Synthesis, characterization and magnetic hyperthermia properties of nearly monodisperse CoFe₂O₄ nanoparticles

In this study, the hyperthermia efficiency of CoFe₂O₄ nanoparticles (CFNPs) was enhanced by narrowing their size distribution and increasing their magnetic moment. The CFNPs were synthesized using the solvothermal reflux method. The NPs were crystallized in the face-centered cubic spinel structure (lattice parameter of 8.373 Å) and had a particle size of ~10 nm, as revealed by the X-ray diffraction and transmission electron microscopy (TEM) results, respectively. The high-resolution TEM images of the NPs revealed their single crystal nature. The infrared absorption bands above 700 cm⁻¹ confirmed the formation of octahedral and tetrahedral ligands on the surface of the NPs. The thermal analysis profiles of the synthesized NPs showed that the surface ligands decomposed at approximately 360 °C. The nanocolloids prepared using the NPs showed stable dispersion with a zeta potential of −17.7 mV. The X-ray photoelectron spectroscopy results revealed the presence of Co²⁺, Fe³⁺, and O²⁻ in the NPs. The NPs existed in the superparamagnetic state with a maximum mass magnetization of 71 emu g⁻¹, which is close to the theoretical value. The magnetic hyperthermia property of the NPs was investigated by determining their specific heat generation rate (SHGR) under biocompatible alternate magnetic field parameters. The NPs were capable of heating 185.32 W g⁻¹. This value is greater than the SHGR reported previously for CFNPs synthesized by other methods.