Cubic and Sphere Magnetic Nanoparticles for Magnetic Hyperthermia Therapy: Computational Results.

Magnetic nanoparticles (MNPs) with various shapes and special (magnetic and thermal) properties are promising for magnetic hyperthermia. The efficiency of this therapy depends mainly on the MNPs' physical characteristics: types, sizes and shapes. This paper presents the hyperthermic temperature values induced by cubic/sphere-shaped MNPs injected within a concentric tissue configuration (malignant and healthy tissues) when an external time-dependent magnetic field was applied. The space-time distribution of the nanoparticles as a result of their injection within a tumoral (benign/malign) tissue was simulated with the bioheat transport equation (Pennes equation). A complex thermo-fluid model that considers the space-time MNP transport and its heating was developed in Comsol Multiphysics. The cubic-shaped MNPs give a larger spatial distribution of the therapeutic temperature in the tumoral volume compared to the spherical-shaped ones. MNP doses that induce the therapeutic (hyperthermic) values of the temperature (40 ÷ 45 °C) in smaller volumes from the tumoral region were analyzed. The size of these regions (covered by the hyperthermic temperature values) was computed for different magnetite cubic/sphere-shaped MNP doses. Lower doses of the cubic-shaped MNPs give the hyperthermic values of the temperature in a larger volume from the tumoral region compared with the spheric-shaped MNPs. The MNP doses were expressed as a ratio between mass concentration and the maximum clinical accepted doses. This thermo-fluid analysis is an important computational instrument that allows the computations of the MNP doses that give therapeutic temperature values within tissues.