Detalhes bibliográficos
| Ano de defesa: |
2016 |
| Autor(a) principal: |
Silva, Anderson Costa da
 |
| Orientador(a): |
Bakuzis, Andris Fisgueiroa
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| Banca de defesa: |
Bakuzis, Andris Figueiroa,
Miotto, Ronei,
Silva, Sebastião William da,
Bufaiçal, Leandro Felix,
Pelegrini, Fernando |
| Tipo de documento: |
Tese
|
| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Federal de Goiás
|
| Programa de Pós-Graduação: |
Programa de Pós-graduação em Fisica (IF)
|
| Departamento: |
Instituto de Física - IF (RG)
|
| País: |
Brasil
|
| Palavras-chave em Português: |
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| Palavras-chave em Inglês: |
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| Área do conhecimento CNPq: |
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| Link de acesso: |
http://repositorio.bc.ufg.br/tede/handle/tede/6373
|
Resumo: |
In this work we investigated the magnetothermal efficacy of two nanocarriers, magnetic fluids (MF) and magnetoliposomes (ML), with potential for oncology therapy. Ferrofluids based on manganese ferrite nanoparticles, surface coated with citric acid, were synthesized. Magnetoliposomes, vesicles containing magnetic nanoparticles inside, were prepared by the extrusion method. X-ray diffraction corfimed the spinel structure, while transmission electron microscopy revealed spherical nanoparticles with a lognormal size distribution and mean diameter of (11,1 ± 3,5) nm. Magnetization curves, at quasi-static conditions revealed particles at the superparamagnetic regime. A reduction in the saturation magnetization in comparison with bulk samples were explained by a nonmagnetic shell with thickness of 1.1 nm. The concentration and particle size distribution of the liposomes (mean diameter of 180 nm) were obtained from the nanoparticle tracking analysis (NTA). The combination of magnetometry and NTA data revealed an encapsulation particle volume fraction in the range of 0.26 to 0.83% for the samples. Magnetic birefringence data showed a higher fraction of aggregates in ML in comparison to MF. Magnetic hyperthermia experiments were perfomed at distinct frequencies (111 -632 kHz) and field amplitudes (up to 250 Oe) for distinct ML and MF samples. In general, we found a reduction of magnetothermal efficacy for magnetoliposomes when compared to MF. although the effect is less evident at lower frequencies (<170 kHz). The explanation was obtained through a new theoretical model that, not only takes into account the effect of dipolar interaction in the magnetic anisotropy, but also the reduction of susceptibility due to blocked nanoparticles. This contribution was shown to be strongly dependent upon field frequency, amplitude and aggregates in the suspension. |
