Synthesis of Sub 3 nm-Sized Uniform Magnetite Nanoparticles Using Reverse Micelle Method for Biomedical Application

We report a synthetic method for small and uniform Fe₃O₄ (magnetite) nanoparticles under mild conditions. Spherical sub-3 nm-sized magnetite nanoparticles were prepared via reverse micelles composed of oleylamine, F127, xylene, and water for the reaction of iron(III) stearate with hydrazine at a reaction temperature of 90 °C in air atmosphere. These synthesized magnetite nanoparticles exhibited good size uniformity. By controlling experimental conditions, we could easily control both size and size uniformity of these magnetite nanoparticles. We further investigated whether Fe₃O₄ could be used in biomedical applications. Cytotoxicity of Fe₃O₄ was evaluated with human adipose-derived stem cells (hADSCs). Our results showed that the number of hADSCs did not significantly decrease when these cells were treated with Fe₃O₄ nanoparticles at a concentration of up to 9 μg/mL. Apoptotic activity and cell proliferation of hADSCs treated with Fe₃O₄ nanoparticles were similar to those of hADSCs without any treatment. This novel method could be used for synthesizing uniform and biocompatible Fe₃O₄ nanoparticles with further biomedical applications.