Magnetic hyperthermia properties of CoFe₂O₄ nanoparticles: Effect of polymer coating and interparticle interactions

In this work, CoFe(2)O(4 )magnetic nanoparticles (MNPs) were synthesized by an eco-friendly co-precipitation method. The effect of Triethylene glycol (TEG) coating on the structural, magnetic and magnetothermal prop-erties of MNPs was investigated. The formation of crystalline MNPs with a cubic spinel structure and the single phase state was confirmed by the X-ray diffraction (XRD) and infrared spectra (FT-IR) techniques. The spherical morphology and aggregation of the MNPs, as a sign of the presence of interparticle interactions, were revealed by the field emission scanning electron microscopy imaging. A remarkable result has been found by the SQUID and Mo spacing diaeresis ssbauer spectroscopy measurements revealing that the polymer coating increases the saturation magnetiza-tion through the control of the metal-oxygen-metal bonds and reduction of the spin disorder at the nanoparticle surface. Furthermore, the Henkel plots indicated a dominant role of the dipole-dipole over exchange magnetic interactions in the samples which affected the heating efficiency of the ferrofluids measured under different AC magnetic fields (2.2, 2.7, and 3.3 mT) with a frequency of 92 kHz showing a linear dependence of the thermal efficiency with the AC field amplitude. It was shown that TEG coating increases the heating efficiency of the CoFe(2)O(4 )MNPs, which was attributed to an increase in saturation magnetization and a decrease in the strength of the magnetic interactions between the coated nanoparticles.