The present invention relates to a system comprising magnetic nanoparticles of a metal oxide and a polymer, which in turn contains monomers with different functional groups. This system can be solid (nanocomposite) or liquid (ferrofluid). The present invention also relates to a process for obtaining the system, as well as its use, mainly in biotechnological, veterinary and medical applications, such as, for example, for the diagnosis and treatment of human diseases.
