Desenvolvimento de nanopartículas de magnetita para aplicações biológicas : propriedades estruturais, microestruturais e magnéticas

• Autor(a) principal: Bini, Raquel Dosciatti
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/2660
• topic: Nanoparticulas magnéticas; Superparamagnetismo; Magnetita; Biomedicina; Brasil.; Magnetic nanoparticles; Superparamagnetism; Magnetite; Biomedicine; Brazil.; Ciências Exatas e da Terra; Física

The search for new technologies has stimulated the development of new materials whose properties can be adjusted for specific purposes. The magnetic nanoparticles of iron oxides which exhibit superparamagnetic behavior, have enormous potential for technological and biomedical applications. In this study, magnetite nanoparticles (Fe3O4) were synthesized by two different chemical routes, polymer PVA assisted synthesis and copreciptation in the presence or absence of oleic acid as a surface protector. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The XRD patterns showed characteristic peaks of magnetite phase related to the crystallographic planes (111), (220), (311), (400), (422), (511) and (440). The FTIR spectra indicated the absence of vibration bands at 975, 1030, 1080 and 2940 to 2870 cm-1 that characterizes PVA molecule, as well as the samples through coprecipitation, the presence of oleic acid was confirmed by bands 2923, 2852, 1685 and 1519 cm-1. The magnetization measurements showed superparamagnetic behavior for magnetite nanoparticles samples synthesized by the two different methods. The measured values for saturation magnetization were 21.4 and 55.3 emu/g for samples prepared using the polymer PVA assisted synthesis and coprecipitation, respectively. This fact shows a dependence of the magnetic properties of magnetite nanoparticles with the chosen methods of synthesis. The electron microscopic images also show that oleic acid promoted the stability of the nanoparticles when suspended in hexane with a significant reduction of the agglomerated and better distribution of the particles.