Abstract
In this study, magnetite (Fe~3~O~4~) nanoparticles with a size range of 8โ20 nm were prepared by the modified controlled chemical coprecipitation method from the solution of ferrous/ferric mixed saltโsolution in alkaline medium. In the process, two kinds of surfactant (sodium oleate and polyethylene glycol) were studied; then, sodium oleate was chosen as the apt surfactant to attain ultrafine, nearly spherical and wellโdispersed (waterโbase) Fe~3~O~4~ nanoparticles, which had well magnetic properties. The size and size distribution of nanoparticles were determined by particle size analyzer. And the magnetite nanoparticles was characterized by Xโray powder diffraction (XRD) analysis, transmission electron microscopy (TEM), electron diffraction (ED) photography, Fourier transform infrared spectrometer (FTโIR), and vibratingโsample magnetometer (VSM). Also the effect of many parameters on the Fe~3~O~4~ nanoparticles was studied, such as reaction temperature, pH of the solution, stirring rate and concentration of sodium oleate. And the 5โdimethylthiazolโ2โylโ2,5โ diphenyltetrazolium bromide (MTT) assay was performed to evaluate the biocompatibility of magnetite nanoparticles. The results showed that the Fe~3~O~4~ nanoparticles coated by sodium oleate had a better biocompatibility, better magnetic properties, easier washing, lower cost, and better dispersion than the magnetite nanoparticles coated by PEG. ยฉ 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007