Nanostructures displaying fluorescence and magnetic properties at the same time are potentially useful for achieving simultaneous bio-sepn. and bio-sensing (e.g., magnetic sepn. coupled with multiplexing optical detection of different tumor cell populations). Spherical nanobeads that display both fluorescent and magnetic features are reported; they are fabricated by grafting fluorescent oligothiophene mols. to an amphiphilic polymer that is then used to enwrap iron oxide nanoparticles, which acts as the magnetic domain. By tuning exptl. conditions, control over the no. of magnetic nanoparticles per bead and over the bead diam. (30-400 nm) was achieved. A cell sepn. efficiency of the level required for cell sorting applications is also reported.