nanoparticles

The preparation of monodisperse magnetic nanoparticles has attracted much attention due to their potential applications in fields such as magnetic storage, drug targeting and delivery, cancer therapy and medical imaging [1]. For these last purposes well defined and water soluble magnetic nanocrystals are desired. By contrast, most of the approaches to obtain highly crystalline and monodisperse nanoparticles take place in organic media, providing particles with a hydrophobic surface. Thus, their transfer into aqueous media with a proper coating is a key issue for their application in areas such as biomedicine. In this contribution, we present the preparation, surface modification and characterization of gold coated Fe3O4 nanoparticles. Gold coated magnetite nanoparticles were synthesized by a two step procedure based on the polyol method [2]. The reduction of Au(OOCCH3)3 in the presence of the previously synthesized iron oxide seeds [3], yield gold coated nanoparticles of 5–7 nm, surrounded by organic ligands. The surface modification of the hydrophobic nanocrystals was performed by means of the amphiphilic poly(maleic anhydride-alt-1-octadecene) surfactant [4]. The hydrophobic regions of the polymer intercalates with the alkyl chains of oleic aci