Gecko's Feet Inspire an Adhesive Bandage for Surgery

Nanotechnology copies nature, as a polymer bandage inspired by the feet of an agile lizard offers a way of repairing tears in organs and other tissues from surgery or injury.

Researchers at Harvard-MIT (Boston, MA, USA) molded the novel bandage based on a pattern on the bottom of the lizard's feet, which is formed by millions of hair-like structures on each foot pad called setae; the bandage has similar tiny pillars, each 100 times finer than a human hair. The bandage has an additional sugar-based adhesive to keep it firmly in place. The bandage has a wide range of applications, from wrapping around and resealing the intestine after removal of a diseased segment, to sealing a hole in the bladder, or healing diabetic skin ulcers. The bandage can be folded and unfolded, making it ideal for minimally invasive laparoscopic surgery, since suturing in the limited space available can be particularly challenging for even the most skilled of surgeons. The bandage could also be imbued with slow-releasing anti-inflammatory or antibiotic drugs to aid healing.

The researchers tested their gecko-inspired bandage in a hernia-like repair in laboratory rats and found the adhesive tape had twice the strength as a similar material, without the glue. The rats had only a mild inflammatory response to the adhesive, making it within acceptable limits for use in humans. The study was published in the February 18, 2008, online issue of the Proceedings of the National Academy of Sciences (PNAS).

"I think we've demonstrated a proof of principle that we can take concepts from nature and apply them to real human problems,” said co-developer Dr. Jeff Karp, Ph.D., of the division of health sciences and technology. "There is a great need for an easy-to-use adhesive tape that could either replace sutures and staples in some cases, or augment them in others.”

Geckos are small to average sized lizards belonging to the family Gekkonidae which are found in warm climates throughout the world. The toes of the gecko have attracted a lot of attention, as they adhere to a wide variety of surfaces without the use of liquids or surface tension. Recent studies of the spatula tipped setae on gecko footpads demonstrate that the attractive forces that hold geckos to surfaces are van der Waals interactions between the finely divided setae (almost 500,000 setae on each foot, and each of these tipped with between 100 and 1,000 spatulae) and the surfaces themselves. The length of each seta is twice the diameter of a human hair, and each spatulae is 200 billionth of meter long, just below the wavelength of visible light.


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