High magnetic fluid hyperthermia efficiency in copper ferrite nanoparticles prepared by solvothermal and hydrothermal methods

Abstract

CuFe2O4 magnetic nanoparticles (MNPs) of two different morphologies and high magnetic heating efficiency are prepared using hydrothermal (CF) and solvothermal (CFPG) methods. Temperature dependent magnetization measurements indicate the presence of superparamagnetic phase at room temperature. The saturation magnetization for CFPG MNPs (~32.7 emu/g) is found to be ~ 31% higher than the CF MNPs, which is due to nearly collinear Neel type alignment of the magnetic moments in the tetrahedral and octahedral sites with a low Yafet-Kittel angle of ~ 5.980 and lower thickness of the magnetically disordered shell, which are confirmed from the cation distributions, non-zero spin canting angles and sub-spectral area analyses using low temperature (~5 K) in-field (~5 T) Mössbauer spectroscopy. The maximum specific absorption rate for CFPG MNPs is found to be ~ 192 ± 7 W/g, which is significantly higher than the previously reported values for copper ferrite MNPs. The high heating efficiency of CFPG MNPs is attributed to the near-resonant relaxation dynamics (ωτ ~ 1, where ω and τ indicate the angular frequency of the applied field and effective relaxation time, respectively). Heating efficiency is found to decrease with increasing sample concentration due to an enhancement in dipolar interactions, which is found to be in agreement with the quasi-static calculations. In vitro cytotoxicity studies indicate good bio-compatibility of the CFPG MNPs against human colon epithelial cells (HT-29) due to the presence of polyethylene glycol coating. The observed high heating efficiency along with negligible room temperature coercivity and superior bio-compatibility indicate the suitability of the solvothermally synthesized CuFe2O4 MNPs for magnetic fluid hyperthermia.