The invention provides nanoparticles consisting of a polymer which is a metal chelating agent coated with a magnetic metal oxide, wherein at least one active agent is covalently bound to the polymer, said nanoparticles may optionally further comprise at least one active agent physically or covalently bound to the outer surface of the magnetic metal oxide. Pharmaceutical compositions comprising these nanoparticles may be used, inter alia, for detection and treatment of tumors and inflammations.
