A smart suture that ties itself into the perfect knot has been developed from a novel polymer with good shape memory. Scientists have developed a material that forms a temporary shape at one temperature, and a permanent shape at a higher temperature, by manipulating the temperature and stress applied to the overall material. The first "smart" degradable suture was created from this new material.

It is now possible to place small devices into the body by threading them through the tiny hollow tubes associated with minimally invasive surgery. The new plastic could first be shaped as a string, and when heated could change into a sheet (to prevent adhesion between two internal tissues after an operation), or a screw to hold bones together, a stent or a suture. To create the new material, scientists designed a biodegradable multiblockcopolymer in which block-building segments are linked together in linear chains. Specifically, the polymer created contains a hard segment and a "switching" segment, both with different thermal properties. One segment melts or makes another kind of transition at a higher temperature than the other.

Much work so far, has focused on "shape-memory" metallic alloys, which are used in applications such as stents for keeping blood vessels open. Shape-memory polymers have also been studied, but none have resulted in medical applications. No shape-memory materials have been biodegradable so far. This new material has the distinct advantage of being bio compatible. To create their new material, scientists from MIT in USA and Aachen in Germany have designed a biodegradable multi block copolymer, in which block-building segments are linked together in linear chains.