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Last Updated: Saturday, 10 September 2005, 23:24 GMT 00:24 UK
'Smart' coating to deliver drugs
Image of surgery
The drug-carrying coating could be added to sutures
US scientists have developed a "smart" coating to deliver drugs precisely when and where they are needed in the body.

The special polymer coating slowly dissolves over time, and shows promise for implantable devices such as sutures, screws and pins.

The Massachusetts Institute of Technology team believes such systems could be used to prevent infection following surgery or promote healing.

New Scientist reported on the work from an American Chemical Society meeting.

You might get better control over release times
Dr Martin Garnett, drug delivery researcher at Nottingham University

The Massachusetts team believes it has overcome one of the major stumbling blocks encountered in the past by chemists trying to develop similar drug delivery systems - drugs leaching out before they are meant to.

The approach used by Dr Paula Hammond and her team, along with David Lynn from the University of Wisconsin-Madison, builds on work by Gero Decher, of Louis Pasteur University, in Strasbourg, France, in 1997.

Decher devised a method for depositing thin polymer films on objects of any shape in the hope that drugs embedded in these films would be slowly released as the layers broke down in the body.

Timed release

The problem was that water could penetrate these layers and dislodge the drug early.

Dr Hammond's team say they have prevented this by making the polymer form chains or a mesh that means water cannot enter as readily.

Tests with the drug heparin, a medication that helps prevent blood clots, show that this appears to work, they said.

"We have tuned the polymers to degrade at different rates by changing the composition of the barriers that separate the layers," explained Dr Hammond.

Dr Martin Garnett, drug delivery researcher at the UK's Nottingham University, said: "Finding a way to keep the drugs in the delivery system until you want them to be released is important.

"This work is an evolution rather than a revolution, but it's an interesting development.

"It's doing a similar job to other ideas that are around but doing it in a different way which might be more accessible and easier to use.

"You might get better control over release times," he said.

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