OICC Press International Nano Letters 2228-5326 3 1 (December 2013) 2013 04 15 Surface modification of Fe3O4@SiO2 microsphere by silane coupling agent 10.1186/2228-5326-3-23 EN Fatemeh Ahangaran Department of Chemistry, Faculty of Science, Urmia University, Urmia, IR Ali Hassanzadeh Department of Chemistry, Faculty of Science, Urmia University, Urmia, IR Nanotechnology Research Center of Urmia University, Urmia, IR Sirous Nouri Department of Chemistry, Faculty of Science, Urmia University, Urmia, IR Journal Article 2013 04 15 Abstract In the present study, Fe 3 O 4 @SiO 2 core–shell microspheres were prepared via two steps. First, Fe 3 O 4 nanoparticles were synthesized by co-precipitation of Fe +3 and Fe +2 as reaction substrates and NaOH as precipitant. Second, the surface of Fe 3 O 4 was coated with silica by hydrolysis of tetraethylorthosilicate as the silica source. Subsequently, in order to reduce the amount of interaction and the agglomeration of Fe 3 O 4 @SiO 2 microspheres, the silica shell of these particles was modified by vinyltriethoxysilane as the silane coupling agent. The structural properties of the samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy analyses. The results indicated that the average sizes of Fe 3 O 4 and Fe 3 O 4 @SiO 2 particles were about 50 and 500 nm, respectively. Also, the surface characterization of Fe 3 O 4 @SiO 2 microspheres showed that the silane coupling agent was covalently coupled with the silica surface.