Hyperthermia properties of Ni_xFe_3−xO₄ nanoparticles: a first-order reversal curve investigation

Magnetic nanoparticles (NPs) studied in hyperthermia investigations have shown promising results in combating tumors and slowing cancerous growth. However, no attention has been paid to hyperthermia properties of nickel ferrite NPs with different compositions. Herein, we synthesize Ni_xFe_3−xO₄ (0 ≤ x ≤ 1) NPs using a co-precipitation method, followed by the investigation of their structural, magnetic, and hyperthermia properties. According to room-temperature hysteresis loop results, the complete replacement of Fe cations by Ni²⁺ ions leads to a reduction in the saturation magnetization (M_s) from 55.40 to 19.30 emu/g, and an increase in the coercive field (H_c) from 7.33 to 71.40 Oe. Moreover, first-order reversal curve analysis reveals a reduction in the respective superparamagnetic fraction from 77 to 29% when increasing the Ni concentration (x) from 0 to 1. The results on magnetic hyperthermia properties show that Ni_0.6Fe_2.4O₄ and Ni_0.8Fe_2.2O₄ NPs have highest heating efficiency, giving rise to specific loss power values of 170.5 and 169 W/g in a water medium with a concentration of 3 mg/ml, and 200.5 and 198.4 W/g for a concentration of 1.5 mg/ml, respectively.