Water dispersible iron oxide nanoparticles coated with covalently linked chitosan

Magnetic nanoparticles consisting of iron oxide cores modified with covalently linked chitosan oligosaccharide (CSO) that are colloidally stable in water and buffers were obtained. Primary oleic acid coated nanoparticles were synthesized through the thermal decomposition method and the surface ligand exchanged to a carboxylic acid silane. Amide linkage between the chitosan and magnetic nanoparticles was obtained through carbodiimide activation, under conditions which promoted particle stability and chitosan solubility. Magnetic measurements indicate that the particles are superparamagnetic. Measurements of hydrodynamic diameter and zeta potential, coupled with TEM measurements, indicated that CSO coated nanoparticles consist of single primary particles coated with a chitosan corona. These nanoparticles are stable in water for a wide range of pH, and in commonly used biological buffers, such as phosphate buffered saline (PBS), Hank's balanced salt solution (HBSS), and Dulbecco's modified eagle's medium (DMEM) with fetal bovine serum (FBS).