Biofilms—the slimy scourge of steel ship hulls and copper pipes—may permanently lose their grip on such structures with the aid of a new coating developed by Harvard scientists.
The coating, known by the acronym SLIPS, creates a super-slippery surface that has already shown success in repelling oil and water and in fighting ice and frost buildup.
Joanna Aizenberg and Tak-Sing Wong
|Researchers show off their SLIPS technology against a Teflon-coated surface. They say SLIPS may permanently prevent the formation of biofilms on surfaces ranging from ship hulls to teeth.|
Now, researchers say, the Slippery Liquid-Infused Porous Surface deprives bacterial communities of the footing they need to attach and grow, offering a permanent avenue for prevention.
In a study published in the Proceedings of the National Academy of Sciences (PNAS), lead coauthors Joanna Aizenberg, Alexander Epstein and Tak-Sing Wong coated solid surfaces with the immobilized liquid film to “trick” the bacteria into thinking they had nowhere to attach and grow.
“People have tried all sorts of things to deter biofilm build-up—textured surfaces, chemical coatings, and antibiotics, for example,” said Aizenberg, Amy Smith Berylson Professor of Materials Science at the Harvard School of Engineering and Applied Sciences (SEAS) and a Core Faculty Member at the Wyss Institute for Biologically Inspired Engineering at Harvard.
“In all those cases, the solutions are short-lived at best. The surface treatments wear off, become covered with dirt, or the bacteria even deposit their own coatings on top of the coating intended to prevent them. In the end, bacteria manage to settle and grow on just about any solid surface we can come up with.”
The SLIPS coating, on the other hand, turns “a once-bacteria-friendly surface into a liquid one,” adds Wong, a researcher at SEAS and a Croucher Foundation Postdoctoral Fellow at the Wyss Institute. “As a result, biofilms cannot cling to the material—and even if they do form, they easily ‘slip’ off under mild flow conditions,”
The team believes this is the first successful test of a nontoxic synthetic surface that can almost completely prevent the formation of biofilms over an extended period of time.
|Letters painted from SLIPS coating show its ability to repel biofilms.|
SLIPS is also nontoxic, readily scalable, and self-cleaning, needing only gravity or a gentle flow of liquid to stay unsoiled. Everything seems to slip off SLIPS-treated surfaces, the team says.
The coated surfaces can also combat bacterial growth in environments with extreme pH levels, intense ultraviolet light and high salinity, the researchers say. Not surprisingly, the research has been supported in part by the Department of Defense Office of Naval Research.
Biofilms don’t impede just ships and pipes. They can stick to medical devices and even teeth, causing infections and cavities.
Aizenberg’s team says SLIPS reduced formation of three of the most notorious, disease-causing biofilms — Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus—by 96-99 percent over a seven-day period.
The coating technology works in both a static environment and under flow, or natural conditions, making it ideally suited for coating implanted medical devices that interact with bodily fluids.
‘Very Cool’ Design Tricks
In future studies, the researchers aim to better understand the mechanisms involved in preventing biofilms. They are particularly interested in whether any bacteria transiently attach to the interface and then slip off, if they just float above the surface, or if any individuals can remain loosely attached.
“Biofilms have been amazing at outsmarting us,” said Aizenberg. “And even when we can attack them, we often make the situation worse with toxins or chemicals.
“With some very cool, nature-inspired design tricks, we are excited about the possibility that biofilms may have finally met their match.”