Previously, zinc-doped iron oxide nanoparticles (IONPs) were demonstrated to exhibit a two-fold greater magnetic moment compared to their undoped counterparta. The increased magnetic moment could potentially make these IONPs ideal for both MRI and hyperthermia treatment. Here, we report doping of iron oxide with Zn and Co ions via thermal decomposition of corresponding oleates at 340 °C in inert atmosphere followed by oxidation in air at 200 °C in the reaction solution. The reaction products are monodisperse IONPs with diameters of 20-24 nm. The influence of the dopant amount on the IONP structure has been studied. X-ray powder diffraction (XRD) analysis revealed the Zn doped IONPs consist of magnetite-maghemite, similar to that of undoped IONPs. The presence of zinc did not alter the spinel crystal structure. In the case of Co-doping, the XRD pattern contains reflections located in the similar positions as those of the spinel structure. However, a change in the relative intensities indicates the presence of Co oxide along with the spinel structure. X-ray photoelectron spectroscopy (XPS) analysis showed that Zn-containing samples display enrichment of the nanoparticle surface with Zn, while deeper IONP layers are enriched with Fe. This reflects different rates of Zn and Fe oleate decomposition. On the contrary, for Co-doping, this effect is not observed. To estimate the magnetic response, the IONPs synthesized were placed near a neodymium magnet. The Zn-doped samples showed a complete separation from the chloroform (good solvent) solution within forty minutes, while undoped and Co-doped IONPs showed only partial separation within 24 hours. Functionalization of these doped IONPs with PEGylated phospholipids containing different terminal groups allows for the development of universal bioprobes with enhanced MRI and hyperthermia responses.

Development of double action probes based on Zn- and Co-doped iron oxide nanoparticles

254th National Meeting (2017)

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