TOKYO, July 8, 2009 (AFP) - Japanese scientists said Wednesday they had developed a surgical 'nano-sheet' one thousand times thinner than Cellophane that can patch up internal wounds and later dissolves inside the body.

Japan's Waseda University researcher Toshinori Fujie displays the ultra thin flexible surgical sheet, made of chitosan from crab shell and sodium alginate from kelp at his laboratory in Tokyo - Photo: AFP/Yoshikazu Tsuno

The transparent and adhesive sheeting, made from a substance derived from crab shells and a viscous gum from algae, is just 75 nanometres thick. A nanometre is one-billionth of one metre.

"This is the world's thinnest adhesive plaster," said Toshinori Fujie, a researcher involved in the joint project by Tokyo's private Waseda University and the National Defense Medical College.

"We know food Cellophane clings on to the surface of various objects. We have made a sheet ultimately thin... so that it is highly flexible and can stick to organs well with no glue," he told AFP.

Surgeons normally stitch or staple wounds, or they use sheets several millimetres thick coated with fibrin, a protein that makes blood clot and works like glue but which can cause unwanted sticking to nearby tissue.

In an experiment repeated several times, the team placed a square piece of the new nano-sheet onto a six-millimetre-wide hole in a dog's lung.

The sheet was strong enough to withstand the pressure of the dog's breathing and helped the wounds heal within one month, leaving no visible trace, Fujie said.

Researchers hope to launch human clinical trials in three years.

They may also expand the use of the sheets for external use.

"Organs repaired with this sheet do not have scars, unlike after stitches," Fujie said. "We believe this could also be true on the skin."

This would open the way for other applications, for example for surgery wounds in breast cancer patients, he said.

"Some people also want to use this for treating bed sores. The next application will definitely be on the skin," he said.

Fujie said the inventors were also thinking of other possibilities -- including in cosmetic use, for example by stretching out wrinkles or holding in place skin conditioners.

"As this is transparent on the skin, you could be wearing a face pack while working in the office," he said.