Stable Colloidal Suspension of Magnetic Nanoparticles for Applications in Life Sciences

Various utilizations of magnetitc nanoparticles (MNPs), highly biocompatible, in biomedicine and environmental sciences require not only fine granulated powder but also stable dispersion in fluid media. MNPs were synthesized by chemical co-precipitation route. MNP surface modification was carried out with oleate ions as coating shell able to ensure colloidal MNP stability and also allowing further adding of secondary organic shell for conferring hydrophylicity or possibility of grafting various biomolecules. Granularity of colloidal MNPs was analyzed using microscopy techniques, crystalline properties by X-ray diffraction while superparamagnetic properties by magnetometry were assessed. The influences of magnetic and non-magnetic stirring, used alternatively during the preparation steps - on the microstructural and magnetic features are discussed. The MNP suspensions response to electromagnetic fields was studied by measuring the components of magnetic susceptibility. The investigation results suggested the usefulness of the yielding technology based on non-magnetic mixing during both ferrophase preparation and surface modification.