Synthesis and characterisation of magnetic-fluorescent Fe3O4@SiO2@ZnS nanocomposites

Bifunctional magnetic-fluorescent Fe₃O₄@SiO₂@ZnS nanocomposites were synthesised by a chemical deposition method. The Fe₃O₄ magnetic nanoparticles as the core were obtained by means of a solvothermal reaction with SiO₂ as the shell. ZnS particles were linked to Fe₃O₄@SiO₂ core-shell nanostructures. The morphology and properties of the resultant Fe₃O₄@SiO₂@ZnS nanocomposites were investigated by X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, a vibration sample magnetometer and fluorescence microscopy. The results showed that bead-like structures were built from numerous Fe₃O₄@SiO₂@ZnS microspheres with an average size of 250 nm. The saturation magnetisation (M_s) value of Fe₃O₄@SiO₂@ZnS nanocomposites was 22.41 emu/g at room temperature. Furthermore, a strong blue light emission was observed from the nanocomposites under UV light irradiation. The combination of magnetic and fluorescent properties may lead to Fe₃O₄@SiO₂@ZnS nanocomposites having a variety of potential applications in the field of biomedicine, such as bioimaging and cell separation.