ZnxFe3-xO4 nanoparticles: effects of morphology, magnetism and composition on the Magnetic Fluid Hyperthermia response

ADRIELE APARECIDA DE ALMEIDA; ENIO LIMA JR; ELIN WINKLER; MARCELO VASQUEZ MANSILLA; HORACIO E. TROIANI; EMILIO DE BIASI; ROBERTO D. ZYSLER; LUIS RODRIGUEZ; DANIEL FREGENEL; GERARDO F GOYA; TEOBALDO TORRES

Bariloche

Simposio; XXII Latin American Symposium on Solid State Physics; 2018

Magnetic fluid hyperthermia (MFH) consists in the heating of a target tissue by the magnetic losses of a ferro- or ferrimagnetic materials (MNPs) using ac magnetic fields in the radiofrequency range. Ferrite nanoparticles are interesting systems for MFH with a large number of potential applications in this field. The key parameter in MFH is the specific power absorption (SPA) of the nanoparticles, and is determined by the magnetic, morphological and rheological properties of the solvent/MNPs. In this work, we present a study of the morphological and magnetic properties of ZnXFe3-XO4 nanoparticles in order to understand their MFH response. By controlling the size and the composition of our samples we tuned the effective magnetic anisotropy and the saturation magnetization, which allowed us to optimize the SPA of our material in MFH experiments. MNPs of different sizes between 8-30nm were synthesized by high temperature thermal decomposition of organometallic precursors. The sample morphology was determined by TEM, the composition was analyzed by PIXE, and the magnetic properties were determined by magnetization measurements and ferromagnetic resonance experiments. The magnetic hyperthermia experiments were performed as a function of both frequency (228 kHz £ f £ 817 kHz) and amplitude (0 £ H_0 £ 24 kA/m) in different rheological conditions (i.e., different viscosities). The resulting SPA values were analyzed in terms of the different mechanisms that determine the magnetic losses. These mechanisms are related to the relaxation of the magnetic moment and phase shift with the applied field. With a simple model, we were able to simulate the dependence of the SPA with the frequency for the complete series of samples. We also present measurements of the catalytic peroxidase-like activity to produce free radicals of the nanoparticles under emulated physiological conditions, which is critical for potential clinical uses of these systems.