Materials

Spiky stainless steel and copper delivers one-two punch to bacteria

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Even thick-skinned bacteria is no match for the copper-coated spiky surface of the etched stainless steel, as illustrated in this exaggerated rendering of the material
DALL-E
Even thick-skinned bacteria is no match for the copper-coated spiky surface of the etched stainless steel, as illustrated in this exaggerated rendering of the material
DALL-E
The work was led by postdoctoral scholar Anjua Tripathi from Georgia Tech's School of Chemical and Biomolecular Engineering
Georgia Tech

To help combat the rise of antibiotic-resistant bacteria, researchers have been experimenting for years with drug-free methods to blast disease-causing bugs. A new type of stainless steel does exactly that, in a convenient and affordable way.

According to a global survey described in the journal Nature, in 2019 alone, antibiotic-resistant bacteria killed more people than HIV/AIDS or malaria. The superbugs were implicated in nearly five million deaths, directly causing over 1.27 million fatalities. A report from the UN's Environment Programme says that the WHO lists antimicrobial resistance (AMR) as one of the top 10 global threats to health, and that by 2050, up to 10 million additional deaths could be caused by bugs that have evolved to avoid our drugs. That would be on par with the number of global deaths from cancer in 2020.

Understandably concerned about numbers like these, researchers from Georgia Tech set out to attack AMR mechanically instead of chemically. In particular, they sought to combat Gram-negative bacteria such as E. coli, cholera, and salmonella because they contain a protective capsule that makes them particularly good at fighting back against traditional antibiotics.

"Killing Gram-positive bacteria without chemicals is comparatively easy but tackling Gram-negative bacteria poses a significant challenge, due to their thick, multilayered cell membrane," said Anuja Tripathi, the study’s lead author. "And if these bacteria persist on surfaces, they can grow rapidly. I aimed to develop an antibiotic-free bactericidal surface effective against Gram-negative and Gram-positive bacteria."

The work was led by postdoctoral scholar Anjua Tripathi from Georgia Tech's School of Chemical and Biomolecular Engineering
Georgia Tech

Using an electrochemical process, Tripathi's team etched the surface of stainless steel to create thousands of tiny microspikes. They then bonded copper ions to the surface of the steel, again using electrochemistry. The result is a material that blasts AMR bugs two ways. The spikes shred their protective outer membranes, and the copper – which has been known for its antibacterial qualities since ancient Egyptian times – further degrades their cellular membranes.

In tests, the steel and copper material reduced Gram-negative E. coli by 97% and led to a 99% reduction in Gram-positive Staphylococcus epidermis bacteria. The material was shown to achieve these results in only 30 minutes.

The fact that the new material only contains a very thin layer of copper means it sidesteps the high cost of the material, thus keeping the new steel/copper combo affordable. And because it shreds bacteria with its spikes, it should keep the bugs from evolving the means to escape death, as they can do with chemical treatment methods.

This is not the first time we've seen materials that use mechanical methods to shred resistant bacteria. This year alone, we've reported on a spiky titanium material inspired by dragonfly wings that shreds a common respiratory virus, and spikes on a nanocrystal that spin up under light to dice up bacteria. The Georgia Tech study takes things a step further with the addition of copper and, based on the dire warnings of health agencies regarding AMR, can we really have enough ways to fight the attack of the superbugs?

The research has been published in the journal, Small.

Source: Georgia Tech

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8 comments
John S
How does this kill the bacteria? Is it used as a coating on a pill? Does blood have to go through a filter? (sort of like a transfusion?) Is the product an implant? It is put on a grain in a capsule? I do not understand? Help.......
WONKY KLERKY
ANOTHER REINVENTION OF THE WHEEL.

Does none remember the days of public building door furniture of Brass + Bronze + Gunmetal + Straight forward Copper ?
+
ref Ye Plumbing:
for an eg / 2:
Copper piping with brass fittings?
Copper ball-cock floats?
+ + +
OH BRAVE NEW DOORS & BOGS !
RobertElliot
John S I share your confusion. I cannot imagine how it would be used in practice either.
martinwinlow
RobertElliot & John S - I think (the rather fantastic) WONKY KLERKY understands how this material would be deployed and, essentially, anything likely to come into contact with bacteria in a medical context is applicable ie it would be either made of or coated with the 'idea'. So, surgical implements, operating theatre (if not hospital fixtures and fittings in general) surfaces, containers, surgical implants (?), etc, etc... But it would have been helpful for the article to cover this question!
PoconoPuppy
I'm thinking shared items such as doorknobs, water fountains, vending machines, elevators, etc. I'm assuming the human touch won't feel it or affect it.
Karmudjun
Michael - nice article. Your facts are spot on, but you are short on how this really looks. Having worked in surgery - where actual operations occur - I can see the utility of back tables and PT equipment and gurneys and so forth all made with a think layer of this material. So how big are the spikes? Is this measured in nanometers? It certainly isn't as big as micrometers. Copper and Silver have been destabilizing gram bacteria forever, but not gram-negative bacteria in-spite of WONKY-KLERKY's comment. This most certainly is NOT a reinvention of the wheel, it is a refinement of a stone wheel into a flat-less wheel with a motorized rim. It is definitely a leap forward if the production can be scaled up to commercial size - restaurant prep areas, hospital staging areas, even surfaces inside space capsules or space stations. Heck, in the old days of disinfecting our dairy pails when we hand milked our cows (yes, I'm that old), buckets with this surface coating would have been a blessing!
Lamar Havard
Great, the bacteria gets squished between your hand and the doorknob. I guess bacteria guts are better than whole bacteria.
WONKY KLERKY
And another consideration:
ref:
'The fact that the new material only contains a very thin layer of copper means it sidesteps the high cost of the material, thus keeping the new steel/copper combo affordable. And because it shreds bacteria with its spikes - etc':

Errrrrr, wot happens when the cleaner gets the Brasso* out?

* Other cleaning agents are available.