Water Transfer of Magnetic Nanoparticles with Different Morphologies by Means of a Ligand Exchange Reaction with a Short-Chained Catechol Derivate

For many applications of magnetic nanoparticles, the material must be dispersed in water. Therefore, this study used a two-phase system to transfer iron oxide (gamma-Fe2O3 and Fe3O4) and iron platinum (FePt) nanoparticles to aqueous solution, using a low molecular weight catechol derivate (nitroDOPA). The monodisperse nanoparticles were synthesized in spherical and cubic shapes through high boiling point heat-up synthesis approaches followed by the phase transfer step. The colloidal nanoparticle solutions were investigated through infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and magnetometry measurements, giving a broad overview over the influence of the new catechol-ligand shell. It is shown that the nitroDOPA molecules bind through their catechol group on the surface of the magnetic nanoparticles, resulting in stable hydrophilic solutions under basic conditions. The physical properties of the magnetic nanoparticles were not altered by the ligand exchange reaction.