Cerium doped superparamagnetic Mn-Zn ferrite particles as a promising material for self-regulated magnetic hyperthermia

Recently, cubic ferrites (CFs) have been widely explored in biomedical applications, especially those that display superparamagnetism behavior due to the desirable absence of a remanent field. In this study, we report the selfstabilization of the magnetic fluid hyperthermia (MFH) temperature in the cancer therapy range (42-48 degrees C) by Ce3+ substitution in superparamagnetic Mn0.8Zn0.2Fe2-xCexO4 ferrite particles with x = 0.0; 0.015; 0.030; 0.050 and 0.100. A comprehensive characterization was performed in order to investigate the influence of this replacement on the magnetic and structural properties of the ferrite. The samples were synthesized by the sol-gel auto-combustion method and the properties were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), Raman spectroscopy (RS), Mo<spacing diaeresis>ssbauer spectroscopy (MS), vibrational sample magnetometry (VSM), and ferromagnetic resonance (FMR). Magnetic hyperthermia essays were used to obtain the heat induction curves and calculate energy dissipation. We refined the XRD data by the Rietveld method to determine the cation distribution and calculate interionic parameters. Magnetic characterization confirms the superparamagnetic behavior at 300 K, which is expected from the TEM results that show a narrow distribution of particle sizes, with a mean size of about 6 nm for all samples. The VSM results show a consistent decrease in magnetization saturation with cerium content that leads to a weaker self-heating induction capacity for the cerium-doped samples. FMR results show a smaller relaxation time T2 for these samples, suggesting a slower energy dissipation rate. These conclusions are confirmed by the heat induction curves and the values of the specific absorption rate (SAR), which are smaller for cerium-doped samples. For themagnetic field with an amplitude of 35.33 kA/m and a frequency of 222 kHz, the temperature of the ceriumdoped samples saturates in the optimum interval for cancer treatment, between 42 and 48 degrees C. These results suggest that Ce3+ is a promising doping ion to optimize the heating rate behavior of Mn-Zn ferrite for cancer treatment by hyperthermia.