Facile Gold-Coated Maghemite Nanoparticles Fabrication

The maghemite (γ-Fe₂O₃) nanoparticles were obtained via high temperature pyrolysis with the precursor of magnetite that was synthesized via chemical coprecipitation. Then the (3-aminopropyl) triethoxysilane (APTES) was used for the surface functionalization of γ-Fe₂O₃ nanoparticles. Finally the gold-coated maghemite (γ-Fe₂O₃/Au) nanoparticles are prepared via sonochemical synthesis of a solution mixture of hydrochloroauric acid (HAuCl₄) and APTES-coated γ-Fe₂O₃ nanoparticles with further drop-addition of sodium citrate. The γ-Fe2O3/Au nanoparticles were characterized by X-ray powder diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM) and superconducting quantumn inteference devices (SQUID). The γ-Fe₂O₃/Au nanoparticles with double properties of magnetism and colloidal gold may have intensive application in immunology, biochemistry, biomedical and molecular biology.