Then the cells would expel the nanotubes within 24 hours which would leave them undamaged.
The CNTs can be used to deliver pay-loads such as anti-cancer drugs precisely to tumours then leave its payload without causing stress to healthy cells. Researchers could find no evidence that the nanoparticles caused any damage by their transit in and out of human cells.

Johnjoe McFadden, Professor of Molecular Genetics and lead scientist for the research program, said: “This research shows that CNTs do not accumulate inside living cells so they can be used to deliver drugs or genes without causing any permanent harm. Although much still needs to be done, this is an essential step to developing CNTs as revolutionary therapeutic agents.”

Research has showed that CNTs, functionalised with Ribonucleic acid (RNA), and other payloads, can be ingested by living mammalian cells and then within 24 hours expelled without harming them. These studies point for the first time that nano-vehicles of CNT can be driven in and out of cells precisely, without accumulation and possible toxicological issues, if properly prepared, and applied.  Lead author of the paper, Vera Neves stated: “CNTs are made of carbon, the same material from which our cells are built. So searching for the tiny CNT in the cells is a classic needle in a haystack problem. We use a technique called Raman microscopy, which detects unique vibrations made only by CNTs to track the movement of these nano-vehicles through the healthy cells.’
In separate studies CNT nano-vehicles were functionalised with anti-cancer drug doxorubicin, and CEA antigen to precisely target colon cancer cells.

Professor Ravi Silva, Director of the Advanced Technology Institute at the University, and co-author commented: “Nanotechnology promises to develop revolutionary new treatments for diseases like cancer, diabetes or coronary heart disease. The hope is that customised nanoparticles such as CNT can be injected in the body where they will fix a defective gene or deliver a drug to a sick cell. In this study we show some of the fears associated with nano-toxicology can be mitigated against by carefully controlling the parameters and understanding the key issues in preparing nano-vehicles for theranostic applications.”

The work is part of larger EC-funded project (the CARBIO Marie Curie Research Network) to develop CNTs for biomedical application. This latest work, published in Advanced Functional Materials, shows for the first time that human cells expel nanotubes quite quickly so that by 24 hours, the nanoparticles have all gone.