Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-06-06T20:22:53Z No. of bitstreams: 1 NagilsonMendesDeSousa_DISSERT.pdf: 26377714 bytes, checksum: 39811438b6914861990ecb38bbfc438f (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-08T19:15:26Z (GMT) No. of bitstreams: 1 NagilsonMendesDeSousa_DISSERT.pdf: 26377714 bytes, checksum: 39811438b6914861990ecb38bbfc438f (MD5) / Made available in DSpace on 2016-06-08T19:15:26Z (GMT). No. of bitstreams: 1 NagilsonMendesDeSousa_DISSERT.pdf: 26377714 bytes, checksum: 39811438b6914861990ecb38bbfc438f (MD5) Previous issue date: 2015-09-14 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Nanopart?culas (Nps) s?o importantes no estudo de novos fen?menos na f?sica e no desenvolvimento de novas aplica??es tecnol?gicas. Nanopart?culas magn?ticas met?licas tais como N?quel e Cobalto surgem como objetos promissores devido as suas aplicabilidades em v?rias ?reas da ci?ncia e tecnologia. No presente trabalho apresentamos um estudo sobre o m?todo de s?ntese, caracteriza??o estrutural e magn?tica em nanopart?culas de Ni e Co. As amostras foram preparadas pelo m?todo sol-gel modi cado e formadas nos poros do pol?mero quitosana, a redu??o ocorreu em aus?ncia de uxo de Hidrog?nio. A fase cristalina do Ni e Co ? c?bica de face centrada e seus di?- metros variaram de 59-77nm e 19-50nm, respectivamente. As superf?cies das nanopart?culas foram naturalmente passivadas com seus mon?xidos apresentando estabilidade qu?mica por longos intervalos de tempo. A estrutura formada ? do tipo n?cleo/casca, o que favoreceu as intera??es de exchange bias entre o n?cleo ferromagn?tico (FM) e a casca antiferromagn?tica (AFM). As condi??es de s?ntese foram otimizadas para obter principalmente a fase FM. Ambas NPs foram submetidas ? a??o de um campo magn?tico AC e houve aquecimento r?pido at? atingir temperatura de aproximadamente 140?C em intervalos de tempo de at? 5 min. As amostras dispersadas em ?gua, atingiram temperaturas de 40- 59?C de aquecimento em at? 10 minutos, mostrando potencial para aplica??es em hipertermia magn?tica. / Nanoparticles are importante for the study of new phenomena and for the development of new applications. Metallic magnetic nanoparticles like Cobalt and Nickel are important for their applications in nanoscience and nanotechnology. In this work, we report on the synthesis and characterization of Ni and Co nanoparticles. The nanoparticles were prepared by the modi- ed sol-gel method and were formed in the pore-network of the biopolymer quitosan. The reduction occurred in absence of H2 ux. The metallic particles and their monoxides have a face-centered- cubic structure. The metallic particles sizes ranged from 59 to 77 nm and from 19 to 50 nm for Ni and Co, respectively. Their monoxides chemically passivated the metallic cores, and after several weeks we have not observed further increase in oxidation. The synthesis method was tuned to obtain mainly the ferromagnetic phase. The system behaves like a core/shell structure with a ferromagnetic core and an antiferromagnetic shell. Exchange bias e ect was observed at temperatures below the N?el temperature. Both systems were submitted to an alternated magnetic eld and the heat released by the particles increased the temperature to 140?C in an interval of 5 min. Similar studies in samples dispersed in water increased the temperatures to 40-59?C, these results suggest that these materials are candidates for magnetic hyperthermia.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-06-13T19:40:46Z No. of bitstreams: 1 EloiseCristinaDeSouzaRodrigues_TESE.pdf: 3994565 bytes, checksum: b9c31f2d2181715131a7f58b458b5b2a (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-06-16T20:54:23Z (GMT) No. of bitstreams: 1 EloiseCristinaDeSouzaRodrigues_TESE.pdf: 3994565 bytes, checksum: b9c31f2d2181715131a7f58b458b5b2a (MD5) / Made available in DSpace on 2017-06-16T20:54:23Z (GMT). No. of bitstreams: 1 EloiseCristinaDeSouzaRodrigues_TESE.pdf: 3994565 bytes, checksum: b9c31f2d2181715131a7f58b458b5b2a (MD5) Previous issue date: 2017-02-03 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Nanopart?culas de ?xido de Fe t?m sido muito usadas em aplica??es biom?dicas devido a sua biocompatibilidade e biodegradabilidade. Dentre dessas aplica??es destacamos a hipertermia magn?tica para o tratamento de diversos tipos de c?nceres. Neste trabalho usamos a moagem de alta energia para a produ??o de nanopart?culas de magnetita com tamanho inferior a 70 nm. Preparamos dois grupos de amostras, o primeiro grupo apresentou as fases de magnetita e ?-Fe, composto pelas amostras S1 e S3, o segundo grupo apresentou as fases de magnetita, ?-Fe e w?stita, amostras S2 e S4. Para melhorar a dispers?o dos materiais em meio aquoso, revestimos as nanopart?culas com o surfactante ?cido oleico e o pol?mero Pluronic-F127. As propriedades estruturais e qu?micas das amostras foram analisadas atrav?s da difra??o de raios X, microscopia eletr?nica de transmiss?o e espectroscopia M?ssbauer. As propriedades magn?ticas foram estudadas atrav?s de medidas de susceptibilidade AC e de medidas de magnetiza??o em fun??o do campo e da temperatura. Das medidas M?ssbauer, para a amostra S4, observamos uma raz?o entre as ?reas dos espectros referentes aos s?tios octaedrais e tetraedrais compat?veis com a magnetita estequiom?trica. As medidas magn?ticas mostraram a transi??o de Verwey da magnetita em 120 K para os dois grupos de amostras. Atrav?s das imagens de microscopia eletr?nica, de S4, verificamos que a w?stita encontra-se depositada sobre as nanopart?culas de magnetita. O nosso estudo mostra que a presen?a da w?stita e a funcionaliza??o com ?cido oleico evitaram a oxida??o do Fe2+ presente na magnetita. O deslocamento das curvas de histerese, nas medidas feitas com a amostra resfriada em presen?a de campo magn?tico, ? atribu?do ? intera??o de troca que ocorre na interface entre a w?stita e a magnetita. As medidas de susceptibilidade AC mostraram picos caracter?sticos de paredes de dom?nio, para a amostra com duas fases, indicando que uma parcela das part?culas ? multidom?nio. Quando as nanopart?culas funcionalizadas e n?o funcionalizadas foram submetidas a um campo magn?tico alternado apresentaram uma varia??o de temperatura e 11? C e 53? C, para S3P e S1, respectivamente, e para S4 a varia??o de temperatura foi de 14? C. Os resultados indicam que as amostras t?m potencial para uso em hipertermia magn?tica. / Oxide nanoparticles have been used in several biomedical applications due to their biocompatibility and biodegradability. Among these applications, magnetic hyperthermia of tumors has been proposed as an alternative treatment of several neoplastic diseases. In this work, we have used high energy milling to produce iron oxide nanoparticles with sizes smaller than 70 nm. We have prepared two groups of samples, the first group is composed of magnetite and ?-Fe, samples S1 and S3, the second group is composed of magnetite, w?stite and ?-Fe nanoparticles, samples S2 and S4. To improve the sample?s dispersibility in aqueous medium, the samples were functionalized with oleic acid and Pluronic-F127 three-block copolymer. The structural and chemical properties of samples were studied through x-ray diffraction, transmission electron microscopy (TEM) and M?ssbauer spectroscopy. The magnetic properties were studied through AC susceptibility and DC magnetization as a function of temperature and field. From the M?ssbauer studies, for the sample S4, we observed a ratio between the areas of the spectra for the octahedral and tetrahedral compatible with stoichiometry magnetite. The magnetic measurements showed the Verwey transition at about 120 K, for the two groups of samples. From the TEM images, S4, we verified that the w?stite phase is formed on the magnetite nanoparticles. Therefore, we showed that the w?stite phase and oleic acid surfactant prevent the magnetite nanoparticles from further oxidation. The shift of hystereis loops observed in the field cooled samples is ascribed to exchange interaction between the w?stite and magnetite phases. The AC susceptibility, from S4, showed characteristic peaks of magnetite wall domains, this result indicated that a fraction of particles are multidomain. The samples were submitted to an AC magnetic field and we observed an increase in temperature of e 11? C and 53? C for samples functionalized and bare, for S1 and S4 respectively, for sample S4, the increase in temperature, was of 14? C. The combination of magnetic properties, the ability to release heat in presence of an AC, and the stability of particles in aqueous suspension suggest that these samples are good candidates for magnetic hyperthermia.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-11-18T12:11:41Z No. of bitstreams: 1 WellingtonCantanhedeDosSantos_DISSERT.pdf: 28481348 bytes, checksum: 2d5163f73607a4e015bf9536232e933b (MD5) / Approved for entry into archive by Elisangela Moura (lilaalves@gmail.com) on 2015-11-18T15:01:11Z (GMT) No. of bitstreams: 1 WellingtonCantanhedeDosSantos_DISSERT.pdf: 28481348 bytes, checksum: 2d5163f73607a4e015bf9536232e933b (MD5) / Made available in DSpace on 2015-11-18T15:01:11Z (GMT). No. of bitstreams: 1 WellingtonCantanhedeDosSantos_DISSERT.pdf: 28481348 bytes, checksum: 2d5163f73607a4e015bf9536232e933b (MD5) Previous issue date: 2014-03-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / No presente trabalho foram sintetizados comp?sitos, a partir da moagem de altaenergia dos precursores hidroxiapatita - HAp (Ca10(PO4)6(OH)2) e ferro met?lico (?-Fe),com o intuito de serem utilizados em hipertermia magn?tica no tratamento do c?ncer. Osprodutos da moagem foram caracterizados por difratometria de raios X (DRX),microscopia eletr?nica de varredura (MEV), espectroscopia de energia dispersiva (EDS),medidas de magnetiza??o em fun??o do campo aplicado e medidas de temperatura emfun??o do campo alternado. Os DRX das amostras batidas de HAp/Fe revelaram somente apresen?a dos precursores. O MEV mostrou aglomerados com formatos irregulares. Ascurvas de magnetiza??o obtidas apresentam casos t?picos de comportamentoferromagn?tico fraco. Para as amostras batidas e submetidas a tratamento t?rmico asseguintes fases foram identificadas: HAp (Ca10(PO4)6(OH)2) , hematita (Fe2O3) e ferrofosfato tric?lcio, FeTCP, Ca19Fe2 (PO4)14. Analisando os resultados de M x H, verificou-seuma redu??o na magnetiza??o de satura??o, tendo em vista que o Fe foi incorporado ?HAp. As curvas de histerese, obtidas a 300 K, s?o caracter?sticas de amostras que possuemmais de uma fase. Em 77 K, o comportamento da curva de histerese ? influenciado pelapresen?a da hematita que ? antiferromagn?tica. J? em T = 4,2K, ? observado umcomportamento ferromagn?tico fraco. Al?m disso, verifica-se o efeito de ?exchange bias?.Os resultados obtidos das medidas de temperatura em fun??o do campo alternado s?opromissores para aplica??es em hipertermia magn?tica e outras aplica??es biom?dicas. / In this work, composites were prepared using high energy mechanical milling from the precursors hydroxyapatite - HAp (Ca10(PO4)6(OH)2) and metallic iron ( -Fe ). The main goal here is to study composites in order to employ them in magnetic hyperthermia for cancer therapy. The produced samples were characterized by X-ray di raction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), magnetization curves as a function of applied eld (MxH), and nally measurements of magnetic hyperthermia. The XRD patterns of the milled samples HAp/Fe revealed only the presence of precursor materials. The SEM showed clusters with irregular shapes. The magnetization curves indicated typical cases of weak ferromagnetic behavior. For samples submitted to grinding and annealing, the identi ed phases were: HAp (Ca10(PO4)6(OH)2), hematite (Fe2O3) and Calcium Iron Phosphate (Ca9Fe(PO4)7). Analyzing the results of MxH, there was a reduction of the saturation magnetization, given that the Fe was incorporated into HAp. Hysteresis curves obtained at 300 K are characteristics of samples possessing over a phase. At 77 K, the behavior of the hysteresis curve is in uenced by the presence of hematite, which is antiferromagnetic. Already at T = 4.2 K, it is observed a weak ferromagnetic behavior. Furthermore, there is the e ect of exchange bias. Regarding the magnetic hyperthermia, the results of temperature measurements as a function of the alternating eld are promising for applications in magnetic hyperthermia and other biomedical applications.