A mussel clings to a clay surface using adhesive proteins found on the secreted byssus threads.

A mussel clings to a clay surface using adhesive proteins found on the secreted byssus threads.

A multidisciplinary team of researchers and faculty at UCSB has made strides in their efforts to develop an underwater adhesive, or glue. By building upon past studies on mussel adhesion, the group has progressed in great bounds and was recently published in Nature Communications.

Kollbe Ahn, a leading author in the Nature publication, worked on the chemistry side of this research. He described the environment at UCSB to be very multidisciplinary to those in Materials Sciences — they “learn from nature and translate the biological understanding to chemistry and engineering.”

Herbert Waite, a UCSB professor of molecular, cellular and developmental biology, described the combination of disciplines that have come together in this research.

“Marine biology revealed how the mussel makes attachment threads and plaques, molecular biology and biochemistry [showed] which proteins are used and when, surface physics and chemical engineering [showed] how the proteins interact with and self-assemble on surfaces and how water is displaced, and so on. In biomimetics, all of these factors need to be consulted,” Waite said.

The research builds upon the work that has already been done in Waite’s lab here at UCSB.

The publication mainly discussed very small-scale uses of underwater adhesives. Saurabh Das, a PhD student in chemical engineering at UCSB, focused on the surface physics side of this project. He worked largely on mussel adhesive-inspired polymers, peptides and single molecular adhesives.

“The Nature Communication publication was more directed toward designing and characterizing small simple molecules of reduced complexities that can be used for nanofabrication applications such as binders for silica particles in lithium ion batteries, solar cells, nano-electronic circuits for adhering metals to dielectric surfaces,” Das said.

And this is just the beginning phase, Das explained.

“There are infinite possibilities of improving the design of the molecules and our work is just a stepping stone to achieve this feat,” Das said.

Much of Waite’s lab’s past research focused on mussels and mussel adhesion. Overall, underwater adhesion is largely based off of the mussel as a model system. Mussel feet contain the amino acid L-dopa, which is found at the end of the mussel byssus threads and on the surfaces they adhere to. Scientists are looking to develop an adhesive for underwater surfaces modeled off of the mussel foot proteins. Waite and Das both explained why the mussel is such a good model system for developing an underwater adhesive.

“Mussel survival in the high energy zone depends on adhesion. Having said that, the mussel is one of many creatures that attach underwater on kelps, barnacles, tubeworms sea anemones, etc. Given that, after 30 years of research we know more about mussel adhesive chemistry than any other, so it’s a natural preference,” Waite said.

“Marine mussels use a bundle of tough, extensible fibers made up of proteins to anchor securely to surfaces under the severe chemical and physical environments of the wave swept shores. They can attach themselves easily in matters of minutes to rocks, metal surfaces of boats, wooden piers and to other mussel shells regardless of the outside environmental conditions,” Das said. “The strength of adhesion between the mussel byssal plaque … and the surface is very strong; they don’t get washed off by the enormous intertidal wave shocks pounding them at 25-50 meters per second.”

Projecting further, Das says that if we can understand the biochemistry and the physics of the proteins the mussel uses to adhere to surfaces, it would enable us to create de novo sealants for injuries and surgeries. There are many other cases in which underwater adhesives would be extremely beneficial, including dental applications, adhesive primers, adhesive for printing electronic circuits, binders for silica particles in lithium ion batteries and solar cells as well as other biomedical uses, and even uses that have not yet been hypothesized.

This has been a groundbreaking collaboration between many disciplines at UCSB. Along with the success of the group and their recent findings and publications, it is a great example of how collaboration can culminate in results much larger than any one group could accomplish on their own.

“Without the collaboration, I cannot imagine this research,” Das said.