Preparation of size-controlled nanoparticles of magnetite

► From report protocols, chemical synthesis of magnetite with FeCl3 (stable in air) instead of FeCl2 or Fe(NO3)3, precursor. ► Chemical reduction with Na2SO3 provides an additional advantage. ► As any eventual reformation of Fe3+ from reoxidization of produced Fe2+ may be sequestered by remaining SO32− in the medium. ► Nanoparticles are stably individualized with tetramethylammonium hydroxide that acts as a surface-active agent. ► Thermal treatment reduces further the mean sizes of particles, as required for many medical uses.