Synthesis and characterization of Fe₃O₄＠SiO₂ magnetic-fluorescent bifunctional nanoparticles

Fe₃O₄＠SiO₂ nanoparticles were prepared by way of combining organic template and reverse micro-emulsion,and Fe₃O₄ nanoparticles were covered by silica layers with core-shell morphologies.Then fluorescein 5-isothiocyanate (FITC) was chemically attached onto the nanoparticles by 3-aminopropyl-triethoxysilane (APTES),realizing Fe₃O₄＠SiO₂(FITC) nanoparticles with the dual functions of the magnetic and fluorescence.We prepared SiO₂(RITC) nanoparticles incorporating covalently with rhodamine B isothiocyanate (RITC) as control for magnetic separation experiments.The Fe₃O₄＠SiO₂(FITC) nanoparticles were then characterized by Fourier transform infrared (FT-IR) spectrometry,X-ray diffraction (XRD),transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) techniques.Results showed that the average diameter of nanoparticles was about 100 nm,and the saturation magnetization was 29.8 emu/g,which exhibited superparamagnetic behavior and high fluorescent intensity.The fluorescent microscopic observations showed that Fe₃O₄＠SiO₂(FITC) had both magnetic and fluorescent properties with a good separation effect.