Improvement of the saturation magnetization of PEG coated superparamagnetic iron oxide nanoparticles

Polyethylene glycol (PEG) coated iron oxide nanoparticles are of interest because of their distinctive properties and potential applications such as magnetic resonance imaging, magnetic hyperthermia and drug delivery. In this study, PEG coated iron oxide nanoparticles were obtained by a two-step synthesis route including coprecipitation and coating. Different amounts of PEG6000 were used for coating and the effect of PEG amount on the structural and magnetic properties of the nanoparticles was investigated. Crystal structure, surface coating and particle size of the nanoparticles were characterized by X-ray diffraction technique, Fourier transform infrared spectroscopy and transmission electron microscopy. The particle size of iron oxide nanoparticles remained almost constant (7–8 nm) with the increase of PEG amount. It was determined from thermogravimetric analysis that the coating percentage of the nanoparticles steadily increased from 2.6 to 6.9 % with the increase of PEG amount from 5 to 15 g. Magnetic properties of the nanoparticles were studied by vibrating sample magnetometer and all samples were found to be superparamagnetic. PEG coated iron oxide nanoparticles showed higher saturation magnetization, Ms values than the uncoated iron oxide nanoparticles. Also, Ms of the coated nanoparticles increased with the increase of PEG coating and reached a value of 62.4 emu/g showing an increase of 19 % over uncoated iron oxide nanoparticles while maintaining the superparamagnetic behavior. This remarkable rise in the Ms of PEG coated iron oxide nanoparticles may improve the control and delivery of the nanoparticles for potential applications.