Effect of manganese ion doping on magnetic properties and magnetic induction heating of Zn-Al ferrite nanoparticles

Magnetic induction hyperthermia (MIH) is a new kind of cancer treatment that preferentially targets tumor cells due to their poor heat resistance. In recent years, ferrite magnetic nanoparticles with spinel structures that can self-regulate the temperature of hyperthermia have been widely used in MIH. Importantly, substituting ions with different magnetic moments in magnetic nanoparticles can effectively regulate their Curie temperature and heating efficiency. Here we investigate the influence of Mn2+ doping on the magnetic properties, Curie temperature, and the heating efficiency of hydrothermally synthesized MnxZn1-xAl0.4Fe1.6O4 (0.4 ≤ x ≤ 0.8) nanoparticles. With increasing substitution of Zn2+ content by Mn2+, the mass magnetization increases from 30.2 to 54.2 emu g−1, the Curie temperature increases from 47.5 to 257.8 ℃, and the heating efficiency (specific loss power, SLP) increases from 6.3 to 54.5 W g−1, respectively. Of note, aqueous suspensions of Mn0.5Zn0.5Al0.4Fe1.6O4 nanoparticles demonstrate self-regulated temperature hyperthermia at 45.4 ℃ in vitro with the SLP of 11.1 W g−1 under clinically safe alternating magnetic field, manifesting a combination of high heating efficiency and clinically desirable therapeutic temperature. This study provides a new class of magnetic nanoparticles potentially useful for fast and safe MIH for cancer treatment.