Physicochemical characterization of Fe3O4/SiO2/Au multilayer nanostructure

Abstract

The purpose of this research was to synthesize and characterize gold-coated Fe3O4/SiO2 nanoshells for biomedical applications. Magnetite nanoparticles (NPs) were prepared using co-precipitation method. Smaller particles were synthesized by decreasing the NaOH concentration, which in our case this corresponded to 35nm using 0.9M of NaOH at 750rpm with a specific surface area of 41m2g−1. For uncoated Fe3O4 NPs, the results showed an octahedral geometry with saturation magnetization range of 80–100emug−1 and coercivity of 80–120 Oe for particles between 35 and 96nm, respectively. The magnetic NPs were modified with a thin layer of silica using Stober method. Small gold colloids (1–3nm) were synthesized using Duff method and covered the amino functionalized particle surface. Magnetic and optical properties of gold nanoshells were assessed using Brunauer–Emmett–Teller (BET), vibrating sample magnetometer (VSM), UV–Vis spectrophotometer, atomic and magnetic force microscope (AFM, MFM), and transmission electron microscope (TEM). Based on the X-ray diffraction (XRD) results, three main peaks of Au (111), (200) and (220) were identified. The formation of each layer of a nanoshell is also demonstrated by Fourier transform infrared (FTIR) results. The Fe3O4/SiO2/Au nanostructures, with 85nm as particle size, exhibited an absorption peak at ∼550nm with a magnetization value of 1.3emug−1 with a specific surface area of 71m2g−1.