Ferrimagnetic nanoparticles enhance microwave heating for tumor hyperthermia therapy

Localized tumor hyperthermia therapy has been intensively studied for the past three decades. One engineering limitation has been the difficulty of specifically targeting cancerous tissues in the normal tissue surroundings. Recent attention has turned to the deposition of nanoparticles in the tumor to enhance heating relative to its surroundings. The work in magnetic nanoparticles has focused on resonant hysteresis loop heating in the 100 to 300 kHz range, where that mechanism dominates-however extremely high magnetic field strengths are required to realize an advantage, up to 10⁵ (A/m). We introduce experimental evidence that substantial advantages in heating can also be obtained at the microwave ISM frequency of 2.45 GHz when γ-hematite (Fe₂O₃) is dispersed in media at concentrations on the order of 10¹² particles/mL.