Gecko-Inspired Designs for Bypass Surgeries?

Author:  Maria Huang

Institution:  Duke University
Date:  March 2008

A lizard adaptation to the jungle may soon appear in an altered form in operating rooms. Gecko feet are covered with a complex landscape of ridges that allow them to cling to various materials at the microscopic level. Inspired by this observation in nature, MIT researchers have devised a waterproof adhesive bandage for patching up internal injuries and surgical wounds. MIT Professors Robert Langer and Jeff Karp described their work in the Feb 11 issue of the Proceedings of the National Academy of Sciences.

Although gecko-inspired dry adhesives appeared around 2001, they have not been successfully implemented in medical settings. Adhesives for use in the body must be able to stick in a wet environment, and they must also fulfill strict standards. For example, the materials must be biodegradable, elastic, and non-inflammatory.

Realizing these stipulations, Karp, Langer, and their team created the adhesive out of a "biorubber",a type of flexible, biodegradable polymer previously created by Langer. The scientists molded their "biorubber" material into various hill and valley patterns at nanoscale dimensions, similar to the landscapes observed on gecko feet. The patterns on the "biorubber" base consist of pillars that are less than a micrometer in diameter and three micrometers in height. In order for the bandage to cling tightly to a wet surface (such as heart, lung, bladder tissue), Karp added a thin layer of sugar-based glue on top of the pillars.

To select the stickiest profile, the team tested how well each design patched up pig intestines. Finally, they chose a landscape with pillars spaced just widely enough to grip the tissue beneath. The resulting bandage "is something we never expect to remove," explained Karp, "we're not mimicking the gecko" – which still lift up its sticky feet to walk. Rather, Karp continued, "We are inspired by the gecko to create a patterned interface to enhance the surface area of contact and thus the overall strength of adhesion."

How is this new bandage a significant improvement? Not only can it wrap around and reseal the intestine after a gastric bypass procedure, but it can also patch internal cavities caused by ulcers. Also, because surgeons can fold and refold this adhesive construct, it is especially beneficial in minimally invasive procedures, as tiny incisions are usually difficult to suture. When compared with unpatterned adhesives, the new bandages were twice as strong in patching up pig intestine. Most importantly, the new adhesive barely causes inflammation in rats, and physicians can adjust its elasticity and grip to best suit specific medical applications.

"This is an exciting example of how nanostructures can be controlled, and in so doing, used to create a new family of adhesives," said Langer. In the future, bypass patients may indeed be thanking those surefooted lizards.

Written by Maria Huang

Reviewed by Yash Somnay, Pooja Ghatalia

Published by Pooja Ghatalia.