Made available in DSpace on 2015-04-14T13:59:06Z (GMT). No. of bitstreams: 1
457483.pdf: 5023547 bytes, checksum: e9f63d304ec1410bd1e9d8f328ceaa18 (MD5)
Previous issue date: 2014-02-28 / In this work we investigated the synthesis, characterization and contrast properties of core-shell nanoparticles of iron oxide coated with dextran and functionalized with amine groups. Fluorophores groups were incorporated on the nanoparticles surface, allowing their use as contrast agents for magnetic resonance imaging and optical microscopy. The nanoparticles synthesis was performed by the coprecipitation method of iron salts in basic medium, along with the polymer coating. The synthesis parameters were modified to investigate their influence on the size distribution of nanoparticles. Transmission electron microscopy observations and dynamic light scattering showed a magnetic iron oxide core with an average diameter around 10-15 nm and the total average hydrodynamic diameters between 16-50 nm, depending on the synthesis conditions. The FTIR spectra showed characteristics absorption bands pure dextran in the synthesized core-shell nanoparticles. The zeta potential analysis showed positive values close to zero and stability at neutral pH. The magnetization curves of the nanoparticles revealed superparamagnetic behavior, with the characteristic absence of hysteresis and no magnetization at zero field. The UV-vis and flow cytometry analysis revealed the presence of fluorescent groups in the nanoparticles and the feasibility of their use in optical imaging. Studies of relaxation times of the nuclear magnetization have shown the decrease of the magnetic resonance signal with increasing nanoparticles concentration, reducing the relaxation times T1 and T2 in the nanoparticle aqueous solutions. The relaxivities ratios (r2/r1) ranged between 5.06 and 51.0 and were within the value of iron oxide contrast agents commercially available. / Neste trabalho, pesquisou-se a s?ntese, a caracteriza??o e as propriedades de contraste por imagem de nanopart?culas core-shell de ?xido de ferro, revestidas com dextran e funcionalizadas com grupos amina. Grupos fluor?foros foram incorporados na superf?cie das nanopart?culas, possibilitando seu uso como agente de contraste para imageamento por resson?ncia magn?tica e por microscopia ?ptica. As s?nteses das nanopart?culas foram realizadas pelo m?todo de coprecipita??o de sais de ferro, com o pol?mero de revestimento. Par?metros da s?ntese foram modificados para averiguar sua influ?ncia na distribui??o de tamanho das nanopart?culas. Os resultados da morfologia e da distribui??o de tamanhos por TEM e DLS mostraram um n?cleo com di?metros m?dios entre 10-15 nm e di?metros hidrodin?micos m?dios entre 16-50 nm, dependendo do procedimento de s?ntese. Os espectros de FTIR apresentaram bandas de absor??o caracter?sticas das liga??es presentes no dextran puro e nas nanopart?culas sintetizadas. A an?lise do potencial zeta revelou valores positivos pr?ximos de zero e estabilidade em pH neutro As medidas de magnetiza??o revelaram comportamento superparamagn?tico pela aus?ncia de histerese na curva de magnetiza??o. As an?lises por UV-vis e por citometria de fluxo revelaram a presen?a dos grupos fluorescentes nas nanopart?culas e a viabilidade de seu uso em imagens ?pticas. Os estudos nos tempos de relaxa??o magn?tica nuclear mostraram efeitos de contraste, perturbando a intensidade de sinal com o aumento da concentra??o, diminuindo os tempos de relaxa??o T1 e T2 das solu??es aquosas de nanopart?culas. A rela??o entre as relaxividades (r2/r1) foi entre 5.06 e 51.0, dentro dos valores dos agentes de contrastes de ?xido de ferro comercialmente dispon?veis.
| Identifer | oai:union.ndltd.org:IBICT/oai:tede2.pucrs.br:tede/3253 |
| Date | 28 February 2014 |
| Creators | Oliveira, Elisa Magno Nunes de |
| Contributors | Papal?o, Ricardo Meurer |
| Publisher | Pontif?cia Universidade Cat?lica do Rio Grande do Sul, Programa de P?s-Gradua??o em Engenharia e Tecnologia de Materiais, PUCRS, BR, Faculdade de Engenharia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da PUC_RS, instname:Pontifícia Universidade Católica do Rio Grande do Sul, instacron:PUC_RS |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | -7432719344215120122, 500, 600, -655770572761439785 |
Page generated in 0.0027 seconds