Solvothermal synthesis of CuFe2O4 and Fe3O4 nanoparticles with high heating efficiency for magnetic hyperthermia application

Magnetic nanoparticles with improved heating efficiency are required for an efficient magnetic hyperthermia therapy. In this study, monodisperse CuFe2O4 nanoparticles (NPs) with higher heat generation capability compared to Fe3O4 NPs were synthesized by a solvothermal method using triethylene glycol as solvent, reductant, and stabilizer. X-ray diffraction (XRD) analysis confirmed the single phase formation of CuFe2O4 and Fe3O4 NPs under experimental conditions. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of TREG molecules on the surface of both samples. Nanoparticles with spherical shape were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with an average particle size of 19.9 and 18.5 nm for CuFe2O4 and Fe3O4 NPs, respectively. The room temperature magnetic measurements indicated that both samples are in the vicinity of transition point from superparamagnetic to single-domain ferromagnetic state with a saturation magnetization of 53.1 and 58.8 emu/g for CuFe2O4 and Fe3O4 NPs, respectively. Moreover, CuFe2O4 NPs showed the lower anisotropy energy compared to Fe3O4 NPs, leading to the faster approach to saturation and slightly more rectangular hysteresis loop. The heating efficacy of the CuFe2O4 and Fe3O4 NPs were investigated under different safe alternating magnetic fields permissible for magnetic hyperthermia therapy (f = 120 kHz, H = 13, 16, and 19 kA/m). The maximum specific absorption rate (SAR) obtained for CuFe2O4 and Fe3O4 NPs were 44.9 and 18.5 W/g, respectively, at magnetic field intensity of 19 kA/m and frequency of 120 kHz. The two-fold increase in the SAR value of the CuFe2O4 NPs compared to the Fe3O4 NPs might be attributed to the tuning and better matching of their anisotropy energy with frequency and magnetic field intensity used in magnetic hyperthermia experiments.