Wounds closed with iCMBA (A) and sutures (S) at different time intervals. Image credit Jian Yang, Penn State University. Click image to enlarge.

Used on both external and internal lacerations, bioadhesives help hold wounds together, promoting healing and preventing infection. However, most adhesives don’t work quite as strongly when in a wet environment – such as surgery on an internal organ. A new study published in Biomaterials may have found the perfect compound to use as glue in wet situations. Modeled after adhesives employed by mussels, the new injectable citrate-based

mussel-inspired bioadhesive (iCMBA) is eight times stronger at keeping wet wounds closed.

Scientists have been looking at mussel compounds as a possible bioadhesive for some time. Mussels have proven their ability to hang on during wet situations, clinging to rocks and boats even under extreme ocean conditions. However, synthesizing the catechol-containing

amino acid L-DOPA identified as the mussel’s super-sticky element was not a simple task. Cost and time were prohibitive to its effectiveness as a mass-produced bioadhesive, says Jian Yang, Associate Professor of Bioengineering at Penn State University.

“Usually, this synthesis is very hard to do. Even after many years of research, making the gel is still difficult,” says Yang. “But we’ve found a very convenient way to make it. It takes just one step, only one reaction.”

In the current study, Yang’s group developed a simple synthesis method for the iCMBA that can cut cost and time.  Under the flow of nitrogen gas, the L-DOPA is added to super-hot (160 degrees °C) citric acid and polyethylene glycol. The resulting polymer is dissolved into water and then freeze dried until it was ready to be added to a sodium periodate solution, which forms an adhesive gel.

When the iCMBA was used on wet wounds in rats, it was found to be 2.5 to 8 times stronger than the clinically used fibrin glue. Also importantly, says Yang, is that it did not elicit significant reactions from the rat’s immune system, which is always a concern when introducing a foreign material to the body. The iCMBA also dissolves when the wound is healed and, because it is made of a natural metabolite, citric acid, and other biocompatible building blocks, is easily absorbed without a threat of long-term toxicity.

“As a glue, it looks promising,” says James Quinn, a professor of medicine and surgery at Stanford University, who is unaffiliated with the study. “But there are a lot of glues out there. I’m not sure if the challenge is finding another adhesive. The challenge is finding an adhesive that can be delivered and work for a specific application where there is a specific need.”

Yang is looking for that specific need. His current target is gastrointestinal surgery, were nicks and cuts to the GI tract could be quickly closed by this glue. He also hopes to investigate its use as a battlefield wound treatment. There could be other applications in the future as well, he says, as our current ability to make such materials creates endless possibilities.

“We are in a designed material age when we can select or make functional building blocks and assemble them together into new materials for a specific application,” he says, filling a need in the biomedical world.

Read the abstract in Biomaterials here.