An approach using physical vapor deposition technology to produce nanoparticles (NPs) containing radioactive atoms and the methodology to transfer them in pure water is investigated. NPs are synthesized by magnetron sputtering at high pressure and radioactive atoms are loaded on magnetron cathodes prior to sputtering. The technique was tested for gold cathode loaded with Co and Au. Linked to biological vector molecules, the nanoparticles can be used to enhance diagnostic sensitivity in medical imaging or to treat cancer.Sizes and morphologies of the NPs were analyzed by electron microscopy, UV-Visible spectroscopy and atomic absorption spectroscopy. Results show well dispersed NPs with sizes varying between 5 and 10. nm. Activities of these NPs were measured with a CAPINTEC well counter and a High Purity Germanium detector system. Centrifugation analyses also demonstrate that the choice of the activated metal which can be alloyed with NPs plays an important role in the synthesis. This was confirmed by the Au-Co phase diagram that shows that cobalt cannot be included efficiently in the gold NPs conversely to gold. © 2011 Elsevier B.V.