SYNTHESIS AND CHARACTERIZATION OF SILICA COATED MAGNETIC IRON OXIDE NANOPARTICLES
Authors: Nguyen-Le Minh-Tri , Nguyen Dinh Tien Dung , Rich Sophia , Nguyen Ngoc Tram , Nguyen Cuu Khoa , Nguyen Dai Hai 
Published: October 2019

Advances in nanotechnology in recent years has led to a number of diverse applications of nanomaterials. Magnetic iron oxide nanoparticles (Fe3O4 NPs), a representative of magnetic nanomaterials, has gained much attention of many researchers all over the world due to their unique properties such as superparamagnetism, biocompatibility and high magnetic saturation. With such properties, Fe3O4 NPs can be exploited in many fields, particularly biomedicine related fields such as cellular therapy, tissue repair, drug delivery, magnetic resonance imaging, hyperthermia and magnetofection. However, owing to their self-aggregation of Fe3O4 NPs, it is necessary to coat Fe3O4 NPs with a stable and biocompatible silica layer. Therefore, in this report, Fe3O4 NPs were synthesized via a co-precipitation method using iron (II)/ iron (III) chloride, ammonia and trisodium citrate. Then, the silica layer was coated onto Fe3O4 NPs through the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in ethanol. The as-synthesized samples were charaterized with the infrared (IR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results proved that silica was successfully coated on Fe3O4 NPs. The particle sizes measured by TEM were found to be about 12 nm in diameter for Fe3O4 NPs and 45 nm in diameter for silica coated Fe3O4 (SiO2@Fe3O4) NPs, while the dynamic diameters measured by DLS for Fe3O4 NPs and SiO2@Fe3O4 NPs were 15.7 and 65.8 nm, respectively. Both Fe3O4 NPs and SiO2@Fe3O4 NPs were superparamagnetic materials in which Fe3O4 NPs have higher magnetic saturation (45.8 emu/g) than the other (13.4 emu/g).This study examines the: ……...Advances in nanotechnology in recent years has led to a number of diverse applications of nanomaterials. Magnetic iron oxide nanoparticles (Fe3O4 NPs), a representative of magnetic nanomaterials, has gained much attention of many researchers all over the world due to their unique properties such as superparamagnetism, biocompatibility and high magnetic saturation. With such properties, Fe3O4 NPs can be exploited in many fields, particularly biomedicine related fields such as cellular therapy, tissue repair, drug delivery, magnetic resonance imaging, hyperthermia and magnetofection. However, owing to their self-aggregation of Fe3O4 NPs, it is necessary to coat Fe3O4 NPs with a stable and biocompatible silica layer. Therefore, in this report, Fe3O4 NPs were synthesized via a co-precipitation method using iron (II)/ iron (III) chloride, ammonia and trisodium citrate. Then, the silica layer was coated onto Fe3O4 NPs through the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in ethanol. The as-synthesized samples were charaterized with the infrared (IR) spectroscopy, X-ray diffraction (XRD) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results proved that silica was successfully coated on Fe3O4 NPs. The particle sizes measured by TEM were found to be about 12 nm in diameter for Fe3O4 NPs and 45 nm in diameter for silica coated Fe3O4 (SiO2@Fe3O4) NPs, while the dynamic diameters measured by DLS for Fe3O4 NPs and SiO2@Fe3O4 NPs were 15.7 and 65.8 nm, respectively. Both Fe3O4 NPs and SiO2@Fe3O4 NPs were superparamagnetic materials in which Fe3O4 NPs have higher magnetic saturation (45.8 emu/g) than the other (13.4 emu/g).