English Abstract
Abstract: Magnetite nanoparticles (MNPs) exhibit favorable heating responses under magnetic
excitation, which makes them particularly suited for various hyperthermia applications. Herein, we
report the detailed self-heating mechanisms of MNPs prepared via the Ko-precipitation Hydrolytic Basic
(KHB) methodology. The as-prepared MNPs were fully characterized using various spectroscopic
techniques including transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray
diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry
(VSM). MNPs exhibited stable 15 nm quasi-spherical small-sized particles, pure crystalline cubic
Fe3O4 phases, high saturation magnetizations (Ms = ~40 emu·g
−1
), and superparamagnetic behavior.
In response to alternating magnetic fields (AMFs), these MNPs displayed excellent self-heating
efficiencies with distinctive heating responses, even when minimal doses of MNPs were used.
Heating efficacies and specific absorption rate (SAR) values as functions of concentration, frequency,
and amplitude were systematically investigated. Remarkably, within only a few minutes, MNPs
(2.5 mg/mL) showed a rapid dissipation of heat energy, giving a maximum intrinsic loss power (ILP)
of 4.29 nHm2/kg and a SAR of 261 W/g. Hyperthermia temperatures were rapidly reached in as
early as 3 min and could rise up to 80 ◦C. In addition, Rietveld refinement, Langevin, and linear
response theory (LRT) models were studied to further assess the magnetic and heating mechanisms.
The LRT model was used to determine the Néel relaxation time (τR = 5.41 × 10−7
s), which was
compared to the Brownian relation time value (τB = 11 × 10−7
s), showing that both mechanisms
are responsible for heat dissipated by the MNPs. Finally, the cytotoxicity assay was conducted on
aqueous dispersions of MNPs, indicating their biocompatibility and low toxicity. Our results strongly
suggest that the as-prepared Fe3O4 MNPs are promising vehicles for potential magnetically triggered
biomedical hyperthermia applications
