MIT Institute Professor Robert Langer and faculty member Jeffrey Karp, both affiliated with the Harvard-MIT Division of Health Sciences and Technology, display an adhesive they developed that was inspired by the gecko and may have medical and surgical applications (Credit: MIT/Donna Coveney)

Led by the Harvard-MIT Division of Health Sciences and Technology (HST) faculty members, MIT Institute Professor Robert Langer and Jeffrey Karp, who is a bioengineer, the team utilized the micropatterning technology that is also used to create computer chips. By pouring a biodegradable polymer into microfabricated silicon molds with 200-to-500-nanometer-wide indentations, the researchers have created a "biorubber" tape with nanoscale hills and valleys on its surface, similar to the flexible nanopillars covering geckos' sticky toes. "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." said Karp.

The surface area of this "biorubber" was then coated with a very thin layer of biocompatible sugar-based glue enabling a strong bond even to wet surfaces such as to heart, bladder or lung tissue. When the tape is applied, capillary forces pull tissue into the spaces between the pillars, and the glue adheres to tissue proteins. This biodegradable bandage dissolves over time and does not have to be removed.

Adapting the previously known gecko-like dry adhesive technology for medical applications has been challenging, as a medical adhesive has to be able to stick once and strongly in a wet environment, and to be biocompatible (that does not cause inflammation), biodegradable (that dissolve over time without producing toxins) and elastic (in order to suit the bonded tissues and stretch with them).

MIT's gecko-inspired medical adhesive consists of a "biorubber" base patterned to have pillars that are less than a micrometer in diameter and three micrometers in height. Layered on top is a thin coating of a sugar-based glue. Tests in live rats suggest that the adhesive could be an effective operating room tool for closing surgical wounds. (Credit: MIT/Edwin Chan and David Carter)

The elasticity, degradation rate and pillared landscape of the biorubber are tunable hence the new adhesives can be customized for different medical applications. They can also be infused with drugs designed to be released as the biorubber degrades.

A tape-based medical adhesive may have many applications, as it is noninvasive and easy to place. Unlike sutures and staples traditionally used to close wounds, the new tape doesn't puncture the tissue and could be placed in one motion. The medical tape can also be used during minimally invasive surgeries, which are performed through a very small incision; "It's difficult to tie knots in small places. You could have the tape unfold and apply it through the [laparoscopic] needle." says Karp.

Possible applications of the new surgical adhesive tape also include resealing of the intestine after the removal of a diseased segment or after a gastric bypass procedure, as well as patching a hole caused by an ulcer. Moreover, the tape could release drugs that promote healing, even in tissues that stretch and contract, like the heart. "It's elastic, so it should withstand the mechanical forces of the heart," says Karp. This ability of the bioadhesive patch may be utilized to deliver stem-cell-attracting factor that encourages tissue regeneration into damaged areas of the heart after a heart attack.

Another gecko-inspired synthetic adhesive tape has recently been developed in Berkeley University. Other related issues covered by TFOT include the discovery of a non-toxic, natural glue that has the strongest adhesion force of any known natural material, and the development of a painless microneedles skin patch that can replace conventional injections and enable drug delivery.

The press release regarding the gecko-inspired bioadhesive is available in this MIT news page.