Development, evaluation and optimization of superparamagnetite nanoparticles prepared by co-precipitation method

Magnetic nanoparticles (MNPs) are of high interest due to their application in medical fields, in particular for theranostics. Specific properties required for such particles include high magnetization, appropriate size and stability. Biocompatible magnetically soft magnetite particles (Fe 3 O 4 ) have been investigated for biological purposes. The intrinsic instability of these nanoparticles and their susceptibility to the oxidization in air, are limitations for their applications. Various methods have been described for synthesis of these nanoparticles among which co-precipitation method is widely experimented. In order to illustrate the synthesis of MNPs elaborately, the effect of different factors on particle formation were studied. The particles morphology, stability, paramagnetic effect, chemical structure and cytotoxicity were evaluated. Particles of 58 and 60 nm obtained by oleic acid coated (OMNPs) and citric acid coated (CMNPs) magnetite nanoparticles respectively. Transmission electron microscopy images exhibited the real sizes are 15 and 13 nm. Magnetic saturations of these nanoparticles were 72 and 68 emu/g which is suitable for medical applications. Both OMNPs and CMNPs were non-toxic to the SK-Br-3 and MCF-7 cells in the concentrations of <2.5 µg/mL. Since these particles exhibit relatively high magnetic saturation, low dose of such material would be required; therefore, these NPs seem to be suitable for theranostics.