Abstract
In this work, we investigated the local colloidal structure of ferrofluid, in the presence of the external magnetic field. The nanoparticles studied here are of the core-shell type, with the core formed by manganese ferrite and maghemite shell, and were synthesized by the coprecipitation method in alkaline medium. Measures of Small Angle X-ray Scattering (SAXS) performed in the Brazilian Synchrotron Light Laboratory (LNLS) were used for the study of the local colloidal structure of ferrofluid, so it was possible to study two levels of structure, cluster and isolated particles, in the regimes with and without applied magnetic field. In the methodology used here there is a combination of the information obtained in the system with and without magnetic field application. In this way, it is possible to undertake a better investigation of the colloidal dispersion. The theoretical formalism used: (i) the unification equation proposed by Beaucage G.; (ii) the analysis of the radial distribution function p ( r ) and (iii) theoretical calculation of the radius of gyration as a function of the moment of inertia of the spherical of n-nanoparticles.
Highlights
Ferrofluids are a colloidal suspension of dispersions of magnetic nanostructures in a specific carrier liquid [1,2,3]
An excess of positive charges occurs due to the oxidation of Mn+2 to Mn+3 in the synthesis process, in order to balance exactly the extra positive charge that appears in the formula is inserted a δ parameter of 0.48 to adjust the electronegativity
The Rietveld refinements of X-ray Powder Diffraction (XPD) and Neutron Powder Diffraction (NPD) by Martins and the Pair Distribution Function (PDF) made by Moreira, both performed for non-stoichiometric ferrites, 126 more Mn+3 than other valence states Mn+2 and Mn+4, resulting in an average oxidation of +3
Summary
Ferrofluids are a colloidal suspension of dispersions of magnetic nanostructures in a specific carrier liquid [1,2,3]. We can emphasize the study of the local colloidal structure with the objective of improving in the applications in the field of medicine, with specific use in hyperthermia in the treatment of cancer In this context, we would like to highlight some works, pertinent to the influence of the colloidal organization of ferrofluids on the effect of hyperthermia: Myrovali et al (2016) [11] has verified the role of chain formation to further optimize the heating efficiency in the hyperthermia of Fe3O4 magnetic particles when magnetically aligned; Abenojar et al (2016) [12] effect of nanochain and nanocluster formation on magnetic hyperthermia properties; Serantes et al (2014) [13] observed that a system with chain-like arrangement biomimicking magnetotactic bacteria has the superior heating performance, increasing more than 5 times in comparison with the randomly distributed system when aligned with the magnetic field; Martinez-Boubeta et al (2013) [14] heat generation of iron-oxide nanoparticles for magnetic hyperthermia; Mehdaoui et al (2013) [15] increase of magnetic hyperthermia efficiency due to dipolar interactions in magnetic nanoparticles; and Bañobre-López et al (2013) [16] use of magnetic nanoparticles-basead hyperthermia in cancer therapy
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