Magnetic Hyperthermia With Fe3O4 Nanoparticles: The Influence of Particle Size on Energy Absorption.

We have studied the magnetic and power absorption properties of a series of magnetic nanoparticles (MNPs) of Fe3O4 with average sizes (d) ranging from 3 to 26 nm. Heating experiments as a function of particle size revealed a strong increase in the specific power absorption (SPA) values for particles with (d) = 25-30 nm. On the other side saturation magnetization Ms values of these MNPs remain essentially constant for particles with (d) above 10 nm, suggesting that the absorption mechanism is not determined by Ms. The largest SPA value obtained was 130 W/g, corresponding to a bimodal particle distribution with average size values of 17 and 26 nm. [ABSTRACT FROM AUTHOR]