Dependence of Frequency and Magnetic Field on Self-Heating Characteristics of NiFe$_2$O$_4$Nanoparticles for Hyperthermia

Self-heating temperature-rising characteristics of nano-size controlled NiFe2O4 particles were analyzed as a function of applied frequency and magnetic field in order to investigate the physical principle of self-heating and to confirm the possibility for a real in vivo hyperthermia application. According to the magnetic properties of 35-nm size NiFe2O4 nanoparticles, it was confirmed that the physical mechanism of self-heating is mainly attributed to the hysteresis loss. In addition, it was found that the self-heating temperature was linearly increased by increasing frequency and was proportionally square to the applied magnetic field. The self-heating temperature was rapidly increased in an initial stage and then it reached to the maximum. The maximum self-heating temperature was controlled from 2.8degC to 72.6degC by changing the applied frequency and magnetic field. The corresponding product of the frequency and the strength of magnetic field H0f was between 1.9times108 Am-1s-1 and 13.4times10 8 Am-1s-1. These values are in the biological safety and tolerable range for hyperthermia considering deleterious physiological response of human body during hyperthermia treatment