Diamond drug delivery

Northwestern University researchers have shown that nanodiamonds are very effective at delivering chemotherapy drugs to cells.

Northwestern University researchers have shown that nanodiamonds – with a similar carbon structure to that of a sparkling 14 karat diamond but on a much smaller scale – are very effective at delivering chemotherapy drugs to cells without the negative effects associated with current drug delivery agents.

Aggregated clusters of the nanodiamonds can carry a chemotherapy drug and shield it from normal cells so as not to kill them, releasing the drug slowly only after it reached its cellular target.

Another advantage of the nanodiamonds, confirmed by a series of genetic studies, is that they do not cause cell inflammation once the drug has been released and only bare diamonds are left. Materials currently used for drug delivery can cause inflammation, a serious complication that can predispose a patient to cancer, block the activity of cancer drugs and even promote tumour growth.

‘There are a lot of materials that can deliver drugs well, but we need to look at what happens after drug delivery,’ said Dean Ho, assistant Prof of biomedical engineering and mechanical engineering at Northwestern’s McCormick School of Engineering and Applied Science.

‘How do cells react to an artificial material left in the body? Nanodiamonds are highly ordered structures, which cells like. If they didn’t, cells would become inflamed. From a patient’s perspective, this is very important. And that’s why clinicians are interested in our work.’

‘Novel drug delivery systems hold great promise in cancer therapeutics,’ added Dr Steven Rosen, director of the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. ‘We anticipate they will allow for more sophisticated means of targeting cancer cells while sparing healthy cells from a drug’s toxicity.’

To make the material effective, Ho and his colleagues manipulated single nanodiamonds, each only two nanometres in diameter, to form aggregated clusters of nanodiamonds, ranging from 50 to 100 nanometres in diameter.

The drug, loaded onto the surface of the individual diamonds, is not active when the nanodiamonds are aggregated; it only becomes active when the cluster reaches its target, breaks apart and slowly releases the drug.

‘The nanodiamond cluster provides a powerful release in a localised place – an effective but less toxic delivery method,’ said Eric Pierstorff, a molecular biologist and post-doctoral fellow in Ho’s research group. Because of the large amount of available surface area, the clusters can carry a large amount of drug, nearly five times the amount carried by conventional materials.

Liposomes and polymersomes, both spherical nanoparticles, are currently used for drug delivery. While effective, they are essentially hollow spheres loaded with an active drug ready to kill any cells, even healthy cells that are encountered as they travel to their target. Liposomes and polymersomes are also very large, about 100 times the size of nanodiamonds which means the nimble nanodiamond clusters can circulate throughout the body and penetrate cell membranes more easily.