Anyone who’s had a bandage slip off in the shower knows that most sticky stuff just doesn’t work when it’s wet. Thinking about ways to keep adhesives strong in slick situations is an issue that comes up in a lot of industries, from cosmetics to construction. But long-lasting stickiness is especially important when it comes to closing wounds during surgery on internal organs.
Keeping the medical field in mind, researchers from MIT took a cue from a perhaps unlikely source: spiders, whose webs can trap insects even on dewy mornings. With webs as their guide, the team developed a new type of tape that works in environments with high levels of moisture, according to a new study published in the journal Nature.
The BBC reports that researchers noticed that spiderwebs contain charged polysaccharides that almost instantly absorb moisture from the insects that crawl into their trap, producing a dry patch to adhere to.
To mimick the spiderwebs, the team designed a material that wicks away the moisture from tissues before rapidly creating a bond. To absorb water, they chose polyacrylic acid, an absorbent material used in disposable diapers. The acid sucks up the water and creates weak hydrogen bonds, which briefly holds the materials together.
Then a class of chemicals called N-Hydroxysuccinimide (NHS) esters embedded in the polyacrylic acid take over, forming stronger covalent bonds with proteins in the tissue in only five seconds. Depending on the application the bandage is being used for, it can be reinforced with gelatin, which breaks down in the body in days or weeks, or chitosan, a polysaccharide found in insect shells that last from a month to a year.
“There are over 230 million major surgeries all around the world per year, and many of them require sutures to close the wound, which can actually cause stress on the tissues and can cause infections, pain, and scars,” study author Xuanhe Zhao, a mechanical engineer at MIT, says in a statement. "We are proposing a fundamentally different approach to sealing tissue."
The team has yet to test the new material on humans, but in experiments on pigs, they successfully used it to repair skin, small intestine, stomach and liver tissue.
“It’s very challenging to suture soft or fragile tissues such as the lung and trachea, but with our double-sided tape, within five seconds we can easily seal them,” says first author Hyunwoo Yuk, a materials scientist at MIT, in a statement.
The team is also looking at other applications for the tape, like implanting medical devices onto organs like the heart.
“I anticipate tremendous translational potential of this elegant approach into various clinical practices, as well as basic engineering applications, in particular in situations where surgical operations, such as suturing, are not straightforward,” Yu Shrike Zhang of Harvard Medical School, not involved in the study, says in a statement.
This is not the only medical advance based on spiderwebs. In 2017, researchers at the University of Cambridge developed an artificial spider silk that is 98 percent water. While the material has lots of potential applications, like producing protective gear, parachutes and even airplane bodies, it could also be used in surgery. Not only are the molecules biocompatible, meaning the body is less likely to reject them or cause an inflammatory reaction, the silk proteins could allow doctors to coat the fibers with antibiotics or other medicines, reducing the possibility of infection.