A team of British researchers has shown that cobalt-chromium nanoparticles can damage the intracellular DNA without ever having to enter the cell itself. These findings may throw a new wrench into the use of nanoparticles in medicine.
From the abstract in Nature Nanotechnology:
Here, we show that cobalt-chromium nanoparticles (29.5 plusminus 6.3 nm in diameter) can damage human fibroblast cells across an intact cellular barrier without having to cross the barrier. The damage is mediated by a novel mechanism involving transmission of purine nucleotides (such as ATP) and intercellular signalling within the barrier through connexin gap junctions or hemichannels and pannexin channels. The outcome, which includes DNA damage without significant cell death, is different from that observed in cells subjected to direct exposure to nanoparticles. Our results suggest the importance of indirect effects when evaluating the safety of nanoparticles. The potential damage to tissues located behind cellular barriers needs to be considered when using nanoparticles for targeting diseased states.