Barnacles might be an annoyance to boaters and even some planners, who find the crustaceans clogging up pipes, but scientists have long been fascinated by their supremely sticky substance.
It has been more than 150 years since the famed biologist Charles Darwin described the cement glands of barnacles and their adhesive properties. Since then, it has been a target to create a synthetic glue that is just as strong underwater and develop surfaces to which barnacles cannot stick, especially as they cause $7.5 billion a year in wasted fuel for the global shipping industry. But scientists had to understand how they do it first.
“The ocean is a complex mixture of dissolved ions, the pH varies significantly across geographical areas and, obviously, it’s wet. Yet despite these hostile conditions, barnacle glue is able to withstand the test of time," Dr. Nick Aldred, a research associate at Newcastle University, said.
While the science regarding just how they manage to stick onto structures in a watery environment has been progressing, more recent research published in the journal Nature described how barnacles secrete lipids and proteins in such a way to "maximize adhesion."
"Lipids, secreted first, possibly displace water from the surface interface creating a conducive environment for introduction of phosphoproteins while simultaneously modulating the spreading of the protein phase and protecting the nascent adhesive plaque from bacterial biodegradation," the study authors wrote.
Aldred said that science about the two-component gluing system has been known for a while now, but what they didn't know was how the glue was able to make adequate contact with the surface already under water.
"We now know that these two substances play very different roles – one clearing water from the surface and the other cementing the barnacle down," Aldred said. "It’s an incredibly clever natural solution to this problem of how to deal with a water barrier on a surface. It will change the way we think about developing bio-inspired adhesives that are safe and already optimised to work in conditions similar to those in the human body, as well as marine paints that stop barnacles from sticking."
Aldred emphasized that how this was done remained a mystery until now because the technology wasn't advanced enough to witness it.
"The key here is the technology. With these new tools we are able to study processes in living tissues, as they happen. We can get compositional and molecular information by other methods, but they don't explain the mechanism. There's no substitute for seeing things with your own eyes," Aldred said. "In the past, the strong lasers used for optically sectioning biological samples have typically killed the samples, but now technology allows us to study life processes exactly as they would happen in nature."
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