Monodisperse superparamagnetic nanoparticles by thermolysis of Fe(III) oleate and mandelate complexes

Monodisperse superparamagnetic iron oxide nanoparticles of controlled size were synthesized by thermal decomposition of organic iron compounds in different high-boiling solvents in the presence of oleic acid and/or oleylamine. The compounds included Fe(III) oleate and mandelate, formed from FeCl₃ and the respective acids. The size of the nanoparticles was easily tuned to 8–27 nm by varying the experimental conditions. The nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and magnetization measurements. The hydrophobic coating of the particles was analyzed by thermogravimetric analysis (TGA) and atomic absorption spectroscopy (AAS). To make the particles biocompatible and water dispersible, nontoxic hydrophilic poly(ethylene glycol) derivatives were synthesized and used for phase transfer of hydrophobic particles into water using a ligand-exchange procedure.