Cobalt nanoparticles coated with graphitic shells as localized radio frequency absorbers for cancer therapy

Abstract

Graphitic carbon-coated ferromagnetic cobalt nanoparticles (C-Co-NPs) with diameters of around 7 nm and cubic crystalline structures were synthesized by catalytic chemical vapor deposition. X-ray diffraction and x-ray photoelectron spectroscopy analysis indicated that the cobalt nanoparticles inside the carbon shells were preserved in the metallic state. Fluorescence microscopy images and Raman spectroscopy revealed effective penetrations of the C-Co-NPs through the cellular plasma membrane of the cultured HeLa cells, both inside the cytoplasm and in the nucleus. Low radio frequency (RF) radiation of 350 kHz induced localized heat into the metallic nanoparticles, which triggered the killing of the cells, a process that was found to be dependent on the RF application time and nanoparticle concentration. When compared to carbon nanostructures such as single-wall carbon nanotubes, these coated magnetic cobalt nanoparticles demonstrated higher specificity for RF absorption and heating. DNA gel electrophoresis assays of the HeLa cells after the RF treatment showed a strong broadening of the DNA fragmentation spectrum, which further proved the intense localized thermally induced damages such as DNA and nucleus membrane disintegration, under RF exposure in the presence of C-Co-NPs. The data presented in this report indicate a great potential of this new process for in vivo tumor thermal ablation, bacteria killing, and various other biomedical applications.

Magnetic nanoparticles for cancer therapy

“…Xu et al studied hyperthermia with the assistance of cobalt nanoparticles, although they did not apply an alternating magnetic field. This research group heated the particles by ultrasonic sound (350 kHz) and showed that the effects of the nanoparticles in vitro depended on the exposure time and the nanoparticle concentration [75] . However, as Rodriguez-Luccioni et al demonstrated in a comparative study, the viability of cells in vitro was affected significantly more by magnetic hyperthermia than by heating in a water bath, which implicates that magnetic hyperthermia might have additional effects on tumor cell viability [76] .…”

Application of alternative energy forms in catalytic reactor engineering

“…Metal oxide [17, 66 -70] , metallic, mainly Fe and Co [71 -73] , and bimetallic, such as FePt [74,75] MNPs have been proposed for this purpose. Many of these materials were coated, to provide an inert and biologically compatible outer shell made of silica [67] , gold [43,57,76] or carbon [71,73] . [36,48] .…”

Formation of core/shell structured cobalt/carbon nanoparticles by pulsed laser ablation in toluene

“…Intriguing potential applications of carbon-coated magnetic nanoparticle systems are emerging, such as the magnetic memory devices, drug delivery, and tumor therapy. [17][18][19] In this paper, we report the results on the preparation of cobalt nanoparticles using PLAL technique at room temperature, with the metal cobalt target immersed in toluene. Without the addition of surfactants, cobalt nanoparticles with graphitic carbon coating were produced.…”