Multifunctional nanoprobes combining magnetic nanoparticles with organic dyes have attracted tremendous interest due to their promising applications in biomedical field. Here we demonstrate a facile and general strategy for the fabrication of robust fluorescent magnetic nanoprobes with high payloads of dye molecules and their use as multimodal nanoprobes for cell imaging. These nanoprobes not only effectively keep photochemical stability of dyes, but also provide a platform for grafting other functional or targeted moieties into silica surface via primary amines. Moreover, the nanoprobes are uniformly spherical morphology and can be dispersed well in aqueous solution, which are very desirable for biomedical applications. Importantly, this method can be extended to synthesize other bifunctional nanoprobes by using the dyes with isothiocyanate group. (C) 2010 Elsevier Inc. All rights reserved.