Chitosan-Functionalized Lithium Iron Oxide Nanoparticles for Magnetic Hyperthermia Applications

Abstract

In this study, various compositions of α-Fe₂O₃, Li_3xFe_2-xO₃, where x = 0.1, 0.3, and 0.5, along with chitosan (CTS)-coated Li_1.5Fe_1.5O₃ nanomaterials (NMs), were synthesized using a sol-gel method. Rietveld refinement analysis indicated a predominance of the rhombohedral phase for lower Li-doped content (x = 0.1) and a transition to cubic crystal structures at higher Li-doped content (x = 0.3 and 0.5) within the host lattice. Field emission scanning electron microscopy (FE-SEM) images revealed irregular spherical morphologies, while transmission electron microscopy (TEM) images showed average particle sizes ranging from 19 to 40 nm across the various NMs. Superconducting quantum interference device (SQUID) analysis demonstrated a ferromagnetic nature with the highest saturation magnetization measured at 49.84 emu/g for Li_1.5Fe_1.5O₃ NMs. X-ray photoelectron spectra (XPS) exhibited Fe 2p_3/2 and Fe 2p_1/2 peaks at 712.60 and 726.13 eV, respectively, Li 1s at 57.58 eV, and O 1s at 533.44 eV for the representative samples; these characteristic XPS peaks shifted to a lower binding energy for CTS-coated Li_1.5Fe_1.5O₃ NMs. Hyperthermia studies demonstrated that the Li-doped samples reached a temperature range between 42 and 44 °C under an alternating current (AC) magnetic field applied at 167.6 to 335.2 Oe, with a constant frequency of 278 kHz. The specific absorption rate (SAR) was recorded as 265.11 W/g for Li_1.5Fe_1.5O₃ and 153.48 W/g for CTS-coated Li_1.5Fe_1.5O₃ NMs, both surpassing the SAR values of the other samples. Furthermore, various machine learning techniques were utilized to analyze how different synthesis conditions and material properties affected the heating efficiency and SAR values of the synthesized materials. The study also suggests an optimized set of guidelines and heuristics to enhance the heating performance and SAR values of these materials. Finally, magnetic CTS-coated Li_1.5Fe_1.5O₃ NMs exhibited a higher cell viability, as confirmed by MTT assays conducted on the NRK 52 E normal cell line.