New coating prevents more than 99 percent of harmful bacterial slime from forming on surfaces

Jul 30, 2012
This shows the SLIPS technology for preventing biofilm formation as compared to a Teflon coated surface. Credit: Joanna Aizenberg and Tak-Sing Wong

Biofilms may no longer have any solid ground upon which to stand.

A team of Harvard scientists has developed a slick way to prevent the troublesome from ever forming on a surface. Biofilms stick to just about everything, from copper pipes to steel to glass . The slimy coatings are more than just a nuisance, resulting in decreased , contamination of water and , and—especially in medical settings—persistent infections. Even cavities in teeth are the unwelcome result of bacterial colonies.

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 an 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," says 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."

Taking a completely different approach, the researchers used their recently developed technology, dubbed SLIPS (Slippery-Liquid-Infused Porous Surfaces) to effectively create a hybrid surface that is smooth and slippery due to the liquid layer that is immobilized on it.

The word "SLIPS" is coated with the SLIPS technology to show its ability to repel liquids and solids and even prevent ice or frost from forming. The slippery discovery has now been shown to prevent more than 99 percent of harmful bacterial slime from forming on surfaces. Credit: Joanna Aizenberg, Rebecca Belisle, and Tak-Sing Wong

First described in the September 22, 2011, issue of the journal Nature, the super-slippery surfaces have been shown to repel both water- and oil-based liquids and even prevent ice or frost from forming.

"By creating a liquid-infused structured surface, we deprive bacteria of the static interface they need to get a grip and grow together into biofilms," says Epstein, a recent Ph.D. graduate who worked in Aizenberg's lab at the time of the study.

"In essence, we turned a once bacteria-friendly solid surface into a liquid one. As a result, biofilms cannot cling to the material, and even if they do form, they easily 'slip' off under mild flow conditions," adds Wong, a researcher at SEAS and a Croucher Foundation Postdoctoral Fellow at the Wyss Institute.

Aizenberg and her collaborators reported that SLIPS reduced by 96% the formation of three of the most notorious, disease-causing biofilms—Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus—over a 7-day period.

By tricking bacteria into thinking they have nowhere to attach and grow, researchers have developed a remarkable way to deter harmful biofilm growth on surfaces. Credit: Joanna Aizenberg, Rebecca Belisle and Tak-Sing Wong

The technology works in both a static environment and under flow, or natural conditions, making it ideally suited for implanted medical devices that interact with bodily fluids. The coated surfaces can also combat bacterial growth in environments with extreme pH levels, intense ultraviolet light, and high salinity.

SLIPS is also nontoxic, readily scalable, and—most importantly—self-cleaning, needing nothing more than gravity or a gentle flow of liquid to stay unsoiled. As previously demonstrated with a wide variety of liquids and solids, including blood, oil, and ice, everything seems to slip off surfaces treated with the technology.

To date, this may be the first successful test of a nontoxic synthetic surface that can almost completely prevent the formation of biofilms over an extended period of time. The approach may find application in medical, industrial, and consumer products and settings.

In future studies, the researchers aim to better understand the mechanisms involved in preventing biofilms. In particular, they are 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. 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," concludes Aizenberg.

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User comments : 26

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Sonhouse
3.7 / 5 (3) Jul 30, 2012
So what is the 1% of bacteria that CAN stick to this stuff? Also, is it compatible with real teeth?
extremity
3 / 5 (6) Jul 30, 2012
This seems to be a really neat application. With a lot of potential in multiple fields. My only two questions are:

1) Is it non-toxic?

2) Will it find a real world application before it is bought up by a big name company and locked away in a safe never to be seen or used again.

@Sonhouse: The author of the articles makes a vague reference to dental applications, but from what I can see, the actual research does not talk about it being tested in that surface. Although, it would be an interesting to see if it could keep plaque off teeth, it would most likely also prevent surface restoration of enamel.
zz6549
3 / 5 (1) Jul 30, 2012
@extremity

You have it backwards. If it ISN'T bought up by a company (big-name or small-name, doesn't really matter), then it will most certainly end up collecting dust in the Harvard basement.

But even if it is commercialized, there's no guarantee that it will ever make it to market. It may be infeasible to produce in any significant quantity, or the real-world performance will be disappointing.
Telekinetic
2.5 / 5 (15) Jul 30, 2012
As a product where sterility is critical like an operating room, it has a future. I think, though, there is always a danger to curtailing our exposure to bacteria. It makes our immune system more vulnerable to strains of potentially deadly bacteria.
cdt
not rated yet Jul 31, 2012
As a product where sterility is critical like an operating room, it has a future. I think, though, there is always a danger to curtailing our exposure to bacteria. It makes our immune system more vulnerable to strains of potentially deadly bacteria.


Agreed, though I do think there are a lot of places this could be useful. Breweries, for one. Milk processing plants and dairy farms for another. Indeed, in just about any place where they prepare food and require near sterile conditions.
alfie_null
5 / 5 (2) Jul 31, 2012
I wonder if this technology would also have some application in situations where lubrication is needed?
BradynStanaway
5 / 5 (1) Jul 31, 2012
I want to know the temperature ranges it can work in..
Satene
2.7 / 5 (7) Jul 31, 2012
The SLIPS are important with their self-healing ability. They were promoted originally as a self-lubricating surfaces, but their usability scope is apparently wider. Maybe the pitcher plants are using their antibacterial activity too, because they cannot digest its prey fast and the bacteria form a natural competition for them.
antialias_physorg
3.3 / 5 (7) Jul 31, 2012
So what is the 1% of bacteria that CAN stick to this stuff?

I'm reading this as 100% of all bacterial strains, but just 1% by volume of what would ordinarily grow on a surface.

1) Is it non-toxic?

From the article:
SLIPS is also nontoxic


SatanLover
3.4 / 5 (5) Jul 31, 2012
inhale this. hello lung cancer.

when will we start learning that bacteria are GOOD?
if you let the good bacteria alone they will overwhelm the bad bacteria and nothing bad will happen.
bearly
1 / 5 (2) Jul 31, 2012
I want to be able to go to Wal Mart or where ever and buy a bottle of this stuff to spray onto my car windshield or tent or whatever I get the urge to use it on. But ONLY if it is safe and non toxic.
Mike_Massen
2.3 / 5 (12) Jul 31, 2012
@cdt and others:-

So people have forgotten Brass is a great oligodynamic material and instead go down the route of preventing formaion of (larger colonies) and issues of stickiness... Brass kills, Stainless steel door knobs in hospitals however harbour and protect bacteria. But ordinary people dont know this and like the look of stainless, education is so important, bring back brass and simultaneously increase bio-availability of zinc and copper - the two most deficient minerals in the average western diet !
Vendicar_Decarian
2 / 5 (4) Jul 31, 2012
Now if they could only figure out how to prevent 90 percent of slime from concentrating in the Republican party.

Telekinetic
2.5 / 5 (13) Jul 31, 2012
@cdt and others:-

So people have forgotten Brass is a great oligodynamic material and instead go down the route of preventing formaion of (larger colonies) and issues of stickiness... Brass kills, Stainless steel door knobs in hospitals however harbour and protect bacteria. But ordinary people dont know this and like the look of stainless, education is so important, bring back brass and simultaneously increase bio-availability of zinc and copper - the two most deficient minerals in the average western diet !

Yes, some trace amounts of essential metals would rub off onto your hands, if the doorknobs aren't lacquered, which most are nowadays , so supplementation is advised. Magnesium is also showing up as a chronic deficiency in the populace. The best form is magnesium L-threonate, which is more bioavailable than previous forms and crosses the blood-brain barrier, keeping you sharp and on-your-toes for verbal battles here.
Mike_Massen
2.1 / 5 (11) Jul 31, 2012
Telekinetic claimed/guessed
if the doorknobs aren't lacquered, which most are nowadays,


Nope ! they arent, any lacquers have abrasions, cracks, great place for bacteria to hide. Stainless door knobs cleaned in hospitals with sanitisers, ie. only as good as next person to touch it.

Brass however, will *kill* the bacteria on it and depending on the type takes from an hour or so and keeps working 24/7 even if not sanitised !

Telekinetic also offered an unclear claim, please supply a ref to the organic Mg complex stated:-
Magnesium is also showing up as a chronic deficiency in the populace. The best form is magnesium L-threonate, which is more bioavailable..


IIRC, Magnesium is transported around the body by copper based proteins, one needs a good copper intake of *at least* 3 to 4mg per day. Despite homeopaths claims, chance of copper toxicity is negligible, copper pipes get covered by silicates. Food is prepared in stainless steel vessels.

Ref re Mg deficiency please ?
Telekinetic
2.5 / 5 (13) Jul 31, 2012
Here's Baldwin's website, a major manufacturer of residential and commercial door hardware. The unlacquered brass is a special order!
BALDWIN DOOR KNOBS in All Finishes| non laquered brass | satin ...
doorhardwareusa.com/list.php?cid=2580
Telekinetic
2.5 / 5 (13) Jul 31, 2012
Here's one of many sites about magnesium deficiency:

http://www.livest...iciency/
Telekinetic
2.3 / 5 (12) Jul 31, 2012
Here's a piece specifically about Magnesium L-Threonate, just one of many. Don't expect any reviews from government agencies.

http://theallheal...-update/
LagomorphZero
3 / 5 (2) Jul 31, 2012
Article: "the super-slippery surfaces have been shown to repel both water- and oil-based liquids and even prevent ice or frost from forming"

This would be great for airplanes also, assuming it can withstand the weather

TheGhostofOtto1923
1.9 / 5 (22) Jul 31, 2012
As a product where sterility is critical like an operating room, it has a future. I think, though, there is always a danger to curtailing our exposure to bacteria. It makes our immune system more vulnerable to strains of potentially deadly bacteria.


Agreed, though I do think there are a lot of places this could be useful. Breweries, for one. Milk processing plants and dairy farms for another. Indeed, in just about any place where they prepare food and require near sterile conditions.
Also drug manufacturing. How about the inside of pressure suits for extended EVA in orbit and on other planets? Perhaps this can shed regolith on the exterior of moon suits and in decontam locks as well, keeping the stuff out of living spaces.
Estevan57
2.5 / 5 (29) Jul 31, 2012
So what is the 1% of bacteria that CAN stick to this stuff? Also, is it compatible with real teeth?


That 1% would be GhostofOtto.
physpuppy
not rated yet Aug 01, 2012
@ guys talking about brass here -
any concern on the lead content of brass ?
praise139
4 / 5 (1) Aug 06, 2012
I'm a bit of a science neophyte, so please correct me if I'm wrong. A cursory reading of this article left a big question in my mind. If this surface is so slippery bacteria can't stick to it, then wouldn't that also be a deterrent to using this new substance in real world applications? Many places where we come in contact with bacteria (for instance, a doorknob or milking equipment) NEED to be touched, or gripped.
antialias_physorg
3 / 5 (2) Aug 06, 2012
Many places where we come in contact with bacteria (for instance, a doorknob or milking equipment) NEED to be touched, or gripped.

There's more ways to apply a force to an object (e.g. a door handle) than by friction. You can depress a handle/lever/button - even if its friction coefficient is zero.
Though you probably don't want to have super-slippery stuff on the floors.
Mike_Massen
3 / 5 (6) Aug 06, 2012
physpuppy offered
@ guys talking about brass here -
any concern on the lead content of brass ?
If thats really an issue, select the zinc and copper so they dont have appreciable amounts of lead. Brass door handles are sold in Australia without that issue arising...
FastEddy
1 / 5 (2) Aug 06, 2012
"SLIPS" ... What exactly is it?? Also we have suggestions for milking machines and equipment, operating room walls and furniture, brewery tanks, plumbing and equipment ... How about racing sailboat hulls? (Racing sailboats are earlier adopters fur sure ... I would buy a few gallons right now if I knew where to get it.)