The invention relates to nano-particles comprising metallic ferromagnetic nanocrystals combined with either amorphous or graphitic carbon in which or on which chemical groups are present that can dissociate in aqueous solutions.
According to the invention there is provided nano-particles comprising metal particles of at least one ferromagnetic metal, which metal particles are at least in part encapsulated by graphitic carbon.
The nano-particles of the invention are prepared by impregnating carbon containing bodies with an aqueous solution of at least one ferromagnetic metal precursor, drying the impregnated bodies, followed by heating the impregnated bodies in an inert and substantially oxygen-free atmosphere, thereby reducing the metal compounds to the corresponding metal or metal alloy.