- News Home
5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
- About Us
29 April 2002 (All day)
Surgeons may soon seal hard-to-reach wounds with the aid of novel shape-shifting threads that know how to tie themselves and never need to be removed. The new "smart" biodegradable plastic fiber can knot itself when heated to a few degrees above body temperature. The researchers say the same material could be made to last much longer and one day be used for self-repairing medical devices and shrink otherwise bulky implants--such as screws that hold bones together.
A growing class of materials possess "shape memory"--they hold one form at a certain temperature and transform into another shape when heated. Until now, no such plastics had been used in medical devices, nor had any proved to be biodegradable. The new material, described online 25 April in Science by synthetic chemist Andreas Lendlein of mnemoScience GmbH in Aachen, Germany, and biomedical engineer Robert Langer of the Massachusetts Institute of Technology, is composed of two polymers, each already used separately in clinical applications such as drug delivery.
When combined, the two polymers react to temperature. The higher temperature shape is the plastic's "permanent" form, which it assumes after it's heated. After it cools, the plastic can be stretched or scrunched into temporary forms up to four times larger or smaller than the permanent form. To make the sutures, the researchers took a fiber of their shape-shifting material and, after warming it for a few minutes, cooled it down and stretched it. They used the thread to loosely stitch a wound on a rat. When heated to 40°C, the suture tightened with just the right amount of tension, avoiding damage to the surrounding tissue.
Medical devices that can fit through tiny holes in the body and expand into designed shapes on demand would be invaluable, says laparoscopic surgeon Frederick Finelli at George Washington University Medical Center in Washington, D.C. But he cautions that surgeons might feel uncomfortable not having direct control over shape-changing implants. "If the size is predetermined and you have it in and you heat it up and then it turns out it's too small, what do you do then? These are the things surgeons worry about."