US scientists have created a novel drug delivery system that could massively extend the number of ways in which existing medicines, particularly cancer treatments, are used.

With US government funding, the researchers from University of California, Los Angeles and Northwestern University have employed nanotechnology – engineering on an atomic scale – to develop a system for administering drugs that makes them effectively invisible to the immune system.

Unhindered by the body's immune defenses, the scientists say medicines will stay in the system for longer, allowing more effective treatment. "Using this system, drugs could be released slowly and under control for weeks or longer," said one of the team, Professor Genhong Cheng of UCLA.

The system is based on tiny, inert nano-scale platforms which are lined with the anti-inflammatory drug dexamethasone in addition to the medicine to be delivered. The nano-platforms could also be used to delivery drugs directly to the site of a tumour - making for more effective treatment and fewer side effects

"A drug that is given orally or through the bloodstream travels throughout the system and dissipates from the body much more quickly. Using a more localised and controlled approach could limit side effects, particularly with chemotherapy drugs," said fellow researcher Dr Dan Ho of Northwestern University.

The study, published in this week's issue of the journal ACS Nano, highlights the growing interest in the application of nanotechnology in pharmaceuticals and medicine.

According to the 1995 report The Impact of Nanotechnology in Drug Delivery: Global Developments, Market Analysis and Future Prospects, nanotechnological drug delivery would be of "critical importance to the expected growth of genetic medicine over the next few years". This was due to the promise nanotechnology held for delivering complex, delicate or toxic medicines with great precision.

Also this week it emerged that scientists at the Massachusetts Institute of Technology were developing nanoparticles designed to deliver drugs through mucous membranes, promising better treatments for cystic fibrosis.

Last October there was news that Harvard researchers had developed a nanoparticle that was designed to act as both a drug courier and a delivery reporter by glowing when it delivered its medical cargo inside tumour cells. The technique could allow doctors to see exactly which cells have successfully received a drug, according to a report in New Scientist magazine.

Alison Ross, science information officer at Cancer Research UK, said the use of nanotechnology to target drugs to cancer cells was "an exciting technique". Michael Day