Gecko's Stickiness Inspires New Surgical Bandage
TUESDAY Feb. 19, 2008 -- Borrowing a design from the agile, sticky-footed gecko, scientists have created a waterproof, biodegradable adhesive bandage that may one day replace conventional sutures.
The bandage, which could close external wounds and mend internal injuries, has tiny "hills and valleys," similar to those found on the gecko's feet, a Harvard-MIT team reports. This bit of natural engineering allows geckos to cling to almost any surface, even upside-down.
Overlaying the clingy structures is a coating of glue that enables the new bandage to stick onto wet tissues. That ability to stick in wet conditions has been a major challenge to overcome, the researchers said.
"There is a big need for bondable, tape-based adhesives that could be used to seal tissues," said lead researcher Jeffrey M. Karp, director of the Laboratory for Advanced Biomaterials and Stem Cell-Based Therapeutics at the Harvard-MIT Division of Health Sciences and Technology at Brigham and Women's Hospital in Boston.
His team described the new bandage in this week's online edition of the Proceedings of the National Academy of Sciences.
There are other glue-based surgical tapes available, but many are neither flexible nor waterproof, Karp noted. "We decided we needed to create a new material that was elastic, that could conform to the tissue and that could be biodegradable," he said. "So we created this new material that met all of these requirements."
To design a material that could adhere to slippery tissues, the researchers turned to one of nature's stickiest creatures, the gecko. The gecko is able to cling to walls and ceilings using tiny corrugated structures called "nanoscale pillars" on its paws.
"The gecko has no glue, but it uses nanoscale pillars -- a whole carpet of them, millions of them, to adhere to a surface," Karp said. "We decided we could incorporate nanostructures in the surface of our material to enhance the adhesion," he said.
According to the researchers, the new bandage is also biodegradable and dissolves over time, so it wouldn't have to be surgically removed. The amount of time the tape needs to biodegrade can be programmed for specific applications, Karp noted.
Ideally, this type of adhesive bandage should also prevent leaks and deliver drugs for long term, similar to a skin patch, Karp said. He envisions the new adhesive tape being used in hernia surgery, gastric bypass surgery, surgery to remove part of the colon in Crohn's disease and many other invasive procedures. The tape could also be used to seal holes in the bladder or holes caused by ulcers.
"In addition, we believe that these tapes can also be used as a general internal drug-delivery patch to deliver anti-inflammatories, antibiotics or growth factors to encourage healing," Karp said.
The new product could someday replace sutures or staples in some circumstances, such as minimally invasive surgery, Karp said. Because the tape can be folded and unfolded, it could be used in procedures that are difficult to suture because they are performed through a very small incision, he noted.
So far, Karp's team has demonstrated their tape on pig intestine and has implanted the product in the stomachs of rats. When used with pig intestine, the new tape was twice as strong as tape that did not have the nanoscale pillars. In rats, the new tape increased adhesive strength by 100 percent compared with material lacking the nanoscale pillars.
The researchers are now at the point of designing adhesives for specific tissues, because each tissue type is distinct, Karp said. They then hope to start testing the gecko-inspired adhesive in clinical trials.
Posted: February 2008