Iron Oxide Nanospheres and Nanocubes for Magnetic Hyperthermia Therapy: A Comparative Study

Improving the heating capacity of magnetic nanoparticles (MNPs) for hyperthermia therapy is an important but challenging task. Through a comparative study of the inductive heating properties of spherical and cubic Fe3O4 MNPs with two distinct average volumes (similar to 7000 nm(3) and 80,000 nm(3)), we demonstrate that, for small size (similar to 7000 nm(3)), the cubic MNPs heat better compared with the spherical MNPs. However, the opposite trend is observed for larger size (similar to 80,000 nm(3)). The improvement in heating efficiency in cubic small-sized MNPs (similar to 7000 nm(3)) can be attributed to enhanced anisotropy and the formation of chain-like aggregates, whereas the decrease of the heating efficiency in cubic large-sized MNPs (similar to 80,000 nm(3)) has been attributed to stronger aggregation of particles. Physical motion is shown to contribute more to the heating efficiency in case of spherical than cubic MNPs, when dispersed in water. These findings are of crucial importance in understanding the role of shape anisotropy and optimizing the heating response of magnetic nano-structures for advanced hyperthermia.