Effects of biocompatible surfactants on structural and corresponding magnetic properties of iron oxide nanoparticles coated by hydrothermal process

Effect of the biocompatible surfactants; tartaric acid, ascorbic acid and a mixture of them on the properties of the superparamagnetic iron oxide nanoparticles (SPIONs) were investigated, separately. The SPIONs were functionalized via hydrothermal process. It was observed from X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis that the nanoparticles were iron oxide and their shapes were about spherical. And, the particle sizes of all samples were calculated to be less than 8 nm from the TEM images and XRD patterns. Fourier transform infrared spectra and thermogravimetric analysis (TGA) results displayed that all nanoparticles were effectively coated with the surfactants. According to the TGA curves, tartaric acid and ascorbic acid coatings percentages for the corresponding samples are 6.1 and 15.4% at the temperature range of 30–600 °C, respectively. For consequent magnetic analysis, vibrating sample magnetometer showed that all samples were superparamagnetic and saturation magnetizations, M_s were 71.1 and 69.5 emu/g for the nanoparticles coated with tartaric acid and ascorbic acid, respectively. Furthermore, for the first time, the SPIONs were coated with a mixture of tartaric and ascorbic acid. For that, the TGA showed 26.4% mass loss at the same temperature range and the M_s value was found to be 65.2 emu/g with a smaller particle size. In this study, it can be said that considerably high M_s values were obtained. The use of the surfactants during the hydrothermal process provides a good coating of the surface of nanoparticles and the process also increases the M_s with the sizes within superparamagnetic limit and therefore can have the potential to use in biomedical applications.