Large-scale Fe3O4 nanoparticles soluble in water synthesized by a facile method

Large-scale hydrophilic Fe3O4 nanoparticles (NPs) were prepared in the presence of citrate and sodium nitrate via a facile method. The Fe3O4 NPs are quite stable and can be freely dispersed in water. The as-prepared magnetic nanoparticle solution can be stable for more than I month. The mean diameter of the Fe3O4 NPs can be controlled in the range of similar to 20 to similar to 40 nm in mean diameter. The NPs show superparamagnetic properties with a relatively high saturation magnetization moment 58 emu/mg at room temperature. Furthermore, a possible formation mechanism is proposed to explain why the magnetic nanoparticles are very well soluble in water.