Nanoparticles Heated by Radio Waves Kill Cells by Destroying Their DNA

A recent publication described the use of graphitic carbon-coated ferromagnetic cobalt nanoparticles to kill cells growing in tissue culture, which is the first step toward adapting the technique to destroy cancer cells in humans.

Investigators at the University of Arkansas (Little Rock, USA) used a catalytic chemical vapor deposition technique to synthesize cubic crystalline graphitic carbon-coated ferromagnetic cobalt nanoparticles (C–Co-NPs) with diameters of around seven nanometers. They used X-ray diffraction and X-ray photoelectron spectroscopy analysis to show that the cobalt nanoparticles inside the carbon shells were preserved in the metallic state. Then, they used fluorescence microscopy images and Raman spectroscopy to demonstrate that the nanoparticles effectively penetrated the cellular plasma membrane of cultured HeLa cells, both inside the cytoplasm and in the nucleus.

Data published in the October 29, 2008, issue of the journal Nanotechnology, revealed that low radio frequency (RF) radiation of 350 kHz induced localized heat into the metallic nanoparticles, which triggered the killing of the HeLa cells, a process that was found to be dependent on the RF application time and nanoparticle concentration. DNA gel electrophoresis assays of the HeLa cells after the RF treatment showed massive DNA fragmentation, which proved that the localized application of heat induced DNA damage and nucleus membrane disintegration.

"We have demonstrated that using a combination of a low frequency, low power radio frequency radiation – which has a high penetration ability in human tissue – with graphitic-magnetic composite nanoparticles could prove an excellent means of raising the temperature at the cellular level above the threshold required for DNA fragmentation or protein denaturation,” said senior author Dr. Alexandru Biris, assistant professor of applied science at the University of Arkansas. "The result is death of the cells. This technique is less invasive and possesses higher efficiency for targeting localized cells. It also has the potential to reduce the side effects associated with traditional cancer therapies.”

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