Synthesis of novel CoC_x@C nanoparticles

摘要

CoC_x nanoparticles encapsulated in carbon shells were synthesized using a pulsed plasma in liquid ethanol. This is the first time that monolithic cubic phase cobalt carbide nanoparticles have been obtained. X-ray diffraction refinement of the nanoparticles showed that the lattice parameter of prepared cubic phase cobalt carbide is larger than that of CoC_x (44-0962) and cubic phase Co (15-0806 and 01-1259). The x-ray absorption fine structure spectra near the Co K-edge of the synthesized sample indicated differences from commercial metallic cobalt and cobalt oxide samples. High resolution transmission electron microscopy revealed that a thin carbon coating covered the surface of the nanoparticles. These carbon layers might isolate core CoC_x material from the outside environment, and allow functionalization by carboxyl groups for the further purpose of targeted drug delivery. The obtained CoC_x@C particles, with a crystallite size of about 10 nm confirmed by the electron microscope, aggregate into 20-40 nm secondary particles in distilled water as shown by dynamic light scattering, and possess high saturation magnetization of about 120 emu g~(-1). The sodium 3′-[1-(phenylaminocarbonyl)-3,4-tetrazolium]-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate assay and defragmentation of deoxyribonucleic acid on MCF-7 cells after incubation with particles indicate relatively low cytotoxicity of CoC_x@C nanoparticles, compared with micro-sized and nano-sized metallic cobalt particles and commonly used iron oxides. For the small sized CoC_x@C particles, the release of cobalt ions was checked by a chelation method with ethylenediaminetetraacetic acid solution to be at a very low level compared with other reference materials.