Avaliação dos efeitos das hipertermias magnética e fototérmica na síntese de heteroestruturas à base de nanopartículas de MnFe2O4 e Au
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2015-12-14
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Universidade Federal de Goiás
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The purpose of this project is to synthesize and characterize heterostructures composed by manganese
ferrite nanoparticles (MnFe2O4 NPs) and gold nanoparticles (Au NPs) able to: 1) respond to external
alternating magnetic fields, what would enable their use in cancer diagnostic as contrast agentes for
magnetic resonance imaging, as well as in cancer treatment via magnetic hyperthermia; 2) respond to
eletromagnetic radiation, what would enable their use in cancer diagnostic as contrast agents for X-ray
computed tomography (CT), as well as in cancer treatment via photothermal hyperthermia. We evaluate
four MnFe2O4-Au heterostructures synthesis protocols. On Protocol 1, we use part of the energy of a laser
beam (808 nm, 800 mW) to promote the nucleation of Au NPs at the surface of previously synthesized
MnFe2O4 NPs covered by DMSA (dimercaptosuccinic acid). On Protocol 2, we use part of the energy of an
alternating magnetic field (333,8 kHz, 17 mT) to promote this nucleation. We also perform an analysis of
the influence of MnFe2O4 NPs covering layer, by comparing the ionic surfactants DMSA and sodium
citrate. On Protocols 3 and 4, both the magnetic cores (MnFe2O4 NPs) and the metalic cores (Au NPs) are
previously synthesized. Therefore, three Au NPs synthesis methods are evaluated. On Protocol 3, we
promote the coupling between Au NPs and MnFe2O4-DMSA NPs using part of the energy from the same
laser beam used on Protocol 1. On Protocol 4, we promote the coupling between cysteine-covered Au NPs
and lysine-covered MnFe2O4 NPs via peptidic reaction between these two aminoacids. Finally, we conduct
a comparative analysis between magnetic and photothermal hyperthermia, proposing a method for the
determination of the optical SLP (Specific Loss Power). Moreover, we submit some of our samples to CT
imaging. Protocol 1 is the best one in terms of covering the magnetic core by Au NPs. Protocol 2 allows the
nucleation of Au NPs with diameters greater than the ones obtained via Protocol 1. Protocols 3 and 4 offer
nanostructures with better potential with respect to their use as contrast agents in CT. However, the final
yield of all four protocols is very low. Comparing magnetic and photothermal hyperthermia, we verify that
the optical SLP is two to three orders of magnitude greater than the magnetic SLP under the assessed
conditions, what suggests that protocols using laser beams have more energy available for the
nucleation/coupling of Au NPs at the surface of MnFe2O4 NPs than those using alternating magnetic fields
or simple heating on hot plate.
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SOUSA JÚNIOR, A. A. Avaliação dos efeitos das hipertermias magnética e fototérmica na síntese de heteroestruturas à base de nanopartículas de MnFe2O4 e Au. 2015. 161 f. Dissertação (Mestrado em Fisica) - Universidade Federal de Goiás, Goiânia, 2015.