TAGS: UV/EB Cure Adhesives
Researchers from University of Akron have developed a biodegradable and UV cure surgical adhesive for wet surfaces, that works under the body’s range of saltiness and acidity. The adhesive is modelled after adhesive proteins that mussels use to cling to underwater surfaces.
Mimicking Mussels and Sandcastle Worms Adhesive Proteins
Medical glues are challenging to make because they need to attach to tissues dampened with, say, blood or sweat. “
When tissue is soft and wet, it’s very difficult to spread materials on it and stick well,” said study co-author Abraham Joy, chemist at the University of Akron.
Mussels and sandcastle worms cling to underwater surfaces by secreting a mix of oppositely charged adhesive proteins. Electrostatic interaction between the charged proteins creates a coacervate, a suspension of insoluble protein droplets in water. The dense suspension spreads and sticks to surfaces. A weak molecular attraction keeps the proteins in place until cross-links can form among the proteins, as well as between the proteins and the surface, which strengthen and harden the adhesive.
Researchers have tried to mimic this strategy by creating mixes of oppositely charged polymers that can coalesce to form droplets that separate from water. But the adhesives rely on “
very precise conditions of charge, salt, and solution pH. Once the solution conditions change even a little, the [complex] can be lost,” said Jonathan J. Wilker, a chemist at Purdue University.
New Polymer Adhesive Offers Underwater Adhesion
So, the researchers developed a polymer adhesive that does not rely on electrostatic interactions between charged polymers. Instead they start with a polymer with three key parts: a diethanolamide that helps to form a coacervate; a segment containing a catechol, an aromatic diol that plays a key surface-adhesion role in mussel proteins; and a coumarin group that can link to similar groups on other polymer strands via click chemistry when exposed to ultraviolet light.
The team made a solution of the polymer, triggered coacervate formation by warming it, and then filtered out the coacervate, which serves as the glue. To test the glue, they squeezed it onto glass slides submerged in water. After pressing the slides together for 15 min, they shined UV light on the glue for 10 min, cross-linking it to form an elastic adhesive. The adhesive works in solutions with pH 3–12 and 0–1 M salt concentration. The glass slides stuck together with an adhesive strength of 100 kPa, which is comparable to that of mussel adhesive proteins. The charge-neutral system of the adhesive gives impressive underwater adhesion.
The research work represents an important advance in underwater adhesives. The researchers have used the adhesive only on glass. The adhesive is undergoing various tests to confirm its potential in medical situations.
Source: University of Akron