Role of Gd3+ substitution on magnetic properties and enhancement of self-heating ability of Fe3O4 nanoparticles for magnetic hyperthermia application

Abstract

Magnetic hyperthermia is an emerging modality for cancer treatment that offers significant potential due to its non-invasive and localized thermal ablation capability. Superparamagnetic iron oxide nanoparticles generate heat when subjected to alternating magnetic field, making them suitable for hyperthermia applications. However, achieving the desired hyperthermic temperature within a short time frame remains a significant challenge. In this study, Fe₃O₄ nanoparticles were doped with varying concentrations of Gd³⁺ ions (0%, 2%, 5%, and 10%) using a simple co-precipitation method to enhance heating efficiency. X-ray diffraction analysis confirmed the formation of single-phase inverse spinel structures with an average crystallite size ranging from 10 nm to 14 nm. Magnetic measurements revealed a reduction in saturation magnetization (M_S) from 61 emu/g for undoped Fe₃O₄ to 43 emu/g for the 10% Gd-doped sample, attributed to antiferromagnetic coupling between Gd³⁺ and Fe³⁺ ions. Electron spin resonance studies indicated reduced dipole–dipole interactions in the doped samples, contributing to enhanced heating performance. Calorimetric evaluations under an alternating magnetic field of 8 kA/m at 500 kHz demonstrated superior heating efficiency for the 10% Gd-doped sample, with a specific absorption rate of 20.25 W/g and an effective specific absorption rate of 0.63 nHm²kg⁻¹, significantly outperforming undoped Fe₃O₄ with specific absorption rate of 3.49 W/g, effective specific absorption rate of 0.11 nHm²kg⁻¹. Notably, all samples reached therapeutic temperatures within 60 s, minimizing exposure time. These findings highlight Gd-doped Fe₃O₄ nanoparticles as promising candidates for efficient and rapid-response magnetic hyperthermia within clinically safe external parameters.