Inspired by the sticky substance that barnacles use to cling to rocks, MIT engineers have
designed a strong, biocompatible glue that can seal injured tissues and stop bleeding.
The new paste can adhere to surfaces even when they are covered with blood, and can
form a tight seal within about 15 seconds of application.
Such a glue could offer a much more effective way to treat traumatic injuries and to help
control bleeding during surgery.
The research paper appears in the journal Nature Biomedical Engineering.
Finding ways to stop bleeding is a longstanding problem that has not been adequately solved.
Sutures are commonly used to seal wounds, but putting stitches in place is a time-consuming
process that usually isn’t possible for first responders to perform during an emergency
situation.
Among members of the military, blood loss is the leading cause of death following a
traumatic injury, and among the general population, it is the second leading cause of death following
a traumatic injury.
In recent years, some materials that can halt bleeding, also called hemostatic agents, have
become commercially available.
Many of these consist of patches that contain clotting factors, which help blood to clot
on its own.
However, these require several minutes to form a seal and don’t always work on wounds
that are bleeding profusely.
The research team has been working to address this problem for several years.
In 2019, the team developed a double-sided tissue tape and showed that it could be used
to close surgical incisions.
This tape, inspired by the sticky material that spiders use to capture their prey in
wet conditions, includes charged polysaccharides that can absorb water from a surface almost
instantaneously, clearing off a small dry patch that the glue can adhere to.
For their new tissue glue, the researchers once again drew inspiration from the natural
world.
This time, they focused their attention on the barnacle, a small crustacean that attaches
itself to rocks, ship hulls, and even other animals such as whales.
These surfaces are wet and often dirty — conditions that make adhesion difficult.
The researchers’ analysis of barnacle glue revealed that it has a unique composition.
The sticky protein molecules that help barnacles attach to surfaces are suspended in an oil
that repels water and any contaminants found on the surface, allowing the adhesive proteins
to attach firmly to the surface.
The MIT team decided to try to mimic this glue by adapting an adhesive they had previously
developed.
This sticky material consists of a polymer called poly(acrylic acid) embedded with an
organic compound called an NHS ester, which provides adhesion, and chitosan, a sugar that
strengthens the material.
The researchers froze sheets of this material, ground it into microparticles, and then suspended
those particles in medical grade silicone oil.
When the resulting paste is applied to a wet surface such as blood-covered tissue, the
oil repels the blood and other substances that may be present, allowing the adhesive
microparticles to crosslink and form a tight seal over the wound.
Within 15 to 30 seconds of applying the glue, with gentle pressure applied, the glue sets
and bleeding stops, the researchers showed in tests in rats.
One advantage of this new material over the double-sided tape the researchers designed
in 2019 is that the paste can be molded to fit irregular wounds, while tape could be
better suited to sealing surgical incisions or attaching medical devices to tissues.
In tests in pigs, the researchers found that the glue was able to rapidly stop bleeding
in the liver, and it worked much faster and more effectively than the commercially available
hemostatic agents that they compared it to.
It even worked when strong blood thinners were given to the pigs so that the blood did
not form clots spontaneously.
Their studies showed that the seal remains intact for several weeks, giving the tissue
below time to heal itself, and that the glue induced little inflammation, similar to that
produced by currently used hemostatic agents.
The glue is slowly resorbed within the body over months, and it can also be removed earlier
by applying a solution that dissolves it, if surgeons need to go in after the initial
application to repair the wound.
The researchers now plan to test the glue on larger wounds, which they hope will demonstrate
that the glue would be useful to treat traumatic injuries.
They also envision that it could be useful during surgical procedures, which often require
surgeons to spend a great deal of time controlling bleeding.
Another possible application would be to help stop bleeding that occurs in patients who
have plastic tubes inserted into their blood vessels, such as those used for arterial or
central venous catheters or for extracorporeal membrane oxygenation (ECMO).
During ECMO, a machine is used to pump the patient’s blood outside of the body to oxygenate
it.
It is used to treat people with profound heart or lung failure.
Tubes often remain inserted for weeks or months, and bleeding at the sites of insertion can
lead to infection.