Znx Fe3-x O4 nanoparticles: effects of morphology, magnetism and composition on the Magnetic Fluid Hyperthermia response

ADRIELE ALMEIDA; ENIO LIMA JR.; ELIN WINKLER; MARCELO VÁSQUEZ MANSILLA; HORACIO TROIANI; EMILIO DE BIASI; ROBERTO D. ZYSLER; DANIELA P. VALDÉS; LUIS RODRIGUEZ; DANIEL FREGENAL; GERARDO GOYA; TEOBALDO TORRES MOLINA

San Carlos de Bariloche

Simposio; XXIII Latin American Symposium on Solid State Physics (SLAFES XXIII); 2018

Organizing Committee

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 field with frequency between 100kHz and 1MHz. Ferrite nanoparticles are interesting systems for MFH whit 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 Znx Fe3−x O4 nanoparticles in order to understand their MFH response. By controlling the size and the composition of our samples we tune the effective magnetic anisotropy and the saturation magnetization, which allow us to optimize the SPA of our material in MFH experiments. MNPs of different sizes between 8-30nm where synthesized by high temperature thermal decomposition of organometallic precursors. The morphology of the nanoparticles 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, between 228 kHz and 817 kHz, and amplitude, up to 300 Oe, 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 magnetic relaxation of the nanoparticle´s moment and its phase shift respect to the ac applied field. With a simple model, we were able to analyse the dependence of the SPA with the frequency for the different 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.