Effect of applied magnetic field on permeability and heating efficiency of multifunctional micro/nano-magnetic particles for hyperthermia therapy

Hyperthermia using magnetic particles is a very promising cancer therapy. In previous studies, we developed a mixture of magnetic micro/nanoparticles with high heating efficiency for tumor treatment and considerable change in permeability around therapeutic temperature for monitoring its temperature and position during heating. In this study, we examined experimentally the effect of applied magnetic field on the heating and permeability properties of the proposed mixture by manipulating the amplitude and frequency (H = 1.8–7.1 kA/m, f = 500 kHz, and H = 4.8 kA/m, f = 200–1000 kHz). It was found that the specific absorption rate (SAR) of the mixture increased with the amplitude and frequency (SAR α H1.68×f). Its intensity of magnetization (μ0M) at 20°C changed linearly with the amplitude, whereas it remained almost unchanged with the frequency. The results obtained here may enable us to find the optimal conditions of the applied magnetic field and the amount of magnetic particles required to treat a tumor of a given size.