A novel method for the preparation of stable bilayer-coated magnetite particles for hyperthermia

Stable water-based magnetic fluids were synthesized by a sequential process involving the co-precipitation of Fe3* and Fe2+ with NH3H2O to prepare magnetic particles, then two stabilizers, sodium oleate (SO) and Dextran T-40, were used to coat the particles. The prepared magnetic particles were stabilized against agglomeration by the bilayer structure formed by SO, as an inner layer, adsorbed firmly onto the surface of the magnetic particles by hydrogen bonding, and dextran T-40, as an outer layer, interacted with SO in the same way, which were confirmed by Fourier transform infrared (FT-IR). The particle morphology and size were characterized using transmission electron microscopy (TEM), indicating the formation of single-domain nanoparticles with a mean diameter of about 26.1 nm. The saturation magnetization (Ms) value of 42.1 emu/g was obtained by vibrating sample magnetometry (VSM). Also, X-ray powder diffraction (XRD) analysis showed that the powder phase was almost entirely magnetite. The bilayer-coated magnetic fluid can be used as a therapeutic agent to release thermal energy as determined in hyperthermic tests.