A team of researchers studied biofouling, or the accumulation of organisms on wet surfaces, to design heavy-duty bio-adhesives for medical devices and advance anti-fouling for the naval industry.
Benthic (bottom-dwelling) marine invertebrates stay close to each other and can stick to just about anything--their adhesive mechanisms are that effective. Barnacles are found clinging to nuclear submarines, naval ships, offshore drilling rigs, jetties and often other animals.
The team, led by Andrew S. Mount, associate professor at Clemson University, specifically analyzed the final stage of larval development of barnacles. During this stage, the larvae, called cyprids, attach to many different surfaces before undergoing full metamorphosis into adult barnacles. This strong adhesion is vital to survival and reproduction of the species.
"In previous research, we were trying to understand how barnacle adhesives were interacting with surfaces of different chemistries," said Mount. "Most biofouling researchers assume that cyprid larval adhesive plaques are primarily composed of proteins and peptides, but we discovered that lipids are also present."
The presence of lipids makes the adhesive material more complex than most researchers previously thought.
Mount and colleagues used a technique Mount developed, called Broadband Coherent Anti-Stokes Raman Scattering, to determine the make up of the adhesive plaque. He found that the material is bi-phasic and synergistic, meaning that it is made up of two phases, a lipid phase and a protein phase, that work together to create powerful adhesion.
Upon further analysis using two-photon microscopy, they found that the lipid phase is a protective measure--it shields the protein phase from the threat of excess hydration and rough seawater. It also keeps the protein phase from thinning out and losing its adhesiveness to the surface.
These findings, published in the journal Nature Communications, represent the first time researchers have analyzed the function of lipids in bio-adhesives.
The study, funded and supported by the Office of Naval Research, will help improve anti-fouling coatings on naval ships. Previous research shows significant increases in the maritime fuel consumption and frictional drag as a result of the sticky marine pests. Furthermore, the bi-phasic nature of the barnacles' adhesive material gives researchers ideas about how to develop better medical and industrial adhesive applications.
