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

ALMEIDA A.; WINKLER E.; LIMA JR. E.; VÁSQUEZ MANSILLA M.; TROIANI H.; DE BIASI E.; ZYSLER R.D.; VALDÉS D.P.; RODRIGUEZ L.; FREGENAL D.; GOYA G.; TORRES MOLINA T.

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

 Magnetic fluid hyperthermia (MFH) consists in theheating of a target tissue by the magnetic losses ofa ferro- or ferrimagnetic materials (MNPs) using acmagnetic field with frequency between 100kHz and1MHz. Ferrite nanoparticles are interesting systemsfor MFH whit a large number of potential applications in this field. The key parameter in MFH is thespecific power absorption (SPA) of the nanoparticles,and is determined by the magnetic, morphological andrheological properties of the solvent/MNPs. In thiswork, we present a study of the morphological andmagnetic properties of ZnxFe3!xO4 nanoparticles inorder to understand their MFH response. By controlling the size and the composition of our samples wetune the e↵ective magnetic anisotropy and the saturation magnetization, which allow us to optimize theSPA of our material in MFH experiments. MNPs ofdi↵erent sizes between 8-30nm where synthesized byhigh temperature thermal decomposition of organometallic precursors. The morphology of the nanoparticles was determined by TEM, the composition wasanalyzed by PIXE, and the magnetic properties weredetermined by magnetization measurements and ferromagnetic resonance experiments. The magnetic hyperthermia experiments were performed as a functionof both frequency, between 228 kHz and 817 kHz, andamplitude, up to 300 Oe, in di↵erent rheological conditions (i. e., di↵erent viscosities). The resulting SPAvalues were analyzed in terms of the di↵erent mechanisms that determine the magnetic losses. These mechanisms are related to the magnetic relaxation of thenanoparticle´s moment and its phase shift respect tothe ac applied field. With a simple model, we wereable to analyse the dependence of the SPA with thefrequency for the di↵erent samples. We also presentmeasurements of the catalytic peroxidase-like activityto produce free radicals of the nanoparticles underemulated physiological conditions, which is critical forpotential clinical uses of these systems.