Influence of media type on heating of selected magnetic nanoparticles with time-harmonic magnetic fields

Hyperthermia is already well established in cancer treatment as a sensitizer to radiotherapy and chemotherapy. It is based on heating of tumor area to temperatures between 41 and 45°C. Usually it is induced by electromagnetic or ultrasound waves. In both cases selective heating of the treated area is accomplished by superposition of fields and is due to physical and technical limitations a challenging task. A very promising concept for preferential heating of the tumor area is based on accumulation of magnetic nanoparticles in the tumor and heating them with time-harmonic magnetic fields. In this work we use 1 ml sample of four different magnetic nanoparticles with different cores and coatings dispersed in PBS and deionized water. The individual samples were exposed to a time-harmonic magnetic field and the sample temperature was monitored throughout the exposure. The concentration of nanoparticles in the samples was chosen to correspond to realistic values that may be present in biological tissues without being toxic. For this purpose, we designed and manufactured an exposure system operating at 200 kHz. The exposure time was set to 5 minutes and the amplitude of the applied magnetic field intensity was up to 5 kA ·m_1. The temperature was monitored by an optical thermometer. Temperature measurements indicated the possibility to exert effective increase of temperature during the time period indicated in samples with nanoparticles dispersed in deionized water. In this paper we will introduce the exposure system as well as some results.