A new CoFe(2)O(4)-Cr(2)O(3)-SiO(2) fluorescent magnetic nanocomposite.

A combined sonochemical co-precipitaion method has been developed for the synthesis of a CoFe(2)O(4)-Cr(2)O(3)-SiO(2) magnetic nanocomposite. The synthesis involved the pre-synthesis of CoFe(2)O(4)-Cr(2)O(3) nanoparticles, which were subsequently coated with SiO(2) by treatment with tetraethyl orthosilicate. It was observed that the as-prepared CoFe(2)O(4)-Cr(2)O(3)-SiO(2) nanocomposite exhibits photoluminescence properties without the addition of any external fluorescent marker. The fluorescent magnetic nanoparticles (FMNPs) had a typical diameter of 30 ± 5 nm and a saturation magnetization of 5.1 emu g(-1) at room temperature. This as-prepared nanocomposite was used for staining cultured HeLa cells for fluorescence imaging.