Banca de DEFESA: ELOISE CRISTINA DE SOUZA RODRIGUES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ELOISE CRISTINA DE SOUZA RODRIGUES
DATA : 03/02/2017
HORA: 14:30
LOCAL: Auditório do DFTE
TÍTULO:

Synthesis and characterization of α-Fe and magnetite nanocomposite for biomedicalk applications

PALAVRAS-CHAVES:

Synthesis and characterization of α-Fe and magnetite nanocomposite for biomedicalk applications

PÁGINAS: 130
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
SUBÁREA: Física da Matéria Condensada
RESUMO:

Iron Oxide nanoparticles have been used em 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 ball 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 α-Fe, the second group is composed of magnetite, wüstite and α-Fe nanoparticles. 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 Mössbauer spectroscopy. The magnetic properties were studied through AC susceptibility and DC magnetization as a function of temperature and field.  From the Mössbauer studies we noticed a significant fraction of Fe2,5+ located in octahedral sites of iron oxide, this result indicates that the samples  has a an stoichiometry similar to pure magnetite. The magnetic measurements showed the Verwey transition at about 120 K. From the TEM images we verified that the wüstite phase is formed on the surface of magnetite nanoparticles. Therefore, we showed that the wüstite phase and oleic acid surfactant prevent the magnetite nanoparticles from further oxidation. The shift of hystereis loops observed in the field-cooled samples was ascribed to exchange interaction between the wüstite and magnetite phases. The AC susceptibility 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 11º C and 53º C for samples functionalized and bare, respectively. The combination of magnetic properties, the ability to release heat in presence of an AC field, and the stability of particles in aqueous suspension suggest that these samples are good candidates for magnetic hyperthermia.

MEMBROS DA BANCA:
Interno - 350830 - JOSE HUMBERTO DE ARAUJO
Externo à Instituição - JOÃO MARIA SOARES - UERN
Presidente - 1674707 - MARCO ANTONIO MORALES TORRES
Externo à Instituição - NELSON ORLANDO MORENO SALAZAR - UFS
Interno - 1675199 - SUZANA NOBREGA DE MEDEIROS