Research Abstract


Hyperthermic effects of dissipative structures of magnetic nanoparticles in large alternating magnetic fields

2011年11月15日 Scientific Reports 1 : 157 doi: 10.1038/srep00157


間宮 広明1 & Balachandran Jeyadevan2

  1. 独立行政法人 物質・材料研究機構 量子ビームセンター
  2. 滋賀県立大学 工学部
Targeted hyperthermia treatment using magnetic nanoparticles is a promising cancer therapy. However, the mechanisms of heat dissipation in the large alternating magnetic field used during such treatment have not been clarified. In this study, we numerically compared the magnetic loss in rotatable nanoparticles in aqueous media with that of non-rotatable nanoparticles anchored to localised structures. In the former, the relaxation loss in superparamagnetic nanoparticles has a secondary maximum because of slow rotation of the magnetic easy axis of each nanoparticle in the large field in addition to the known primary maximum caused by rapid Ne´el relaxation. Irradiation of rotatable ferromagnetic nanoparticles with a high-frequency axial field generates structures oriented in a longitudinal or planar direction irrespective of the free energy. Consequently, these dissipative structures significantly affect the conditions for maximum hysteresis loss. These findings shed new light on the design of targeted magnetic hyperthermia treatments.