A new waterproof glue, modeled after the proteins that help mussels, barnacles and other shellfish cling to objects, may have important medical and naval applications.
The strong adhesive could be useful in repairing ships or healing wounds, according to a new study conducted by researchers at the Massachusetts Institute of Technology.
In order to create their new adhesives, the researchers engineered bacteria to produce a hybrid material that uses naturally sticky mussel proteins and a bacterial protein found in biofilms. When combined, these proteins create even stronger underwater adhesives than those secreted by mussels, according to an MIT press release.
The project was outlined in the Sept. 21 issue of the journal Nature Nanotechnology. It represents a new type of approach that can be exploited to synthesize biological materials with multiple components.
"The ultimate goal for us is to set up a platform where we can start building materials that combine multiple different functional domains together and to see if that gives us better materials performance," says Timothy Lu, an associate professor of biological engineering and electrical engineering and computer science (EECS) and the senior author of the paper, according to the release.
The paper's lead author is Chao Zhong, a former MIT postdoc who is now at ShanghaiTech University. Other authors include graduate student Thomas Gurry, graduate student Allen Cheng, senior Jordan Downey, postdoc Zhengtao Deng, and Collin Stultz, a professor in EECS.
Lu and his colleagues say the process used to create the adhesive is extensive. Previously, scientists engineered E. coli bacteria to produce individual mussel foot proteins. These materials don't capture the complexity of the natural adhesives though.
For the new study, the MIT team wanted to engineer bacteria to create two different foot proteins, combined with bacterial proteins called curli fibers, fibrous proteins that can clump together and assemble themselves into larger and more complex meshes, according to the release.
Lu's team was able to engineer bacteria so they would produce proteins consisting of curli fibers bonded to either mussel foot protein 3 or mussel foot protein 5. Once they purified these proteins from the bacteria, the researchers let them incubate and form dense, fibrous meshes.
This created a material with a regular yet flexible structure that binds strongly to both dry and wet surfaces.
"The result is a powerful wet adhesive with independently functioning adsorptive and cohesive moieties," says Herbert Waite, a professor of chemistry and biochemistry at the University of California at Santa Barbara who was not part of the research team, according to the release. "The work is very creative, rigorous, and thorough."
The researchers can only produce small amounts of the adhesives using this process, so they are now trying to improve the process and create larger quantities. They are also planning on experimenting with adding some of the other mussel foot proteins.
"We're trying to figure out if by adding other mussel foot proteins, we can increase the adhesive strength even more and improve the material's robustness," Lu says.
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