Hyaluronic acid-coated iron oxide nanoparticles for magnetic fluid hyperthermia and methylene blue dye removal: Preparation, physicochemical characterization, and enhancing the heating efficiency

We report here the magnetic fluid hyperthermia properties of water-dispersible hyaluronic acid-coated superparamagnetic iron oxide nanoparticles (HA-MNPs), prepared using the coprecipitation technique followed by ligand exchange. The presence of the hyaluronic acid coating is confirmed using Fourier transform infrared spectroscopy. Magneto-calorimetric studies show good field-induced heating efficiency of the HA-MNPs, where a high specific absorption rate (SAR) of ∼ 315 W/gFe is obtained for ∼ 5 wt% MNP concentration when exposed to an alternating magnetic field amplitude of ∼ 33.1 kA/m at ∼ 126 kHz. The heating efficiency is found to decrease by ∼ 33.8 % after immobilization of the MNPs within an agar matrix, which is attributed to the abrogation of Brownian relaxation. When subjected to an external DC magnetic field, the MNPs form linear chain-like structures, which causes the effective anisotropy energy density to increase. Magneto-calorimetric studies on agar-based oriented samples reveal a ∼ 19.5 % enhancement in SAR, thereby partly compensating for the loss in heating efficiency due to an increase in medium viscosity. The orientational ordering-induced enhancement in SAR is also verified using sweeping rate modified Stoner-Wohlfarth model-based calculations. In vitro cyto-toxicity studies on the HeLa cell lines reveal good cyto-compatibility of the MNPs. The negative charge on the surface of HA-coated MNPs is exploited to remove the cationic methylene blue dye from the aqueous medium, where the dye molecules are found to be physisorbed on the surface of the MNPs. The experimental findings clearly show the high induction heating efficiency, cyto-compatibility, and cationic dye-adsorption efficiency of the prepared HA-MNPs, thereby indicating the suitability of these MNPs for multi-functional applications like magnetic fluid hyperthermia and waste-water purification. © 2024 Elsevier B.V.