Synthesis of ε-Fe_2-3N Particles for Magnetic Hyperthermia

Little research has focused on using iron nitride as thermoseed particles in magnetic hyperthermia, although magnetite (Fe₃O₄) is commonly used for this purpose. In the present study, we focus on iron nitride, especially ε-Fe_2-3N. ε-Fe_2-3N particles were synthesized from hematite (α-Fe₂O₃) and sodium amide (NaNH₂) under various synthesis conditions, and the heat-generation properties of the particles were investigated to reveal the synthesis conditions that lead to particles with notable heat-generation performance. The particles synthesized at 250 °C for 12 h increased the temperature of an agar phantom by approximately 20 °C under an alternating magnetic field (100 kHz, 125 Oe, 600 s), suggesting that ε-Fe_2-3N particles can be used for magnetic hyperthermia. The analysis results for the particles synthesized under different conditions suggest that the heat-generation properties of ε-Fe_2-3N were affected by several factors, including the nitrogen content, particle size, crystallite size, saturation magnetization, and coercive force.