Physical and in vitro evaluation of ultra-fine cohenite particles for the prospective magnetic hyperthermia application

We report here the structural and biocompatibility studies of bare nanoparticles of theta-Fe3C and its ferrofluid, prepared using pluronic acid F127 as a stabilizer. For both the cases, this carbide was compatible (~ 80% cell viability after 48 h) with A549 human lung carcinoma cells up to a concentration of 2 mg/mL which was comparable to that of its magnetic iron oxide counterparts. The X-ray diffraction and transmission electron microscopy validated its orthorhombic phase having an average particle size of ~ 6 nm. The surface property of the theta-Fe3C sample was analyzed by X-ray photoelectron spectroscopy (XPS), which designates the existence of only Fe and C. The Mossbauer spectroscopy for the sample also verified this carbide phase. The room temperature saturation magnetization for the sample at 2 T was around 78.2 Am-2/kg. This value was more than that of magnetic iron oxide nanoparticles of similar size. Its ferrofluid displayed substantial temperature rise with time during the magnetic hyperthermia experiment. Consequently, the obtained specific loss power, as well as intrinsic loss power values, were 46 W/g and 0.526 nHm(2)/kg, respectively, at a field of 23 mT and 261 kHz. Both the values indicated its suitability for magnetic hyperthermia application.