Surface Modification of Superparamagnetic Iron Oxide Nanoparticles by Argon Plasma for Medical Applications

Hyperthermia is rapidly becoming a clinical reality as a tool for the treatment of malignant disease but there are some major problems in the way of using superparamagnetic nanoparticles coated with polymer in medical applications. Modifying the magnetic nanoparticles without using surface coating is more appropriate. In this study, we presented a new physical technique, by surface treatment of nanoparticles with argon gas plasma, to modify the surface of nanoparticles for improving their crystal structure and magnetization.

In this study, Fe3O4 nanoparticles were synthesized using the co-precipitation method. The nanoparticles were then treated with plasma in a vacuum chamber. In this method, the Radio Frequency (RF) generator 13.56 MHz was used as a power supply and the plasma treatment was applied for 10 and 15 min.

Due to the decrease in surface irregularities, the nanoparticle aggregation decreased and their colloidal stability increased. Moreover, with Value Stream Mapping (VSM) analysis the magnetism of the nanoparticles improved along with an increase of plasma power and plasma treatment time due to the reduced crystal defects and crystal growth. By using the AC magnetic field generator with a frequency of 92 kHz and amplitude of 125 Oe, results show that along with an increase of plasma power and plasma treatment time due to the increased magnetization and colloidal stability, heat generation by these nanoparticles increased in a ferrofluids system in the presence of AC magnetic field. In addition, the locking temperature of nanoparticles has also increased.

Our results suggest that the surface modification of Fe3O4 nanoparticles, using plasma treatment, is an appropriate candidate for some medical applications such as magnetic resonance imaging, drug delivery, and especially for magnetic hyperthermia.