Factors affecting the measurement of magnetic hyperthermia

Traditional methods for cancer treatment are based on the unspecific death of cancerous cells using drugs or highly energetic radiation which cause drastic side effects. Magnetic hyperthermia has been shown to have no known side effects and will allow for reduced doses and even replacement of those more conventional treatments. Currently, only magnetite (Fe₃O₄) / maghemite (g-Fe₂O₃) nanoparticles have been approved for use in humans. In most studies of magnetic hyperthermia the value of the anisotropy constant is assumed to be uniform although a distribution will occur. This is due to the fact that the anisotropy of magnetite/maghemite nanoparticles is dominated by shape. For example a change in the aspect ratio from 1.1 to 1.5 varies the shape anisotropy constant by 300%. This is critical as in most experimental studies particles have elongation ratios in that range. Both calculations and experimental results will be presented highlighting the importance of taking into account the distribution of anisotropy constants