Dependence of frequency and magnetic field on self-heating characteristics of NiFe2O4 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 2.8 degrees C to 72.6 degrees C by changing the applied frequency and magnetic field. The corresponding product of the frequency and the strength of magnetic field H(o)f was between 1.9 x 10(8) Am(-1)s(-1) and 13.4 x 10(8) Am(-1)s(-1). These values are in the biological safety and tolerable range for hyperthermia considering deleterious physiological response of human body during hyperthermia treatment.