Carbon-encapsulated magnetic nanoparticles are promising candidate materials for drug-delivery applications. However, due to their hydrophobic and aggregation properties, which indicate lower biocompatibility, proper surface modification of the carbon-based material is required. In the present study, we present the facile route to producing biocompatible magnetic nanocomposite iron oxide/carbon using the liquid medium arc-discharge method. The medium used was ethanol 50% with urea added in various concentrations. Using x-ray diffraction (XRD), the nanocomposite produced was confirmed to have a crystalline structure with distinctive peaks representing iron oxide, graphite, and urea. Fourier transform infrared spectroscopy (FTIR) analysis of the nanocomposite produced in ethanol/acetic acid or ethanol/urea medium shows several vibrations, including Fe–O, C–H, C–O, C=C, C–H, O–H, and C–N, which are intended to be the attached aromatic oxygen- and amine-containing functional groups. The nanocomposite particle was observed to have a core–shell structure that had an iron-compound core coated in a carbon shell possibly modified by polymeric urea groups. The presence of these groups suggested that the nanocomposite would be biocompatible with biological entities in the living body. Lastly, the prepared nanocomposite Fe3O4/C-urea underwent an in-vivo acute toxicity assay to confirm its toxicity. The highest dose of 2000 mg kg−1 BW in this study caused no deaths in the test animals even though cell damages were observed, especially in the liver. This highest dose is considered a maximum tolerable dose and is defined as practically non-toxic.

<p>Synthesis of iron oxide nanoparticles modified with carbon has been successfully performed by submerged arc-discharge method in ethanol/urea medium. Iron oxide used in the fabrication process was prepared by iron electrolysis in an electrolyte solution of NaCl. Fabrication of nanoparticles in this method uses two graphite electrodes. One of them was made in a pointed shape and the other graphite electrodes hollowed out and filled with a mixture of iron oxide, graphite and glue silica (as binder) with a ratio of 1:3:1 (w/w/w). The liquid medium used in this method is a mixture solution of ethanol 50% and urea (0%, 10%, 25% and 50%) with a volume ratio of 1:1 (v/v). The crystalline of iron oxide was characterized using X-Ray Diffraction (XRD), compared to JCPDS No. 89-0597, No. 89-0691 and No. 39-1346. Variations in the urea concentration in the liquid medium provided the changes of the surface character of the synthesized nanoparticles. The changes of surface character were analyzed by the Fourier Transform Infra Red (FTIR) spectra and nanoparticle dispersion in water and ethanol. FTIR spectra showed the absorption of Fe-O, CH, CN, C = O, OH and NH at 460-555 cm^-1, 650-1000 cm^-1, 1000-1350 cm^-1, 1640-1680 cm^-1, 2400-3400 cm^-1, 3200-3400 cm^-1, 3100-3500 cm^-1, respectively. The best hydrophilic surface character achieved when the nanoparticle was synthesized in medium of ethanol 50% with the addition of urea50%. The existence of a functional group attached on the surface of nanoparticles synthesized in ethanol/urea makes these nanoparticles had better dispersion than nanoparticles synthesized in ethanol medium without urea addition.</p>