Large scale production of biocompatible magnetite nanocrystals with high saturation magnetization values through green aqueous synthesis

In this work, a straightforward aqueous synthesis for mass production (up to 20 g) of uniform and crystalline magnetite nanoparticles with core sizes between 20 and 30 nm, which are the optimum nanoparticle core sizes for hyperthermia applications, is proposed. Magnetic and heating properties have been analyzed showing very high saturation magnetization and magnetic heating values. To stabilize the naked magnetite nanocrystals at physiological pH and increase their circulation time in blood, they have been covalently coated with carboxymethyl dextran, a biocompatible polymer. The influence of this superficial modification on the magnetic and heating properties has been studied showing that these biocompatible magnetic nanocrystals maintain high saturation magnetization values, good colloidal stability and hyperthermia properties in the presence of the polymeric external layer. These particles, suitably functionalized, could be used to selectively kill cancer cells under a moderate alternating magnetic field (44 mT and 70 kHz).