Heat dissipation mechanism of magnetite nanoparticles in magnetic fluid hyperthermia

The relative contributions of Néel and Brownian relaxations on magnetic heat dissipation were studied by investigating the physical, magnetic and heating characteristics of magnetite nanoparticle suspensions with average diameters of 12.5 and 15.7 nm. Heating characteristics depended on the dispersion states of particles. The specific absorption rates (SAR) dropped by 27% for the 12.5 nm particles to 16.8×10−9 W g−1 Oe−2 Hz−1 and by 67% for the 15.7 nm particles to 9.69×10−9 W g−1 Oe−2 Hz−1, when the particle rotation was suppressed by dispersing magnetite nanoparticles in hydro-gel.