Laser and Nanobiophotonic Lab., Biomaterials Group, Faculty of Biomed. Eng., Amir Kabir University of Technology, Tehran, I.R. Iran
The main objective of this research was to synthesize and characterize gold-coated Fe3O4 /SiO2 nanoshells for clinical applications. Magnetite nanoparticles (NPs) were prepared via co-precipitation. The results showed that smaller particles can be synthesized by decreasing the NaOH concentration, which in our case this corresponded to 35 nm by using 0.9 M of NaOH at 750 rpm. The NPs were then modified with a thin layer of silica using Stober method. The surface of Fe3O4 /SiO2 nanoshells was then terminated with amine groups with 3-aminopropyltriethoxysilane (APTS) in ethanol. Small gold colloid (1-3 nm) were adsorbed on the particle surface via the interaction between the negative charge on the Au nanoparticles and the positive charge of -NH3 on the SiO2 shell modified by APTS. Gold nanoshell formation, morphology and dimensions were assessed with a UV-Vis spectrophotometer, atomic force microscope (AFM), and transmission electron microscope (TEM). The synthesized nanostructures exhibited an absorption peak at ~550 nm with a magnetization value of 1.3 emu/g. Based on the X-ray diffraction (XRD) results, three main peaks of Au were identified. The formation of each layer of a nanoshell is also demonstrated by Fourier transform infrared (FTIR) results.