente estudo, foram estudadas nanopartículas de Fe3O4 para cladócero neotropical Ceriodaphnia silvestrii, por meio de testes de toxicidade aguda (0,00; 0,01; 0,10; 1,00; 10,00 e 100,00 mg L-1), durante 48 horas, e crônica (0,00; 3,125; 6,25; 12,50; 25,00 e 50,00 mg L-1), durante 14 dias. A caracterização das NPs nos meios de exposição revelou que elas sofreram aglomeração e agregação em escalas micrométricas. Os resultados obtidos apontaram ausência de toxicidade aguda para as nano-Fe3O4 (CE(I)5048h > 100,00 mg L-1). Nos testes de toxicidade crônica, no tratamento de 50,00 mg L-1, houve inibição significativa no crescimento e reprodução, afetando o comprimento máximo (inibição de 12,71%) e o número acumulado de ovos (diminuição de 51,99%) e de neonatas (diminuição de 61,37%) produzidos por fêmea (teste de Dunnett p < 0.05). Concluiu-se que as nano-Fe3O4 apresentaram efeitos crônicos, no 14º dia, para o cladócero C. silvestrii somente na maior concentração avaliada (50,00 mg L-1). O uso de nano-Fe3O4 em ambientes aquáticos pode ser considerado seguro para esta espécie de cladócero tropical, com base nos parâmetros avaliados, até concentrações de 25,00 mg L-1.<br>CNPq: 132379/2015-5<br>FAPESP: 2014/14139-3<br>FAPESP: 2016/00753-7
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Pirani, Parisa. "Surface-Engineered Magnetic Nanoparticles for Sample Preparation and Analysis of Proteins and Peptides." ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/2012.
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Sample preparation as an essential step in mass spectrometry-based analysis, plays a critical role in proteomics studies. Magnetic nanoparticles (MNPs) have been widely used in protein and peptide sample preparation due to their magnetic properties, biocompatibility, easy synthesis and surface functionalization. MNPs loaded with analyte or analyte modification reagent can be easily separated from the reaction medium by an externally applied magnetic field. The small size of MNPs provides high analyte loading and extraction capacity. Additionally, MNP can be decorated with different functional groups to achieve selective modification or extraction of analyte. In this study we have utilized silica coated iron oxide magnetic nanoparticles (Fe3O4@SiO2 MNPs) for protein and peptide sample preparation.
Fluorescence-based methods were utilized for quantitative and qualitative characterization of N-hydrosucccinimidyl (NHS) ester groups on the surface of Fe3O4@SiO2 MNPs. Fluorophore Dansylcadaverine was conjugated to NHS ester functional groups. Fluorometric measurement of cleaved dansylcadaveine was employed to determine the number of NHS ester groups per MNPs that was found to be 2.6 × 102 and 3.4 × 103for 20 nm and 100 nm Fe3O4@SiO2 MNPrespectively. The efficiency of labeling native bovine serum albumin (BSA) by NHS ester coated Fe3O4@SiO2 MNPs was also explored in terms of maximizing the number of MNPs conjugated per BSA molecule or maximizing the number of BSA molecules conjugated per each MNP.
Lysine residues of apolipoprotein B-100 (apoB-100) on the surface of intact human low density lipoprotein (LDL) were labeled by NHS ester modified Fe3O4@SiO2 MNPs in aqueous solvents at room temperature. The MNP labeledapoB-100 was treated by SDS to remove lipids and then digested using trypsin. Tryptic peptides were eluted from MNPs by cleaving disulfide linkage between labeled peptides and MNPs. LC-MS/MS analysis found 28 peptides containing labeled lysine residues. These lysine residues should be on the solvent exposed surface of LDL since the large size of MNPs prevents contact of the labeling reagent to those lysines embedded inside the structure of LDL.
TCEP- immobilized Fe3O4@SiO2MNPs were fabricated and utilized for reduction of disulfide bonds in bovine pancreas insulin and two different cyclic peptides. Disulfide bonds were efficiently cleaved at room temperature in both organic and aqueous solvents confirmed by LC-MS/MS analysis of reduced/alkylated protein and peptides. Disulfide reduction and alkylation reactions was performed in one step and the reducing agent was simply separated from peptide and protein solution by magnetic separation.
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Orozco, Henao Juan Manuel 1989. "Efeitos de tamanho e geometria nas propriedades magnéticas e de hipertermia magnética em nanopartículas de Fe3O4." [s.n.], 2016. http://repositorio.unicamp.br/jspui/handle/REPOSIP/305751.
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Orientador: Marcelo Knobel<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin<br>Made available in DSpace on 2018-08-30T18:13:51Z (GMT). No. of bitstreams: 1
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Previous issue date: 2016<br>Resumo: Nanopartículas de magnetita com diâmetros entre 5nm e 19nm sintetizadas mediante um método de decomposição térmica são apresentadas. A caracterização estrutural é feita usando diferentes técnicas experimentais como a microscopia eletrônica de transmissão (TEM), difração de raios-X e espalhamento de raios-X a baixos ângulos (SAXS) de onde são obtidos os tamanhos e a forma das nanopartículas. As propriedades magnéticas e de magneto-hipertermia das nanopartículas são estudadas para diferentes parâmetros de produção como concentração dos surfactantes, temperaturas de refluxo e atmostfera de crescimento. A dependência com a temperatura das propriedades magnéticas são analisadas dentro do marco do modelo usual do superparamagnetismo e o modelo de interação superparamagnética (ISP), de onde os parâmetros magnéticos dependentes do tamanho como anisotropia magnética (1.06x10^4 J/m^3 até 9.91x10^4 J/m^3), momento magnético por partícula (2618?B até 11500?B), temperatura de bloqueio (18K até mais de 300K) e energia de ineração dipolar magnética (0.55x10^-21 J até 5.5x10^-21 J) são inferidos. Os resultados de magneto-hipertermia foram obtidos mediante a medição da resposta térmica das nanopartículas de magnetita suspendidas em tolueno. Valores da taxa de absorção específica (SAR) são calculados experimental e teoricamente utilizando a teoria de resposta linear para um sistema superparamagnético não interagente. Valores de SAR entre 3.0W/g e 40.3W/g e a sua dependência com a frequência e o campo aplicado são apresentados. Como resultado interessante, a resposta de magneto-hipertermia para as nanopartículas de 19nm preparadas na presença de oxigênio e mais de 10 vezes maior do que nanopartículas similares mas obtidas na ausência da atmosfera de oxigênio. Também é destacada a possibilidade de prever a resposta de magneto-hipertermia num sistema de nanopartículas magnéticas mediante a obtenção dos parâmetros de caracterização magnetica e estrutural<br>Abstract: Magnetite nanoparticles with diameters between 5nm and 19nm synthesized by means of a thermal decomposition method are presented. Structural characterization is made by different experimental techniques such as transmission electron microscopy (TEM), X-ray diffraction and Small Angle X-ray Scattering (SAXS) from where nanoparticles size and shape are obtained. Magnetic and magneto-hyperthermia properties of the nanoparticles are studied for different production parameters, such as surfactant concentrations, refluxing temperature and growth atmosphere. Temperature dependence of the magnetic properties are analyzed in the framework of the standard superparamagnetism model and the interacting superparamagnetic model (ISP), from where size dependent magnetic parameters for each sample such as anisotropy (1.06×10^4 J/m^3 to 9.91x10^4 J/m^3) magnetic moment per particle (2618?B to 11500?B), blocking temperature (18K to above 300K) and magnetic dipolar interaction energy on dried nanoparticle samples (0.55 × 10^?21 J to 5.5 × 10^?21 J) are inferred. Magneto-hyperthermia results are obtained by measuring the thermal response of magnetite nanoparticles dissolved in toluene. Specific absorption rate (SAR) values are theoretically and experimentally calculated by means of a linear response theory approach of a non-interacting superparamagnetic system. SAR values between 5.8W/g and 40.3W/g are reported; interestingly, the magneto-hyperthermia response for 19nm nanoparticles prepared in presence of an oxygen atmosphere is more than 10 times larger than similar particles obtained in absence of oxygen atmosphere. Also it is important to highlight the possibility to obtain the magneto-hyperthermia behavior of a magnetic nanoparticles system by knowing a priori its structural and magnetic characterization parameters<br>Mestrado<br>Física<br>Mestre em Física<br>1247647/2013<br>CAPES
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Busse, Marta Julia. "Bionanocomposites of Fe3O4/SiO2 and alginate for magnetic removal of Cr(III) species from water." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14196.
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Mestrado em Química<br>The aim of the present work was to study the removal of Cr (III) species from
aqueous solutions by adsorption process, using magnetic nanoparticles
functionalized with amine groups and with the polysaccharide alginate.
Heavy metal pollution is serious environmental and public health problem
worldwide. Chromium is one of the most toxic metal endangering human life.
Cr(III) is often used in industry which caused water pollution. Therefore,
increased interest by the researchers to employ nanomaterials for the removal
contamination and explore adsorbents to replace expensive materials,
particularly low-cost raw materials such as, residual polymers materials or
agricultural by-products.
The work included the preparation of magnetic nanoparticles, coating them with
amorphous silica shell functionalized with amine groups and the covalent
attachment of alginate to the magnetic nanoparticle. The properties of the
nanoparticles were assessed by a number of experimental techniques namely
x-ray diffraction, infrared spectroscopy, elemental analysis, thermogravimetry
and zeta potential measurements.
Silica coated magnetic nanoparticles functionalized with amine groups were
investigated for the uptake of Cr(III)/EDTA complexes from water, while the
nanoparticles attached to the alginate molecules were tested for the removal of
aqueous Cr(III) ions. The kinetic results were fitted to models of pseudo first
and pseudo second order and the equilibrium adsorption results were adjusted
to suitable isotherm models such as Langmuir and Freundlich.
The composite nanoparticles revealed affinity to the Cr(III) species. Due to its
properties, this new composite nanoparticles may find interesting applications
in purification of water.<br>O objectivo do presente trabalho foi o de estudar a eliminação de Cr (III), a
partir de soluções aquosas, por processo de adsorção, utilizando
nanopartículas magnéticas funcionalizadas com grupos amina e com o
polissacarídeo alginato.
A poluição causada por metais pesados está na base de graves problemas de
saúde pública e ambientais em todo o mundo. O crómio é um dos metais mais
tóxicos, pondo em perigo a vida humana. O Cr (III) é frequentemente usado na
indústria, causando a poluição da água. Por esta razão, aumentou o interesse
dos investigadores na utilização de nanomateriais para a remoção de
poluentes e no estudo de adsorventes para substituir materiais caros,
nomeadamente matérias-primas de baixo custo, tais como, materiais
provenientes de polímeros residuais ou subprodutos agrícolas.
Este trabalho incluiu a preparação de nanopartículas magnéticas, o seu
revestimento com uma capa de sílica amorfa funcionalizada com grupos de
amina e a ligação covalente do alginato à nanopartícula magnética. As
propriedades das nanopartículas foram avaliadas utilizando várias técnicas
experimentais nomeadamente difracção de raios-X, espectroscopia de
infravermelho, análise elementar, termogravimetria e medições do potencial
zeta.
As nanopartículas magnéticas revestidas com sílica e funcionalizadas com
grupos de amina foram investigadas para a adsorção de Cr (III) / complexos
de EDTA de águas, enquanto que as nanopartículas ligadas às moléculas de
alginato foram testadas para a remoção de iões Cr (III) em meio aquoso. Os
resultados de cinética foram ajustados aos modelos de pseudo-primeira e
pseudo-segunda ordem, e os resultados de equilíbrio de adsorção foram
ajustados aos modelos adequados, tais como a isotérmica de Langmuir e a de
Freundlich.
As nanopartículas compósitas revelaram ter afinidade para as espécies de Cr
(III). Devido às suas propriedades, estas nova nanopartículas compósitas
podem encontrar aplicações interessantes na purificação de águas.
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Fang, Mei. "3D Magnetic Photonic Crystals : Synthesis and Characterization." Licentiate thesis, KTH, Materials Science and Engineering, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11983.
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Zhang, Yu. "Photothermal effect of PS coated Fe3O4 nanoparticles via near-infrared laser and effect of mimic body tissue depth on hyperthermic ablation of MDA-MB-231." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1445343075.
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Strandqvist, Carl. "The Functionalization of Epitaxial Graphene on SiC with Nanoparticles towards Biosensing Capabilities." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-120502.
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Graphene has been shown to be very powerful as a transducer in many biosensor applications due to its high sensitivity. This enables smaller surfaces and therefore less material consumption when producing sensors and concequently cheaper and more portable sensors compared to the commercially available sensors today. The electrical properties of graphene are very sensitive to gas exposure why presence of molecules or small changes in concentration could easily be detected when using graphene as a sensing layer. Graphene is sensitive towards many molecules and in order to detect and possibly identify gas molecules the surface needs to be functionalized. The intention of this project was to use nanoparticles (NPs) to further increase sensitivity and specificity towards selected molecules and also enable biofunctionalization of the NPs, and by that tune the electrical properties of the graphene. This study proposes the use of Fe3O4 and TiO2 NPs to enable sensitive detection of volatile gases and possibly further functionalization of the NPs using biomolecules as a detecting agent in a liquid-phasebiosensor application. The interaction between graphene and NPs have been investigated using several surface charactarization methods and electrical measurements for detection of gaseous molecules and also molecules in a liquid solution. The characterizing methods used are XPS, AFM with surface-potential mapping and Raman spectroscopy with reflectance mapping in order to investigate the NPs interaction with the graphene surface. Sensors where manufactured for gas-phase detection of CO, formaldehyde, benzene and NH3 specifically and display differences in sensitivity and behavior of the Fe3O4 and TiO2 NPs respectively. For liquid measurements the difference in behavior in two buffers was investigated using an in-house flow-cell setup. The surface charecterizing measurements indicated that just a small difference could be found between the two NPs, however a significant change in sensor response could be detected as a function of coverage. The liquid and gas-phase measurements rendered information on differences in sensitivity between the NPs and between analytes where TiO2 showed a higher level of sensitivity towards most of the gases investigated. Both Fe3O4 and TiO2 NP coated graphene showed capability to detect formaldehyde and benzene down to 50 ppb and 5 ppb respectively. The sensitive gas detection could help protecting individuals being exposed to a hazardous level of volatile gases if concentrations increase rapidly or at a long term exposure with lower concentrations, improving saftey and health where these gases are present.
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Netočný, Martin. "Řízení struktury polymerního nanokompozitu pomocí magnetického pole." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-295721.
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This work is dealing with usage of external magnetic field for controlled orientation of structures assembled from magnetic Fe3O4 nanoparticles in PMMA matrix processed via solvent casting method and further study of these created anisotropic structures and their influence on mechanical properties of composite material.
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Miyashiro, Carolina Sayury. "Desenvolvimento e aplicação de biocoagulante magnético Fe3O4-MO para remoção do corante reativo preto 5 em meio aquoso sintético e efluente real têxtil." Universidade Estadual do Oeste do Paraná, 2017. http://tede.unioeste.br/handle/tede/3575.
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Previous issue date: 2017-12-11<br>Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq<br>A magnetic biocoagulant (Fe3O4-MO) was produced by the association of nanoparticles of iron oxide (Fe3O4) and Moringa Oleífera Lam (MO) extract in different concentrations (0.5%, 1% and 2%), aiming to evaluate its performance in removal of the reactive dye black 5 (RP5) in aqueous medium (synthetic waste water) and real textile effluent. The MO protein was extracted with saline solution and the nanoparticles were synthesized by the coprecipitation method. The biocoagulant was characterized by X-ray diffractometry (XRD), vibration magnetometry, Fourier Infrared Transformer (FTIR) spectroscopy, scanning electron microscopy with X-ray energy dispersion spectroscopy (SEM / EDS) and transmission electron microscopy (MET). For the coagulation / flocculation / sedimentation process (C/F/S), the operational parameters studied were sedimentation time, biocoagulant concentration and pH. The efficiency of the C/F/S process was determined by the analysis of the apparent color, absorbance, zeta potential and total organic carbon (TOC). After determining the best conditions (concentration of 0.5% MO, dosage of 100 mg L-1 and pH 7) of the C/F/S process, sedimentation kinetic studies for synthetic wastewater (ARS), real effluent (ERT), both with and without magnetic field and the sludge recovered and regenerated with the saline extract of MO (with magnetic field). At the 100 mgL-1 dosage of magnetic biocoagulant at a concentration of 0.5% MO saline, 89% apparent color removals were obtained in the time of 20 min. The C / F / S process shows dependence on the pH of the reaction medium, because at pH 7 color removal values of 83% and 84% were obtained in reaction time 20 and 40 min, respectively.<br>Um biocoagulante (Fe3O4-MO) magnético foi produzido pela associação de nanopartículas de óxido ferro (Fe3O4) e extrato de Moringa Oleífera Lam (MO) em diferentes concentrações (0,5%, 1% e 2%), para avaliar sua performance na remoção do corante reativo preto 5 (RP5) em meio aquoso (água residuária sintética) e efluente real têxtil. A proteína da MO foi extraída com solução salina e as nanopartículas foram sintetizadas pelo método de coprecipitação. O biocoagulante foi caracterizado por difratometria de raio-X (DRX), magnetometria vibratória, spectroscopia por transformada de Fourier (FTIR), microscopia eletrônica de varredura com espectroscopia por dispersão de energia de Raios-X (MEV/EDS) e microscopia eletrônica de transmissão (MET). Para o processo de coagulação/floculação/sedimentação (C/F/S) os parâmetros operacionais estudados foram tempo de sedimentação, concentração do biocoagulante e pH. A eficiência do processo C/F/S foi determinada pela análise da cor aparente, absorbância, potencial zeta e carbono orgânico total (COT). Após determinar as melhores condições (concentração de MO 0,5%, dosagem de biocoagulante 100 mg L-1 e pH 7) do processo C/F/S, foram realizados estudos cinéticos de sedimentação para água residuária sintética (ARS), efluente real têxtil (ERT), ambos com e sem campo magnético e o lodo recuperado e regenerado com o extrato salino de MO (com campo magnético). Na dosagem 100 mgL-1 de biocoagulante magnético em concentração de 0,5% de solução salina de MO foram obtidos remoções de cor aparente 82% no tempo de 20 min. O processo C/F/S apresenta dependencia em relação ao pH do meio reacional, pois em pH 7 foram obtidos valores de remoção de cor de 83 % e 84 % em tempo de sedimentação 20 e 40 min., respectivamente. Demonstrando-se um materialpromissor na remoção de RP5 e no tratamento de ERT pois possui alta eficiência, preparo simples e condizentes com questões ambientais.
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Doddapaneni, Venkatesh. "On the polymer-based nanocomposites for electrical switching applications." Doctoral thesis, KTH, Tillämpad fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-202702.
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Recent research demonstrated that polymer based nanocomposites (PNCs) have been engineered in order to improve the arc interruption capability of the circuit breakers. PNCs are the combination of nano-sized inorganic nanoparticles (NPs) and polymers, opened up new developments in materials science and engineering applications. Inorganic NPs are selected based on their physical and chemical properties which could make multifunctional PNCs in order to interrupt the electrical arcs effectively. In particular, we presented the PNCs fabricated by using CuO, Fe3O4, ZnO and Au NPs in a poly (methyl methacrylate) (PMMA) matrix via in-situ polymerization method, recently developed method to avoid NPs agglomeration, leading to good spatial distribution in the polymer matrix. Thus, several samples with various wt% of NPs in PMMA matrix have been fabricated. These PNCs have been characterized in detail for the morphology of NPs, interaction between NPs and polymer matrix, and radiative/thermal energy absorption properties. In the next stage, PNCs are tested to determine their arc interruption performance and impact on the electrical arcs of current 1.6 kA generated using a specially designed test set-up. When PNCs interact with the electrical arcs, they generate ablation of chemical species towards core of the electrical arc, resulting in cooling-down the arc due to strong temperature and pressure gradient in the arc quenching domain. This thesis demonstrates for the first time that these engineered PNCs are easily processed, reproducible, and can be used to improve the arc interruption process in electrical switching applications.<br>Ny forskning har visat att polymerbaserade nanokompositer (PNCs) har utformats för att förbättra strömbrytares förmåga att undvika ljusbågar vid överslag. PNCs är en kombination av nanostora oorganiska nanopartiklar (NP) och polymerer, som har öppnat upp för ny utveckling inom materialvetenskap och tekniska tillämpningar. Oorganiska NP väljs baserat på deras fysikaliska och kemiska egenskaper som kan hjälpa PNCs att motverka elektriska ljusbågar effektivt. I synnerhet, presenterade vi PNCs tillverkade genom användning av CuO, Fe3O4, ZnO och Au NP i en poly (metylmetakrylat) (PMMA)-matris via in situ-polymerisationsmetod, nyligen utvecklad för att undvika NP-agglomerering, vilket leder till god rumslig fördelning i polymermatrisen. Därför har flera prover med olika vikt% av NP i PMMA-matris tillverkats. Dessa PNCs har utvärderats i detalj för NP-morfologi, interaktion mellan NP och polymermatris, och strålnings- och värmeenergiabsorption. I nästa skede testas PNCs för att bestämma deras förmåga att undvika ljusbågar och påverkan på de elektriska ljusbågarna av 1,6 kA strömstyrka, genererade med hjälp av en specialdesignad test-set-up. När PNCs interagerar med de elektriska ljusbågarna, genererar de ablation av kemiska ämnen mot kärnan i den elektriska ljusbågen, vilket resulterar i nedkylning av ljusbågen på grund av starka temperatur- och tryckgradienter i området. Denna avhandling visar för första gången att dessa konstruerade PNCs är lätta att framställa, reproducerbara, och kan användas för att förbättra avbrottsprocessen för ljusbågen i elektriska kopplingstillämpningar.<br><p>QC 20170303</p>
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BERARDI, GINEVRA. "Multitasking Fe3O4@Cu@Au and Fe3O4@SiO2 nanoparticles for biomedical applications." Doctoral thesis, 2018. http://hdl.handle.net/11573/1215256.
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Tra i nanomateriali utili in ambito biomedico, le nanoparticelle di magnetite offrono grandi vantaggi sia in campo diagnostico che terapeutico, permettendo di combinare le loro peculiari proprietà magnetiche con le note proprietà chimico fisiche che caratterizzano le nanoparticelle. Realizzando una struttura core-shell e funzionalizzando la superficie della nanoparticella con sostanze biologicamente o farmacologicamente attive, è possibile, da un lato, conservare le proprietà superparamagnetiche del nucleo e, dall'altro, ottenere nanosistemi multifunzionali più selettivi e/o efficaci nei confronti dei target biologici prescelti. Lo scopo di questa tesi ha riguardato, quindi, la progettazione e la realizzazione di nanosistemi basati su nanoparticelle core-shell costituite da Fe3O4@Cu@Au o Fe3O4@SiO2 utilizzabili per diverse applicazioni biomediche. La sintesi delle nanoparticelle è stata effettuata utilizzando reagenti biocompatibili mentre una approfondita caratterizzazione chimico-fisica dei nanosistemi è stata ottenuta tramite l'analisi con differenti tecniche microscopiche e spettroscopiche. Attraverso esperimenti biologici in vitro, è stata valutata l' efficacia terapeutica e/o l' internalizzazione in cellule immunitarie di nanosistemi opportunamente funzionalizzati con farmaci chemioterapici, macromolecole biologiche o metaboliti secondari con attivià antibiotica. Infine, nanoparticelle funzionalizzate con specifici anticorpi sono state utilizzate per lo sviluppo di strumenti diagnostici per la rivelazione di neurotrasmettitori in vitro.
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Prakash, Swayam, and Supriya Mishra. "Graphene-Fe3O4-TiO2 ternary composite: an efficient visible light catalyst for the removal of organic pollutants." Thesis, 2014. http://ethesis.nitrkl.ac.in/6505/1/E-21.pdf.
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A facile synthesis technique was employed for producing magnetic graphene-TiO2 photocatalyst (GO-Fe3O4-TiO2). The synthesis method involves combination of sol-gel and assembling processes. The magnetic composite was characterized by, XRD, SEM, FESEM and UV-DRS analysis. The as synthesized material showed higher photocatalytic activity towards methylene blue (MB) degradation as compared with that of pure TiO2 and GO-Fe3O4 nanocomposite. Magnetic property of the nanocomposite defines it to be easily separable for repeated applications. These attractive physical properties and efficient photocatalytic activity quote GO-Fe3O4-TiO2 nanocomposite as a promising photocatalyst under sunlight for practical use in wastewater treatment to control water pollution.
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Huang, Kuo-Chan, and 黃國展. "Synthesis of magnetic core–shell Fe3O4–Au nanoparticle for MRI/CT Hybrid Imaging Application." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/c53g6b.
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碩士<br>慈濟科技大學<br>放射醫學科學研究所<br>105<br>Abstract
To date, a wide variety of magnetic nanoparticles have been produced, differing in size and type of coating material,including dextran, citrate, starch,albumin, silicones and polyethyleneglycol. The diversified usage of magnetic nanoparticles were particularly in the biomedical applications including MRI contrast agent, hyperthermia, PET-MR contrast agent and drug delivery. Among the developed nanoparticles systems,superparamagnetic iron oxide nanoparticles have been extensively explored as a negative contrast agent for T2-weighted magnetic resonance imaging applications.
In this study, we used the chemical co-precipitation method to prepare the superparamagnetic iron oxide nanoparticles, and coated with: good biocompatibility, can reduce the biological toxicity and make the nanoparticles more stable in human body and chemically stable effect. The selected of low molecular weights dextran as a magnetic nanoparticles interface active agent, and combined with the gold ion (of Au3+) onto the iron oxide nanoparticle’s surfaces via iterative hydroxylamine seeding, the combination of the two differentiation magnetic pole has potential for use in MRI/CT contrast agent applications.
The MR and CT imaging data reveal that the formed Fe3O4@Au nanohybride have a relatively high r2 relaxivity (42.2s-1) and good X-ray attenuation property, which enables their uses as contrast agents for MR and CT imaging of water phantom. The Fe3O4@Au nanohybride developed via the co-precipitation approach may have promising potential for the dual-mode MR/CT.
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Yang, Ya-Han, and 楊雅涵. "Morphological effect of Au-Fe3O4 nanoparticle on T2 relaxation and its sensing effect of tau protein." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/13034669694476621313.
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碩士<br>國立清華大學<br>生醫工程與環境科學系<br>102<br>Nanoparticles have been used in biomedical application extensively. For iron oxide nanoparticles, known as SPIO or USPIO, it has applied to be a negative contrast agent to investigate the reticuloendothelial system such as liver, spleen and lymph nodes in MRI. For gold nanoparticles, it had been used for the optical imaging or color sensing. The combined of gold and iron oxide nanoparticles, Au-Fe3O4 had been synthesized as dumbbell-like (DBNPs) and flower-like (FLNPs) composites. The heterostructures of Fe3O4 have not been analyzed the ability of contrast by the morphological effect. In this study, we had evaluated the morphological effect on T2 relaxation.
In biomedical application, we had used DBNPs to reaction with tau protein, related with Alzheimer’s disease. Tau protein is the normal component in structure in the neuron cell. In unknown pathogenesis, tau protein release to cerebral spinal fluid (CSF) and the neuron cell would breakdown. The disease severity is highly correlated with concentration of tau protein in CSF. The tau protein sensing at the prophase of disease is very important for prevent medicine. Even though the tau protein sensing was limited by the sensor design in this study, the sensor could be revising at the future work.
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Ho, Cheng-Yu, and 何承育. "Spin injection from Ni thin film and Fe3O4 nanoparticle into InGaN/GaN nanorod light-emitting diode." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/68035608835385142199.
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碩士<br>國立臺灣大學<br>應用物理所<br>100<br>The motivation of this thesis is to compare the performance of the degree of circularly polarized light between conventional thin film spin-LED and nanorod spin-LED. In our experiment, we compare the degree of circularly polarized light for the thin film and nanorod spin-LEDs, which is composed of InGaN/GaN multiple quantum wells, under an external magnetic field by photoluminescence and electroluminescence. We also deposit the Fe3O4 nanoparticles into the space between nanorods in order to enhance the degree of circularly polarized light arising from nanorod spin-LED.
The quantum confined stark effect will gradually vanish and confined potential will become more symmetric as the thin film multiple quantum wells are etched into the nanorod structure. Thus the spin coherent time will become longer in quantum well. In addition, the efficiency of spin valve will increase after the deposition of Fe3O4 nanoparticles. Due to the increment for both the spin coherence time and efficiency of spin valve, our results show that the degree of circularly polarized light of the nanorod spin-LED with Fe3O4 nanoparticles under low external magnetic field and room temperature can be more than 10%. Its excellence performance and practical working condition make nanorod spin-LED becomes a potential spin device.
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Venkatesha, N. "Nanoparticles for Bio-Imaging : Magnetic Resonance Imaging and Fluorescence Imaging." Thesis, 2015. http://etd.iisc.ac.in/handle/2005/3860.
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This thesis provides several nanomaterial systems that can be used as contrast agents in magnetic resonance imaging (MRI) and for optical fluorescence imaging. Nanoparticle systems described in this thesis fall under three categories: (a) graphene oxide-nanoparticle composites for MRI contrast agent application, (b) core-shell nanoparticles for MRI contrast agent
application and (c) nanoparticle systems for both MRI and optical fluorescence imaging. In the case of graphene oxide based nano-composites, the following observations were made: (i) in the case of graphene oxide-Fe3O4 nanoparticle composite, it was observed that high extent of oxidation of the graphene oxide and large spacing between the graphene oxide sheets containing Fe3O4 nanoparticles provides the optimum structure for yielding a very high transverse proton relaxivity value, (ii) in the case of graphene oxide-Gd2O3 nanoparticle composite, it was observed that this composite exhibits high value for both longitudinal and transverse relaxivity
values making it a potential materials for multi-contrast study of pathologies with a single agent,
(iii) in the case of graphene oxide-CoFe2O4 nanoparticle composites, it was observed that an increase in the reflux time of the reaction mixture containing this composite led to appreciable variations in the proton relaxivity values. Transverse relaxivity value of the water protons increased monotonically with increase in the reflux time. Whereas, the longitudinal relaxivity
value initially increased and then decreased with increase in the reflux time. In the case of coreshell nanoparticles for MRI contrast agent application two different core-shell systems were investigated. They are MnFe2O3-Fe3O4 core-shell nanoparticles and CoFe2O4-MnFe2O4 coreshell nanoparticles. Investigations of both the core-shell nanoparticle systems revealed that the
proton relaxivity value obtained in the dispersion of the core-shell nanoparticles was considerably greater than the proton relaxivity value obtained in the presence of single phase nanoparticles of the core and shell phases. Very high value of transverse relaxivity in the case core-shell nanoparticles was due to the large magnetic inhomogeneity created by the core-shell
nanoparticles in the water medium surrounding it. In the case of nanoparticle systems for both MRI and optical fluorescence imaging, two different systems were investigated. They were CoFe2O4-ZnO core-shell nanoparticles and Gd doped ZnS nanoparticles [Zn1-xGdxS, x= 0.1, 0.2 and 0.3] formed on graphene oxide sheets or coated with chitosan. In the case of CoFe2O4-ZnO core-shell nanoparticles it was observed that fluorescent CoFe2O4-ZnO core-shell nanoparticles with the unique geometry in which CoFe2O4 ferrite nanoparticles agglomerates were present
within larger sized hollow ZnO capsules yields very high value of transverse proton relaxivity when compared to the proton relaxivity value exhibited by the individual CoFe2O4-ZnO coreshell nanoparticles. In the case of Gd doped ZnS nanoparticles, two different systems were synthesized and the values of the longitudinal and transverse proton relaxivity obtained were compared. These systems were (i) graphene oxide- Zn1-xGdxS (x= 0.1, 0.2 and 0.3) nanoparticle
composites and (ii) chitosan coated Zn1-xGdxS (x= 0.1, 0.2 and 0.3) nanoparticles. It was
observed that Gd doped ZnS nanoparticles in both cases exhibit both longitudinal and transverse relaxivity values. The relaxivity values showed a clear dependence on the composition of the nanoparticles and the nanoparticle environment (presence and absence of graphene oxide). It was
also observed that Gd doped ZnS nanoparticle can be used for florescence imaging.
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Venkatesha, N. "Nanoparticles for Bio-Imaging : Magnetic Resonance Imaging and Fluorescence Imaging." Thesis, 2015. http://etd.iisc.ernet.in/2005/3860.
Full textAbstract:
This thesis provides several nanomaterial systems that can be used as contrast agents in magnetic resonance imaging (MRI) and for optical fluorescence imaging. Nanoparticle systems described in this thesis fall under three categories: (a) graphene oxide-nanoparticle composites for MRI contrast agent application, (b) core-shell nanoparticles for MRI contrast agent
application and (c) nanoparticle systems for both MRI and optical fluorescence imaging. In the case of graphene oxide based nano-composites, the following observations were made: (i) in the case of graphene oxide-Fe3O4 nanoparticle composite, it was observed that high extent of oxidation of the graphene oxide and large spacing between the graphene oxide sheets containing Fe3O4 nanoparticles provides the optimum structure for yielding a very high transverse proton relaxivity value, (ii) in the case of graphene oxide-Gd2O3 nanoparticle composite, it was observed that this composite exhibits high value for both longitudinal and transverse relaxivity
values making it a potential materials for multi-contrast study of pathologies with a single agent,
(iii) in the case of graphene oxide-CoFe2O4 nanoparticle composites, it was observed that an increase in the reflux time of the reaction mixture containing this composite led to appreciable variations in the proton relaxivity values. Transverse relaxivity value of the water protons increased monotonically with increase in the reflux time. Whereas, the longitudinal relaxivity
value initially increased and then decreased with increase in the reflux time. In the case of coreshell nanoparticles for MRI contrast agent application two different core-shell systems were investigated. They are MnFe2O3-Fe3O4 core-shell nanoparticles and CoFe2O4-MnFe2O4 coreshell nanoparticles. Investigations of both the core-shell nanoparticle systems revealed that the
proton relaxivity value obtained in the dispersion of the core-shell nanoparticles was considerably greater than the proton relaxivity value obtained in the presence of single phase nanoparticles of the core and shell phases. Very high value of transverse relaxivity in the case core-shell nanoparticles was due to the large magnetic inhomogeneity created by the core-shell
nanoparticles in the water medium surrounding it. In the case of nanoparticle systems for both MRI and optical fluorescence imaging, two different systems were investigated. They were CoFe2O4-ZnO core-shell nanoparticles and Gd doped ZnS nanoparticles [Zn1-xGdxS, x= 0.1, 0.2 and 0.3] formed on graphene oxide sheets or coated with chitosan. In the case of CoFe2O4-ZnO core-shell nanoparticles it was observed that fluorescent CoFe2O4-ZnO core-shell nanoparticles with the unique geometry in which CoFe2O4 ferrite nanoparticles agglomerates were present
within larger sized hollow ZnO capsules yields very high value of transverse proton relaxivity when compared to the proton relaxivity value exhibited by the individual CoFe2O4-ZnO coreshell nanoparticles. In the case of Gd doped ZnS nanoparticles, two different systems were synthesized and the values of the longitudinal and transverse proton relaxivity obtained were compared. These systems were (i) graphene oxide- Zn1-xGdxS (x= 0.1, 0.2 and 0.3) nanoparticle
composites and (ii) chitosan coated Zn1-xGdxS (x= 0.1, 0.2 and 0.3) nanoparticles. It was
observed that Gd doped ZnS nanoparticles in both cases exhibit both longitudinal and transverse relaxivity values. The relaxivity values showed a clear dependence on the composition of the nanoparticles and the nanoparticle environment (presence and absence of graphene oxide). It was
also observed that Gd doped ZnS nanoparticle can be used for florescence imaging.
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CHANG, HAO-MING, and 張浩銘. "Activity enhancement of Fe3O4/SiO2 nanoparticle immobilized cellulase with glutaraldehyde and co-culture with Clostridium sp. TCW1 for biohydrogen production from cellulase." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/33444401285538058847.
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碩士<br>東海大學<br>環境科學與工程學系<br>104<br>Cellulose is the most abundant organic material in the world. Many municipal solid wastes or agricultural wastes contain a great amount of cellulose. Use of these cellulosic wastes to produce bio-hydrogen not only remove these wastes but also reduce the cost of raw materials from bio-hydrogen production. Cellulases catalyse the hydrolysis of cellulose and convert cellulose into cellobiose, glucose or other sugar. Due to the high price and solubility, cellulase is hard to recover from the substrate mixture after reaction for reuse. Therefore it is critical to find more techno-economic methods to improve the economics of cellulase utilization. Magnetic nanoparticles provide advantages as the supporting material for enzyme immobilization over traditional materials such as low cytotoxicity, large specific surface area and easy separation from reaction mixture by magnetic field. This study immobilized commercial cellulase from Trichoderma reesi on the Fe3O4/SiO2 magnetic nanoparticles by covalent binding via glutaraldehyde. The optimal cellulase immobilization condition and reaction activity of immobilized enzyme have been investigated. Finally immobilized cellulase was co-cultured with a hydrogen-producing pure culture Clostridium sp. TCW1 to investigate hydrogen production yield. From these results, it can be concluded that the immobilization of cellulase on magnetic Fe3O4/SiO2 nanoparticle with covalent binding via glutaraldehyde is a suitable method to significantly improve stability and reusability of cellulase. When co-cultured with Clostridium sp. TCW1, immobilized cellulase can improve hydrogen production yield from cellulase.
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Sung, Ti-Wen, and 宋狄文. "Synthesis and Magnetic Property of Monodisperse Fe3O4 Nanoparticles." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/15500989874650386343.
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碩士<br>遠東技術學院<br>機械研究所<br>93<br>This study is about the synthesis of Fe3O4 nanoparticles with precisely controlled sizes and size distributions. The precursors are oxygen-containing organic materials such as Fe(acac)3 or inorganic materials such as FeO(OH), which are decomposed in high-boiling point solvents to provide the monodispersed Fe3O4 nanoparticles. Particle diameters can be tuned from 4 to 20 nm by varying reaction conditions or by seed-mediated growth methods. Fe3O4 nanoparticles are synthesized with narrow size distributions (σ ~ 5 to 10%). The size of nanoparticles are mainly controlled by the variety of solvents with different boiling point and the iron-reactant/surfactant mole ratios.
The research is characterized by dynamic light scattering, powder X-ray diffraction, vibrating sample magnetometer and transmission electron microscopy.
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Ho, Chien-Hsin, and 何建新. "Shape-controlled Synthesis, Characterization, and Applications of Fe3O4 and FePt@Fe3O4 Core-shell Magnetic Nanoparticles." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/00723633832958956225.
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博士<br>國立清華大學<br>材料科學工程學系<br>98<br>摘要
本論文主要著重於四氧化三鐵和鐵鉑-四氧化三鐵核殼結構磁性奈米微粒之合成、形狀控制、鑑定、與其應用之研究。
首先，我們利用高溫注入前驅物的方法來製備四氧化三鐵的奈米微粒，注射時的反應溶液溫度為290 °C。我們發現溶液中鐵單體的濃度會影響著四氧化三鐵奈米微粒的形狀。當前驅物注射速度只有10 mL/h時，所還原出的有限鐵單體將優先成長於具有較高能量的晶面，而造成具有最低能量的{100}晶面變成主要外露面，最終得到立方體形的奈米微粒。然而，當注射速度增加到20 mL/h時，增加的鐵單體濃度會改變各主要晶面的相對成長速率。因此原本具有第二低能量的{110}晶面，也和{100}晶面一樣變成了主要外露面之一，最後形成了削菱截角立方體(Rhombicuboctahedron)。在我們的實驗中，這兩種四氧化三鐵奈米微粒的粒徑大約都在16奈米左右，並且都可以在TEM銅網上和矽基板上自組裝成具有優選晶體方向的奈米微粒超晶格結構。
第二部分的研究主要是製備具由核殼結構的鐵鉑-四氧化三鐵奈米立方體。我們利用上述之高溫注入前驅物的方法搭配晶種成長法，來製備具有球形鐵鉑核和立方體形四氧化三鐵殼的複合式磁性奈米微粒。此複合式奈米微粒的最終形狀主要取決於四氧化三鐵殼的成長條件。並且經由HRTEM的分析可得知，鐵鉑核和四氧化三鐵殼並不需具備磊晶成長關係，此結果表示內核的材料並不需要具備與外殼四氧化三鐵相近之晶體常數。因此，不同材料的核可被選用來製備具有核殼結構的四氧化三鐵奈米立方體，以增進其應用價值。
最後一部分則是探討四氧化三鐵和鐵鉑-四氧化三鐵奈米立方體的特性和前瞻應用。我們利用XMCD來量測鐵離子在四氧化三鐵內不同位置的分佈情形。在立方體形的四氧化三鐵奈米微粒內，我們發現三價鐵離子佔有八面體位置的比率比一般四氧化三鐵塊材還來的高。然而，在削菱截角立方體形的四氧化三鐵奈米微粒內，其鐵離子在不同位置上的分佈情形就比較接近於四氧化三鐵塊材。此鐵離子分佈位置的不同可能是由於這兩種形狀的奈米微粒具有不同的比表面積和外露面所致，此結果也將有助於進一步研究四氧化三鐵的催化特性。最後，我們也發現鐵鉑-四氧化三鐵奈米微粒能顯著地增強MRI影像對比，並且效果優於目前市售之影像顯影劑，此顯著效果應歸因於鐵鉑核的高單位磁化量。另外具有自組裝排列的鐵鉑-四氧化三鐵奈米立方體有機會成為前瞻性多頻譜的影像增強劑。
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Yeh, Kuan-Wen, and 葉冠妏. "Formation of SiO2-Fe3O4 mesoporous nanoparticles for drug delivery." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/87568607195703350779.
Full textAbstract:
碩士<br>中原大學<br>奈米科技碩士學位學程<br>97<br>This study is divided into four parts. In the first part, the precursors FeCl3．6H2O and FeCl2．4H2O were dissolved in water and then alkali was added to synthesis magnetite nanoparticles by co-precipitation method and high rotation speed. The distribution of particle size, surface potential, morphology, lattice structure and magnetic properties of these particles were analyzed and compared with those of commercial magnetite. From the results, the particle size of magnetite, synthesized by using homogenizer, was about 10 nm. The magnetization is 90 emu/g, as high as the commercial one, from the SQUID analysis. We have successfully used homogenizer co-precipitation method to synthesis magnetite nanoparticlese without any surfacten. The distribution of particle size, surface potential, morphology and magnetization are all better then those of particles synthesized by hydrothermal method.
At the second part, we used Stöber process to synthesis the SiO2 nanoparticles and mesoporous SiO2 nanoparticles, and control the ratio of additives to make the SiO2 nanoparticles into mesopourous state to get high surface area and more ability to carry drugs. Results of TEM analysis indicated that SiO2 nanoparticles size was about 100-300 nm. On the other hand, adding Cationic surfactants--- Hexadecyltrimethylammonium(CTAB) could make SiO2 nanoparticles have mesoporous, which was approved by TEM analysis.
By combining the above two parts, we prepared the magnetic nanoparticle coated mesoporous SiO2 shell. We also used 200 nm PC membrane to synthesis SiO2 nanotubes. Same material but different state was used to increase surface area and ability of carrying drugs. Results of SEM analysis indicated that the nanottube length about 10μm and diameter is 200~300 nm.
Finally, we took all samples to test drug release ability. the swelling method was used to load the drug into nanoparticles and nanotubes. The Ultraviolet-Visible spectrometer was employed to analyzed drug releasing rate. The results of UV analysis indicated that nanoparticles with mesoporous surface carried more drug and had longer releasing time than nanoparticles without mesoporous surface. We concluded that the properties of two materials could be combined to develop a new therapy technology to reduce the side effect of drug loader and to increase the drug releasing efficiency from this study.
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曾維功. "Investigation on the Metabolism of Fe3O4 Nanoparticles in Rats." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/59483642418173426097.
Full textAbstract:
博士<br>國立臺灣師範大學<br>光電科技研究所<br>101<br>Magnetic nanoparticles (MNPs) of Fe3O4 have been widely applied in many medical fields, but few studies have clearly shown the outcome of particles following intravenous injection. We performed a magnetic examination using scanning SQUID biosusceptometry (SSB) and non-magnetic examinations for compressively studied the metabolism of intravenous MNPs. Based on the results of SSB analysis and those of established in vitro nonmagnetic bioassays, this study proposes a model of MNP metabolism consisting of an acute metabolic phase with an 8 h duration that is followed by a chronic metabolic phase that continues for 28 d following MNP injection. The major features included the delivery of the MNPs to the heart and other organs, the biodegradation of the MNPs in organs rich with macrophages, the excretion of iron metabolites in the urine, and the recovery of the iron load from the liver and the spleen. Increases in serum iron levels following MNPs injection were
accompanied by increases in the level of transferrin in the serum and the number of circulating red blood cells. These finding implied the iron form degradation of MNPs were reutilized for new hemoglobin and red blood cells synthesis.
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Chin, Chun Yi, and 金俊毅. "Synthesis and Application of Fe3O4 Nanoparticles with Different Morphologies." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/57032296289780602688.
Full textAbstract:
碩士<br>國立清華大學<br>化學工程學系<br>103<br>Abstract
In this research, we tried several different precipitation processes to synthesize Fe3O4 nanoparticles with different morphologies. We used only one precursor, i.e. FeSO4, which was oxidized to ferric sulfate by hydrogen peroxide. The two solutions were then mixed in appropriate ratio to obtain Fe3O4 using NaOH as the precipitant. TX-100 was used as a protective agent to keep the particles uniform. When both iron precursor solution and NaOH solution was pumped separately into TX-100 solution, spherical Fe3O4, uniform in size, was obtained. On the other hand, a two-step procedure, with the addition of molecules such as IPA, EG (ethylene glycol) or glycerol, we would get Fe3O4 particles in needle shape and also having complete (100%) conversion. The powders were then characterized by techniques such as XRD, SQUID, HRTEM, SEM, BET to obtain information on many characteristics of powders, such as size and uniformity, particle morphology, magnetic property, specific surface area, crystallinity, etc.. It is our hope to find correlation between these characteristics and processing conditions. These powders will be further processed as electrode materials and tested in a battery to find optimal performance.
For silver coated magnetic particles, we used AgNO3 and either IPA or EG as reducing agent and spherical Fe3O4 nanoparticles as core. The relative ratio between AgNO3 and Fe3O4 was varied with the objective to get uniform coating. The powders thus obtained was also subjected to several characterization techniques to get information on coating uniformity, crystalline nature, and magnetic property.
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Tsai, Tsu-Chi, and 蔡子祺. "Preparation and Characterization of Magnetic Fe3O4, Co, Ni Nanoparticles." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/98780772698755275356.
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碩士<br>南台科技大學<br>電子工程系<br>98<br>Magnetic nanoparticles have attracted an increasing interest in the fields of nanoscience and nanotechnology because of the unique and novel physiochemical properties that may find application in diverse areas, including biomedical imaging, drug delivery, sensing, memory devices, etc. To develop a cost-effective and facile method for the synthesis of magnetic nanoparticles, new synthetic methods have been flourishing for the control of their sizes, size uniformity, and shapes. Herein, we present a one-step synthesis to directly and quickly produce the nanoparticles coated with tetra ethylene glycol（TEG）, and study their structural and magnetic characteristics.
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Chia-HsienCho and 卓佳嫺. "Influence of Doping Superparamagnetic Fe3O4 Nanoparticles on Organic Solar Cells." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/54919724641578430303.
Full textAbstract:
碩士<br>國立成功大學<br>電機工程學系<br>102<br>The main purpose of our research focused on the effect of doping Fe3O4 magnetic nanoparticles (MNPs) into the assigned films of organic solar cells. Owing to the promising superparamagnetic characteristic and versatile applications in targeted therapy and MRI of Fe3O4 MNPs, we anticipate the photocurrent generated within the devices will induce electromagnetic interactions with dopants and raise the efficiency.
In our experiments, we successfully synthesized the hydrophilic Fe3O4 MNPs and hydrophobic OA-Fe3O4 MNPs by chemical co-precipitation method. The average diameter of both kinds of the as-synthesized particles is around 10 nm that possess superparamagnetism confirmed by SQUID VSM. The hydrophilic and hydrophobic particles were dissolved into PEDOT:PSS and P3HT:PCBM solutions with different weight percentages used as hole transport layer and active layer in bulk heterojunction (BHJ) structure, respectively.
The results exhibited PCE of devices which doped with 0.5wt% and 1wt% OA-Fe3O4 MNPs in P3HT:PCBM under conventional processing was raised by 〉20% and 〉40%, respectively. The doped active layers were further analyzed by FTIR, Cryo-TEM, AFM, UV-Vis, PL, and SAXS. From those measurements, we could figure out the chemical compositions of OA-Fe3O4 MNPs doped active layers were not changed with doping percentage but local surface morphology, particle dispersibility and microstructure were varied. Advanced light absorbability and suppressed PL intensity of 0.5wt% and 1wt% doped active layers were the main reasons why PCE was improved. The results of all the measurements were consistent with the devices performances.
In this research, we figured out the enhanced light absorbability was attributed to the improved P3HT crystallinity and crystallite domain size from SAXS measurements. The suppressed PL intensity was ascribed to the large-scale diffusion of PCBM into P3HT matrix to form aggregates. Furthermore, we offer an inferential model to interpret the relationship between the energy band and spintronics of the used organic semiconductor material. We infer that “The intersystem crossing (ISC) mechanism between singlet (1CT) and triplet (3CT) charge transfer state can be catalyzed by doping OA-Fe3O4 MNPs into P3HT:PCBM. The altered ratio of 3CT/1CT by ISC will affect the recombination process of electron hole pairs and will further suppress the loss of photocurrent.”
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Cheng, Fong-Yu, and 鄭豐裕. "The Preparation of Fe3O4 Nanoparticles and their Applications in Biomedicine." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/55536902545845859091.
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博士<br>國立成功大學<br>化學系碩博士班<br>94<br>By modifying synthesized method to prepare water-soluble and biocompatible Fe3O4 nanoparticles which no polymer coated is a new technology. The as-synthesized Fe3O4 nanoparticles not only have above properties but also provide functional groups to achieve derivation. This method simplified some condictions of reaction, and it reduced some problems in synthesized methods which developed before. The Fe3O4 nanoparticles can apply to different fields by modifying the surface of them. According to diverse surface modifications of the Fe3O4 nanoparticles, their suited applications such as biomedicine, analysis, and separation are different. The Fe3O4 nanoparticles also have no limits required by biomedicine and provide many new ideas for developments and reasearchs. They can combine with most biomolecules to become a new-type nanomaterial, developing more powerful technologies.
There are three types of Fe3O4 nanoparticles prepared in this article. First, ammonium-type Fe3O4 nanoparticles can control the behaviors of DNA absorption and desorption by adjusting pH values. This reversible process can set up a simple model that applies to drug delicery systems. Second, carboxyl acid-type Fe3O4 nanoparticles could successfully separate genomic DNA in a complex condition of human whole blood. This separation technology of magnetic nanoparticles affords a rapid, easy, and efficient method in detecting diseases. The final type is amino-type Fe3O4 nanoparticles. They can achieve many applications, enzyme immobilization, mass-spectrum analysis, DNA probe, polymerase chain reaction (PCR), protein separation and contrast agent, combined with other molecules. Amino-type Fe3O4 nanoparticles is more important type than two types because of its wide variations in modifying functional groups on the surface of nanoparticles. With different functional groups, they can be applied to specifiec fields which needed.
In this article, arrording to different chatacterastics of functional groups, the three different types of Fe3O4 nanoparticles could be applied in various fields. Their detail or special properties could be understanded with experimental results and a serious of tests. With the advantages of combining chemical molecules and biomolecules, the applications of Fe3O4 nanoparticles extend and develop more powerful and new uses in biomedicine field, including separation, diagnosis, detection and image. The as-synthesized Fe3O4 nanoparticles in this modified method really show its advantages, new technologies, stability, and variable applications in many fields.
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Lin, Yen-hung, and 林彥宏. "Preparation and magnetic properties of Fe3O4-SiO2 core-shell nanoparticles." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/47198140031908400219.
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碩士<br>東海大學<br>物理學系<br>92<br>The inhomogeneous atomic bonding was generated innano-transition zone between core and shell structure. Thus, several researchers have focused on special electro-magnetic properties, optical characteristics and catalytic properties of core-shell structure particles.
We have prepared the Fe3O4-SiO2 Core-shell nanoparticles by using Stober process. In this research, TEM and EDX will be used to study the samples, we find that amorphous SiO2 shell has coated with Fe3O4 nanoparticles. When the time of preparing is 24 hours, we can get the maximum thickness.
Besides, in this study, we also study the structure and magnetic properties of the different thicknesses of SiO2 shell.
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Jia-yu, Liou, and 劉佳瑜. "Studies of Magnetic Chitosan/Fe3O4 Micro/Nanoparticles for Nattokinase Delivery." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/30331379843713576317.
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碩士<br>大葉大學<br>生物產業科技學系<br>98<br>In this study, chitosan/iron (II, III) oxide/ nattokinase micro/nano particles were produced by low-temperature spray-drying. The magnetic micro/nano particles were further study the transportation behavior between cells using an in vitro model of human oral squamous cell carcinoma (KOSC-3). In order to prepare micro/nano particles, three suspensions of 0.5、1、1.5％ (w/v) chitosan with iron oxide were first mixed with nattokinase and then spray-dried in a low temperature condition. The samples were analyzed by field emission scanning electron microscopy (FESEM). It was found that the size of all the particles were in the range of 767 nm to 2.1 μm. The cytotoxicity of micro/nano particles was determined by MTT assay. No observable toxicity was noted on KOSC-3 cells by incubation with chitosan/iron (II, III) oxide/ nattokinase micro/nano particles. In vitro studies performed on KOSC-3 cell showed a pronounced opening of the cell junctions obtained by transepithilial electrical resistance (TEER) assay. In the meantime, the medium in the outside of insert was taken and a QuantiProTM BCA assay kit was used to investigate the release and transportation of nattokinase. The results indicated that the samples from multi-stage electromagnet collector had significantly improved transportation properties by the attraction of a magnet. However, the largest and smallest particles behave differently and that is worthy of further study.
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Liu, Cheng-Hao, and 劉成浩. "Fe3O4 Nanoparticles for Fluorescence Sensing of Specific Substrate and Catecholamines." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/26357434797132981543.
Full textAbstract:
碩士<br>國立中山大學<br>化學系研究所<br>99<br>The first study reports the development of a reusable, single-step system for the detection of specific substrates using oxidase-functionalized Fe3O4 nanoparticles (NPs) as a bienzyme system and using amplex ultrared (AU) as a fluorogenic substrate. In the presence of H2O2, the reaction pH between Fe3O4 NPs and AU was similar to the reaction of oxidase and the substrate. The catalytic activity of Fe3O4 NPs with AU was nearly unchanged following modification with poly(diallyldimethylammonium chloride) (PDDA). Based on these features, we prepared a composite of PDDA-modified Fe3O4 NPs and oxidase for the quantification of specific substrates through the H2O2-mediated oxidation of AU. By monitoring fluorescence intensity at 587 nm of oxidized AU, the minimum detectable concentrations of glucose, galactose, and choline were found to be 3, 2, and 20 μM using glucose oxidase-Fe3O4, galactose oxidase-Fe3O4, and choline oxidase-Fe3O4 composites, respectively. The identification of glucose in blood was selected as the model to validate the applicability of this proposed method.
The second study follows the first one. Using the catalytic activity of Fe3O4 NPs with AU to detect four kinds of neurotransmitter, such as dopamine, L-DOPA, adrenaline (epinephrine) and noradrenaline (norepinephrine). Because of there is specific interaction between Fe3O4 NPs and catecholamines (CAs), the Fe3O4 NPs will form CAs-Fe3O4 NPs composites in presence of CAs. The CAs on the Fe3O4 NPs surface must shelter the reaction between AU and H2O2, cause the fluorescence to be turned-off. The CAs just like a inhibitor, to inhibit the catalytic activity of Fe3O4 NPs. Therefore, we could use this inhibited system to detect the CAs compound concentration in the real sample.