Underwater mussel glue inspires synthetic cement

Those who have tried to extract a mussel from anything from wood to rock know how stubborn underwater molluscs are – and their slimy secret has long captivated scientists. For years, researchers have tried to replicate the extraordinary adhesive and its properties in the lab, targeting some of the eight proteins that mussels secrete and use to coat an organ called a foot that mussels use to attach themselves to surfaces.

Now, using a new method to organize molecules, researchers at Northwestern University have created a material that works even better than the glue they were trying to imitate. Their findingspublished in the Journal of the American Chemical Societyexplain how these protein-like polymers can be used as a platform to create new materials and therapeutics.

“The polymer could be used as an adhesive in a biomedical context, which now means you can stick it to a specific tissue in the body,” said Nathan Gianneschi of Northwestern. “And keep other molecules nearby in the same place, which would be helpful for wound healing or wound repair.”

Gianneschi led the study and is the Jacob and Rosaline Cohn Professor of Chemistry at Northwestern’s Weinberg College of Arts and Sciences.

Proteins like those secreted by mussel feet exist in nature. Evolution has made a habit of creating these long, linear chains of amino acids that repeat over and over again (called tandem repeating proteins, or TRPs). Sometimes appearing stretchy, solid, and sticky, protein frameworks appear in the wings and legs of insects, spider silk, and the legs of mussels. Scientists know the exact primary amino acid sequences that make up many of these proteins, but struggle to replicate the complicated natural process while retaining the extraordinary qualities.

The paper’s first author, Or Berger, a postdoctoral researcher in Gianneschi’s lab who studies peptides — those very chains of amino acids — had an idea for how to organize amino acid building blocks differently. to reproduce the properties rather than directly copying the structure of mussel proteins. .

By taking the building block of one of the proteins (the repeating decapeptide, a 10 amino acid sequence that makes up the mussel foot protein) and plugging it into a synthetic polymer, Berger thought the properties could be improved. .

As associate director of the International Institute of Nanotechnology, Gianneschi has built much of his lab around the idea of ​​mimicking proteins in function using polymer chemistry. In precision therapeutics, drug therapies such as antibodies and other small molecules combat certain diseases, where a nanocarrier is used to more efficiently deliver a drug to a target. But Gianneschi says protein replication could approach biological problems differently, altering the interactions within and between cells involved in disease progression, or between cells, tissues and materials.

“Proteins organize amino acids into chains, but instead we took them and arranged them in parallel, on a dense synthetic polymer backbone,” Gianneschi said. “It’s the same thing we started doing to control specific biological interactions, so the same platform technology that we’ll use for future therapies has really become potentially interesting in materials science.”

The result was something that looked like a brush of peptides rather than a loop of amino acids in a straight line like a chain. While the new process may appear to add an extra step, the formation of protein-like polymers (PLPs) skips several steps, requiring researchers to form peptides in a readily available synthesizer and insert them into the compact backbone rather than go through tedious stages of protein. expression.

To test the effectiveness of the new material, the researchers applied either the polymeric material or the native mussel protein to glass plates. The researchers placed cells on the plates and then, after washing them, assessed the number of cells present, attached or not, to assess the performance of the materials. They found that the PLP formed a cellular superglue, leaving the most cells attached compared to the native mix and the untreated plate.

“We actually didn’t want to improve the properties of the mold,” Berger said. “We just wanted to mimic it, but when we went to test it in several different tests, we actually got better properties than the native material in those parameters.”

The team hopes the model can be broadly applicable to other proteins that repeat their sequence to win based on a new way of replicating proteins. They hypothesize that such a platform could perform better than its native counterparts because it is denser and scalable. Gianneschi said this is the first of many papers to discuss polymer-based protein mimics, and he’s already thinking about applications for future materials.

Resilin, for example, a stretchy protein found in the legs and wings of insects, could be used to make flexible drones and other robots.

“When you talk about polymers, some people immediately think of plastic bags and bottles,” Gianneschi said. “Instead, it’s highly functional and advanced precision materials made accessible.”

Gianneschi and Berger are the pending intellectual property inventors in this space. Gianneschi is also a professor of biomedical engineering and materials science and engineering at the McCormick School of Engineering and a member of the Chemistry of Life Processes Institute, the Simpson Querrey Institute, and the Robert H. Lurie Comprehensive Cancer Center at Northwestern University. He is the co-founder of a company, Grove Biopharma, which seeks to develop versions of these materials as translational therapies.

– This press release was originally posted on the Northwestern University website

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