Is this not heartbreaking? My little daughter is dejected because the sole on her favorite pair of boots keeps falling off and the glue we use to put it back on fails as soon as she steps out in the rain. Why? Because water ruins the adhesive.
It’s a problem, and scientists are looking to barnacles for a solution. Not specifically for my daughter’s shoe, but for more serious, notably biomedical purposes. Barnacles are proverbial for their ability to adhere to damp surfaces indefinitely while being immersed in seawater, as researchers at Clemson University know well. From Science Daily:
The team’s findings, published in Nature Communications, examined the last larval stage of barnacles that attaches to a wide variety of surfaces using highly versatile, natural, possibly polymeric material that acts as an underwater heavy-duty adhesive.
"In previous research, we were trying to understand how barnacle adhesives were interacting with surfaces of different chemistries," said Mount, an author on the journal article and founder and director of the Okeanos Research Laboratory in Clemson’s department of biological sciences. "Most biofouling researchers assume that cyprid larval adhesive plaques are primarily composed of proteins and peptides, but we discovered that lipids are also present, which means that the composition of the permanent adhesive is far more complicated than previously realized."
The torpedo-shaped cyprid larvae is the last larval stage before the animal undergoes metamorphosis to become the familiar barnacle seen on pilings and jetties along the coast. Once the cyprid has found a potentially suitable spot, it cements itself permanently in place and then undergoes metamorphosis to become an adult calcareous barnacle.
In order to survive and reproduce, benthic — or bottom-dwelling — marine invertebrates like barnacles need to attach themselves in close proximity to each other. These organisms have evolved an array of adhesion mechanisms that allow them to attach virtually anywhere, including nuclear submarines, maritime ships and offshore drilling rigs, and even to animals like turtles and whales.
It "evolved" by no special design, yet human medical and industrial designers have a devil of a time figuring out how develop a biomimetic equivalent, partly because it’s "far more complicated than previously realized." Not surprisingly, the Office of Naval Research is interested and paid for the research.
[T]he researchers built a two-photon microscopy system and, in collaboration with Marcus Cicerone at the National Institute of Standards and Technology, employed his innovative technique known as Broadband Coherent Anti-Stokes Raman Scattering to delineate the two different phases of the barnacle cyprid adhesive plaque.
"Using these techniques, we found that the permanent adhesive is made up of two phases: a lipid phase and a protein phase," said Mount. "The lipid phase is released first. We believe that this lipid phase protects the protein phase from excess hydration and the damaging effects of seawater, and it may limit the protein phase from spreading too thin and losing its ability to securely adhere the larvae to a surface."
This is the first finding of functional roles of lipids in marine bioadhesives.
The military is also interested in efforts to devise robotic approximations of some familiar quadrupeds. I wrote here a while back about BigDog and Cheetah, funded by DARPA (the Defense Advanced Research Projects Agency) and engineered by Boston Dynamics. Now here’s Spot, also from Boston Dynamics. This "dog" is impressive. It can walk up stairs, and if you kick it, it scrambles gamely and successfully to right itself. It weighs 160 pounds and operates on battery power.
Watch the video. You’ll feel bad for the abused robot.
There’s something touching as well as instructive about science’s struggle to equal nature and her ingenious artifices. Meanwhile many of the same scientists deny the powerful suggestion from biomimetic research itself that these natural artifacts might look designed because they really are.