Synthesis and functionalization of SiO2 coated Fe3O4 nanoparticles with amine groups based on self-assembly

The purpose of this research was to synthesize amino modified Fe3O4/SiO2 nanoshells for biomedical applications. Magnetic iron-oxide nanoparticles (NPs) were prepared via co-precipitation. The NPs were then modified with a thin layer of amorphous silica. The particle surface was then terminated with amine groups. The results showed that smaller particles can be synthesized by decreasing the NaOH concentration, which in our case this corresponded to 35 nm using 0.9 M of NaOH at 750 rpm with a specific surface area of 41 m(2) g(-1) for uncoated Fe3O4 NPs and it increased to about 208 m(2) g(-1) for 3-aminopropyltriethoxysilane (APTS) coated Fe3O4/SiO2 NPs. The total thickness and the structure of core-shell was measured and studied by transmission electron microscopy (TEM). For uncoated Fe3O4 NPs, the results showed an octahedral geometry with saturation magnetization range of (80-100) emu g(-1) and coercivity of (80-120) Oe for particles between (35-96) nm, respectively. The Fe3O4/SiO2 NPs with 50 nm as particle size, demonstrated a magnetization value of 30 emu g(-1). The stable magnetic fluid contained well-dispersed Fe3O4/SiO2/APTS nanoshells which indicated monodispersity and fast magnetic response. (C) 2011 Elsevier B.V. All rights reserved.