Ferromagnetic nanoparticles for magnetic hyperthermia and thermoablation therapy

The use of ferromagnetic nanoparticles for hyperthermia and thermoablation therapies has shown great promise in the field of nanobiomedicine. Even local hyperthermia offers numerous advantages as a novel cancer therapy; however, it requires a remarkably high heating power of more than 1 kW g(-1) for heat agents. As a candidate for high heat generation, we focus on ferromagnetic nanoparticles and compare their physical properties with those of superparamagnetic substances. Numerical simulations for ideal single-domain ferromagnetic nanoparticles with cubic and uniaxial magnetic symmetries were carried out and MH curves together with minor loops were obtained. From the simulation, the efficient use of an alternating magnetic field (AMF) having a limited amplitude was discussed. Co-ferrite nanoparticles with various magnitudes of coercive force were produced by co-precipitation and a hydrothermal process. A maximum specific loss power of 420 W g(-1) was obtained using an AMF at 117 kHz with H-0 = 51.4 kA m(-1) (640 Oe). The relaxation behaviour in the ferromagnetic state below the superparamagnetic blocking temperature was examined by Mossbauer spectroscopy.