Innovative sticky coating mimics mussels: study
CHICAGO (AFP) — US researchers have developed a cheap and simple technique to coat virtually any object, from catheters to contact lenses, by mimicking the adhesive quality of mussels, a study to be released Thursday said.
The investigators say the technology could potentially be used in a range of industrial applications, from adding protective coatings to medical devices and underwater structures, to engineering consumer electronics with flexible, bendable displays.
In laboratory tests, the polymer coating stuck to 25 different substances, from Teflon to cellulose and acrylic, suggesting that this biologically-inspired coating is much more versatile than many of those currently available.
"Existing methods for modifying material surfaces are fairly restricted to specific materials -- what works well on glass would not work well on gold," said Philip Messersmith, professor of biomedical engineering at Northwestern University's McCormick School of Engineering and Applied Science.
"Our method is a much more general strategy for a variety of surfaces. We haven't found a material to which we can't apply it."
Messersmith and his team have been studying the adhesive and binding qualities of mussels and geckos for years in search of biomimetic technologies that could be used for industry.
To create this sticky coating, they took a chemical called dopamine and dissolved it in an open beaker of water. Then they adjusted the water's ph to marine ph, about 8.5, put in an object and several hours later it was coated with a thin film of polydopamine.
The scientists chose dopamine because it mimics the molecular structure of adhesive proteins that give the mussel such sticking power.
In this type of solution, the dopamine undergoes a chemical reaction that results in the formation of a sticky film. The film can be combined with other coatings, depending on the desired application, according to the paper in the journal Science.
"I could put an iPod in the dopamine solution and a thin polydopamine coating would form. Then I could take it out and put it in a metal silver solution and form a coating of copper or silver," said Messersmith.
"This is an astonishingly simple and versatile approach to functional surface modification of materials."
The scientists at Chicago's Northwestern University are already talking to medical device makers about licensing the technology.
Messersmith said the technology could potentially be used to apply antibacterial coatings to medical devices that are placed in the body and are prone to infection, such as cardiac stents or catheters -- even contact lenses.
Stents are metal tubes that are used to prop open blocked arteries. Catheters are commonly used to drain urine from the bladder.
Other applications might include anti-fouling coatings for ships' hulls, oil rigs, and other underwater structures to prevent microorganisms, plants and algae glomming on to them.
The coating could even be incorporated into consumer electronics, because in addition to its adhesive qualities, it can also conduct electricity.
With the appliance's wires embedded in layers of the sticky adhesive, manufacturers could ditch some of the bulky materials they have to use at present, paving the way for flexible devices with bendable displays, Messersmith said.
The film also has an affinity for certain heavy metals, so it could also be used to remove mercury, lead and chromium from bodies of contaminated water, by for example, running the water through some type of column of ball-bearings that have been coated with the polydopamine.
