Last year, the team developed an impressive new alternative to sutures. Their double-sided tape could be used to patch up incisions or wounds in organs, working within a matter of seconds. It could also be used to attach implantable medical devices to tissues.
This was no easy feat. Regular adhesives don’t stick to wet surfaces very well, so the team designed a new type of tape that would. It was made out of a material called polyacrylic acid, embedded with chemical groups called NHS esters. The idea is that the material itself absorbs the excess liquid and forms gentle hydrogen bonds to the tissue. Then the esters help form stronger bond with proteins on the tissue’s surface.
The bandage worked well, but there was one major problem – once it was on, it was really on. And unlike skin, where ripping it off is only briefly painful, doing so on a sensitive organ could cause more serious damage.
For the new study, the researchers set out to develop a way to remove the bandage more safely. To do so they added a disulfide linker molecule, which can not only form strong bonds with tissue proteins but can release those bonds when exposed to certain reducing agents.
The team settled on an agent called glutathione. Not only could this effectively cut the disulfide bonds, but it’s naturally found in many cells in the body, so it’s safe for use. A touch of ordinary baking soda was also mixed in, to sever the hydrogen bonds of the bandage itself.
These were mixed into a saline solution, which could then be sprayed onto the bandage in the body. To test it out, the researchers experimented with different concentrations of each, sprayed onto samples of the bandage applied to pig organs like heart, lungs and intestines.
And it worked. No matter how long the adhesive had been applied, in all cases it was easily removable after being sprayed with the solution. It took about five minutes to work.
“That’s about the time it takes for the solution to diffuse through the tape to the surface where the tape meets the tissue,” says Xiaoyu Chen, first author of the study. “At that point, the solution converts this extremely sticky adhesive to just a layer of slippery gel that you can easily peel off.”
The team also created a version that has tiny channels etched into it, to allow the solution to seep through. This would work for uses like attaching devices to organs, where there wouldn’t be a clear upper surface of the tape to spray it onto. In this case, a surgeon could apply it to the edges of the tape.
Next, the researchers hope to investigate using the new tape to patch up hemorrhages and leaky intestines.
According to newatlas