MagDot is a dual-purpose reagent, it combines quantum dots and superparamagnetic iron oxide particles within the same nanoparticle. MagDots modified with  streptavidin have been developed for magnetic labeling and separation of cells or other biological materials that are labeled with a biotinylated primary antibody. Cells labeled with will be both fluorescent and magnetic allowing one to perform a bulk magnetic cell enrichment or depletion and then go straight to fluorescence analysis