Dual antibacterial properties of copper-coated nanotextured stainless steel | Hacker News Reader

Dual antibacterial properties of copper-coated nanotextured stainless steel

onlinelibrary.wiley.com

107 pointswesturner117 comments

As someone that has built and operated large multipractice and acute care facilities some of the most vicious fights I've had with medical entities and boards is about changing hardware back to the older brass/copper which is inherently antibacterial and only needs cleaning with soap/water to self disinfect versus stainless steel which needs cleaning with bleach and can foster or even lead to the creation of resistant and other problematic bacteria. The objections were mostly about the visual appearance. I am not sure I see the advantage to this new material over the good old brass/copper. There is a perceived cost premium to it but it isn't meaningful in practice. This paper alleges this new process is cheaper but I would be incredibly dubious of that. At ClearHealth we were successful in substantially reducing hospital acquired infection (HAI) rates at managed facilities to industry best in part because of our "reversion" to copper/brass hardware.

One of the most obvious signs you are in a well managed health system is seeing copper/brassy touch surfaces instead of stainless.

https://www.copper.org/publications/newsletters/ba-news/2010... https://en.wikipedia.org/wiki/Antimicrobial_properties_of_co... https://www.statnews.com/2020/09/24/as-hospitals-look-to-pre...

From the Wikipedia page:

> The oligodynamic effect was discovered in 1893 as a toxic effect of metal ions on living cells, algae, molds, spores, fungi, viruses, prokaryotic, and eukaryotic microorganisms, even in relatively low concentrations.[7] This antimicrobial effect is shown by ions of copper as well as mercury, silver, iron, lead, zinc, bismuth, gold, and aluminium.

So I can justify wearing a bunch of oversized gold chains as “for my health”?

Go the whole-hog and dip yourself in mercury.

Terracotta army style. I like it!

Yes, and that means you can buy the jewelry with FSA/HSA funds

Do the useful properties of copper change with oxidation?

Silver is also antimicrobial, and also expensive.

FWIU nanospikes in silicon achieved virucidal outcomes in small trials as well.

Is copper virucidal without nanospikes?

(On this topic, Hemp textiles are antimicrobial / bactericidal: https://news.ycombinator.com/item?id=39196781#39197019 )

"Scientists create virucidal silicon surface without any chemicals" https://pubs.acs.org/doi/10.1021/acsnano.3c07099 https://news.ycombinator.com/item?id=39196822

Oxidation is a problem as is physical debris but touch surfaces are cleaned at least daily in a hospital setting anyway. Plain old Copper/brass that has been used since forever is virucidal without any special treatment.

Is the claim then that copper nanospikes on stainless steel are of no greater value than copper for healthcare applications?

Is that claim supported by evidence?

The claim is that spikes kill faster, but probably not fast enough to matter since spikes are destroyed with shear cleaning.

A frequently touched surface isn’t going to have a problem with oxidation:

https://en.m.wikipedia.org/wiki/Statue_rubbing

So the people rubbing breasts of statues to a shine were doing it for uh... serious reasons?

For medical reasons thank you very much

You should see the brass bull on wall st

I looked at the wiki article but it did not touch on the anti-bacterial effects. Are there any studies?

P.S. I am really curious (if just mildly) if anyone knows.

Edit: Ok it did touch on the subject.

"It is also possible to acquire a bacterial infection from touching statues."

The is even a reference to an article (https://atlasbiomed.com/blog/european-biome-monument-study-r...). Have not read yet but looks interesting.

Copper and silver express the "oligodynamic effect," a tendency for antibacterial action, most strongly.

Brass is a useful alloy of copper that does not oxidize and also exhibits this effect.

https://en.wikipedia.org/wiki/Oligodynamic_effect

Nosocomial infections are terrifying because they're often things that have as you said survived in a very harsh environment. Thank you for doing your part to reduce them.

Set up a company selling remarkably over-priced “medical” door handles and healthcare providers will fall over themselves to buy them.

Copper is of course, chemically incompatible with most disinfectants and cleaners and will corrode. Which is one reason it stopped being used when ammonia/etc became super common. They are less common now in straight form (even Windex is no longer mainly ammonia unless you use the original formula version)

So solid copper/brass i can get behind because it probably doesn't affect lifetime meaningfully, but I am very curious how the coating in the article withstands splashes of ammonia or peroxides or other things used to clean the floors or windows.

I was wondering about this too, it's not viable to have a coating which necessitates changing equipment periodically. It will add logistical problems and waste. I think you are right in that using solid metals instead, makes more sense, given antibacterial properties have been known to exist for these for a while. The question is if all types of pathogens can be removed without damaging the equipment, or if material research could create an alloy which just like stainless steel, could make the metal form an oxidation layer which would protect it in case of contact with corrosive liquids.

Wood also has excellent antimicrobial properties e.g. makes a much safer cutting board than plastic

...but you can easier wash plastic in the dishwasher, while wooden cutting boards get warped and destroyed.

Wash wood or eat microplastics from the cutting board.

Changing handles in busses/trains from metal to plastic probably killed more people than a lot of other common causes. Everyone is touching those things, they are dirtier than cash.

50-75 years ago, brass handles were the norm on public buildings like schools, government buildings, factory buildings, hospitals, etc.

Can we please stop changing things that don't need to be changed?

Copper gets stolen a lot these days. Even from cables. So door handles might not be the best idea.

Brass handrails and large door handles do regularly get stolen here.

The solution is to punish and prevent theft, not to give up.

Both of those are hopeless as the US crime stats show despite the medieval punishment system.

It's more about preventing the root cause of crime: culture and economy.

Medieval? Have you seen a prison elsewhere in the americas in comparison? America is like a glowing bastion in comparison.

Exactly. As inflation goes up and wages remain stagnant, more and more people are doing the risk calculus that makes stealing and crime in general worthwhile.

People with good paying jobs that don't wear them down the bone don't steal things, but when you're looking at spending 90% of your pay on a shared living space, and no money left for food, or emergencies, then stealing copper, or catalytic converters all of a sudden starts looking like a valid option.

Which unfortunately is not a solution since harsher punishments have shown to not prevent crime.

Harsher punishments are not as important as reliable enforcement. Harsh punishments that are reliably enforced are very effective, but we generally can get a "good enough" result with more moderate punishments, reliably enforced.

You’d have to use some pretty extreme measures like permanent removing every thief and every person buying copper from thieves from society so they can never steal again.

Anything less isn’t going to stop it. See drugs… the death penalty for drug use is extremely effective. It’s also horrific but hasn’t stopped us before, so why should it stop us now?

Huge battery shocks if the handle is removed. Then send the thieves to Australia.

Your societal reference frame is bad and you should feel bad. Gilded age had all the punishments and stil humanity worked all things unguarded like a corrosive material. Which meant, all things public were burdened with a anti theft tax, a guy with a stick. Which is why it makes economically sense to pay a thief to sit at home and play video games, as otherwise you would need to hire him, to guard a bridge. Non surplus societies aint pretty.

What happens if you breathe the coating in?

Copper toxicity > Signs and symptoms: https://en.wikipedia.org/wiki/Copper_toxicity#Signs_and_symp... :

> The US EPA lists copper as a micronutrient and a toxin. [11] Toxicity in mammals includes a wide range of animals and effects such as liver cirrhosis, necrosis in kidneys and the brain, gastrointestinal distress, lesions, low blood pressure, and fetal mortality. [12][13][14] The Occupational Safety and Health Administration (OSHA) has set a limit of 0.1 mg/m3 for copper fumes (vapor generated from heating copper) and 1 mg/m3 for copper dusts (fine metallic copper particles) and mists (aerosol of soluble copper) in workroom air during an eight-hour work shift, 40-hour work week. [15] Toxicity to other species of plants and animals is noted to varying levels. [11]

A reasonable production process would need to contain and could probably reuse copper emissions

If you ever spend time within a few hundred meters of other cars such as while driving around or walking along a road you are inhaling large amounts of aerosolized metal particles from brake dust. If you want a large sample to verify this phenomenon, pull up to a semi tractor trailer as the truck brakes to a sudden stop such as when slowing down on the freeway upon hitting heavy traffic and take a good whiff.

Are they specifically engineered to be deadly to cells, though?

Can you explain the relevance of this question? I think it’s likely I’m missing something, but your question sounds like: “Yes, volcano eruptions have killed innumerable people and species…but were they _specifically engineered_ as killing machines?? Gotcha!”

here's the relevance :

a bow and arrow and a gun both shoot projectiles. One of them has more regulation due to improved efficacy at shooting projectiles.

The presumption here would be that the materials designed for killing cells would do so in a drastically better fashion than materials that are designed for better brake performance but which also coincidentally shed harmful particles.

Using your concept : it would raise questions if we heard about a human-lead effort to develop the most cataclysmic volcano eruption ever produced.

I didn't get the premise that it's supposed to be a gotcha; it's not. It's just a different thing. We gain benefit from better brakes, it's not all loss.

Engineered? It's metallic copper.

And “nanotextured stainless steel”?

Asbestos is just… rock.

Yes. They etched stainless steel.

I'm not seeing the comparison to asbestos which is dangerous regardless of form.

Asbestos is dangerous because of its form. It isn’t inherently toxic, it just pokes your lung tissues to death.

This is why I find a new material with “nanoprotrusions measuring 20–30 nm” in an article talking about “nanodaggers” killing cells somewhat concerning.

Specifically SiO2 which does not dissolve

Is rock safe?

Against scissors, yes.

But at these length scales these materials are very corrodable, even stainless steel. They wont last long in the body.

Unlike, say, textures silica that was on here a few months ago. Then I raised this exact concern since SiO2 wont just disappear.

How much longer do brake pads on trucks with regenerative braking last?

Though, wouldn't a differently shaped initial acceleration torque curve save synthetic tire microplastics from the ocean, while we figure out how to make dandelion rubber tires?

Last time I went in the dude mentioned offhand that my current model of brake pads wouldn’t be for sale by the time I needed new pads because mine were sintered (with?) copper.

Might be state by state but sounds like it’s on people’s radar at least.

As an aside, an argument in favor of mass transit vs electric cars, is that EVs do nothing to reduce particulate matter pollution from tires and breaks.

> is that EVs do nothing to reduce particulate matter pollution from tires and breaks

Except for not using brakes for the most part. EV brakes typically last for the life of the car.

https://en.wikipedia.org/wiki/Regenerative_braking

And your tires?

Your quote:

> EVs do nothing to reduce particulate matter pollution from tires and breaks.

"Substantially reduce particulate matter pollution from brakes" sounds like doing "something", not "nothing", to me.

Which is why I used a logical conjunction.

https://www.oecd-ilibrary.org/sites/4a4dc6ca-en/1/3/3/index....

If one thought EVs did something help with one of the two, they'd have omitted it from the list of things "EVs do nothing" to help with.

Something that helps with X cannot be said to do nothing to help with "the problem of X and Y". If they reduce it for tires, then they do reduce the problem of "particulate matter pollution from tires and breaks" - proportionally to how much the latter contributes to said problem.

Um, no.

https://ocw.mit.edu/courses/24-241-logic-i-fall-2009/

Good luck.

And the link to a logic course somehow proves you right for saying "EVs do nothing to reduce particulate matter pollution from tires and breaks"?

Dude, you just pulled the weird-ass argument about "that's why I used a conjuction" in a hail Mary attempt to pretend you already knew about them reducing break pollution.

As if any person who actually knew EVs reduce particulate matter pollution from breaks would ever say: "EVs do nothing to reduce particulate matter pollution from tires and breaks" - implying they meant "they don't reduce BOTH" all along.

Seriously, sign up for the course. You would benefit.

EVs don't do that, regen braking does that. Regen braking can be fitted to hybrid or ICE cars.

Well, you were the one who grouped them. The reality is that EVs wear tires equivalently fast to other similar weight vehicles and wear brakes very very slowly. And reduce carbon emissions. And noise.

I grouped them together,because overall EVs appear to have marginally less non-exhaust particulate matter pollution than gas vehicles:

https://www.oecd-ilibrary.org/sites/4a4dc6ca-en/1/3/3/index....

In other words, the road to a mostly pollution free transit future will be laid with tracks rather than asphalt.

It will be laid by first understanding reality, which includes the enormous road network we have today and the social motivations to expand it. Just bleating about how great it would be if everyone used transit isn’t going to change a damn thing.

EVs are a solid and realistic step towards reducing our worst pollution problems. Widely available car sharing and autonomous vehicles would be a great solution to the last mile and even reducing the problem of so much space being used for parking, while improving the walkability of our cities. Look towards possibilities that can work, instead of clinging to models that can’t address the problems of today.

Don’t be silly. EVs, ride shares, autonomous cars, etc.. are a poor transit solution within dense cities, where a significant if not overwhelming majority of car use occurs. These urban environments are ripe for cost effective, efficient mass transit solutions, such as the BRT system Mexico City recently implemented. They absolutely address the problems of today.

Dense cities are only one type of population center. There are suburbs all over the world, there are diverse forms of low population areas, and there are frontiers. The majority of car use is not in city cores, it is in the medium to low areas all over the world, which is by far the dominant land use pattern by area.

Never in America. We live too spread out, and many cities lack coherent work centers.

Depends on if you are doing a lot of acceleration pulls with that sports package you paid extra for in your tesla.

Maybe if you drive like a grandma and not like I see a lot of people with these 4 second 0-60 cars drive are you avoiding the brakes.

Thanks to regenerative braking, my brake disks rust long before they wear out. Tire particulates are an engineering problem that will be solved long before the social problem of convincing people to live close enough to make public transit practical.

And your tires?

I'm never going to take public transit in the United States if I can help it because there are too many unhinged psycopaths and it takes just one. When I visit Europe it's all I take day in day out. Except certain parts of Paris and the UK which have had lots of recent arrivals. But even the new arrivals are less insane than many of the characters found on US public transit.

As opposed to in traffic? Plenty of road raging psychos out driving cars.

The conclusion is that the US just has more psychos. But the restraint of wrecking their vehicle to accost me holds them in line. On public transit they can accost me and nothing stops them.

Here in Austin people shoot at eachother on the highway all of the time, there's no need for them to wreck their car

Let's be real for a minute; the relative incidence rate of highway shootings is far lower than the relative incidence rate of violent crime on public transit in American cities.

My not-sufficiently-informed opinion is in agreement with yours. Do you have any studies that we can use to compare shootings versus violent crime rate on public transit?

A quick Google search revealed some data collected by the US government on the topic.

https://www.bts.gov/content/reports-violent-crime-property-c...

You have to be a hermit in a cave if you want to actually do that. Those same people you worry about are also in the grocery store, in the parking lot, at the airport, on the sidewalk, walking around your property. Really there is no added risk in taking transit because you’ve already taken on the risk anywhere else public facing. If anything there’s less risk on transit than many other places you’d find bad characters considering there are surveillance cameras, witnesses, and a driver whose job it is to call the police.

Nope, I lived in downtowns for ten years: Houston, Miami, Denver, and New York City. I've had enough.

Violence and "crazy" people tend to be clustered in certain areas and not spread generally among the populace. For example, I bought a house in a "genteel" part of a mill town. In other words, the houses are maintained. 2 miles away in the "mill worker" section of town (not very well maintained housing) we've had numerous reports of violence, and one or two murders.

I can go to my local supermarket, Home Depot, drugstore, ice cream stand and never encounter any violence. Travel on the bus however and well, the police reports say it's a different story. With the reality? Not sure but every time of been on public transit, it's a cluster of "crazies" mixed in with the general populace.

What this tells me is the problem is not public transit or urban spaces. We need to build a more humane city like what they have in Scandinavia (high public trust, services to keep you from being desperate, respect for common individual property) and the risk of violence will drop both in city spaces and on public transit.

Unless there's a ramification of electromagnetism that I'm missing, cars that do the bulk of their braking through regeneration require their conventional brakes to absorb far less energy, reducing the particulate matter generated.

However they're much much heavier, generating more tire and brake dust.

And unless the mass transit is tireless, it will be even heavier. Tire wear and this microplastics go up with the square of axle weight, so individual transportation is actually better from that standpoint.

But mass transit carries more people per wheel, and the weight of the bus does not scale linearly with the carrying capacity, so it doesn't automatically follow that "individual transportation is actually better...". I doubt that 50 EVs carrying one person each generate less tyre wear than one bus carrying 50 people.

Road damage is a function of the power of 4[1] generally.

A BYD bus weighs 18 tons and carries 32 people including the driver. [2]

A BYD Atto 3[3] carries upto 5 people and weighs 1.8 tons unloaded.

The proportional road wear function of the BYD Atto would be about 10 (1.8^4). For the bus it would be (18^4) 104,976.

So the bus is 10,000 times more wear then the car. Per passenger it's 3000 wear units for the bus versus ~10 for the car.

[1] https://en.m.wikipedia.org/wiki/Fourth_power_law

[2] https://en.m.wikipedia.org/wiki/BYD_K_series

[3] https://ev-database.org/car/1782/BYD-ATTO-3

Roads are for walking, bicycling and repair/cleaning/utility/emergency services. Deliveries go by subterran pallet-delvicery networks, to be last-miled by freight-cycles. Mass-transit by rails. Long-transit by maglev or air.

Fuck cars!

This only works where the population has a very high average IQ (ability to understand second and third order effects of long expensive projects), no anti-social behavior (no corruption or theft in public works projects), with politicians whose interests align with the people. Unfortunately we live in a world where you will be stabbed to death and robbed for walking down the sidewalk holding a $20 bill openly in your hand.

There are regional differences to that sort of behaviour.

The average car carries 1.2 people, how many does the average bus carry?

The 10 number is for literally one person, I'm also discounting their mass (this isn't a precision exercise).

If you add 5 people to the car, call it 80kg per person so your you goto about 2.2 tons, then the damage number would be about ~24, but divided by 5 you end up with 4.8 (so a fully loaded car does about half the damage per person compared to one with a single occupant).

The thing is of course on some level this is large scaling factors applied to small numbers - i.e. tires still don't fail that quickly anyway, neither do roads.

Conversely it is actually weird to see that on this one metric, numerous self driving EV taxis is actually better.

>Road damage is a function of the power of 4[1] generally.

Per axle. So for instance, if you're comparing an 18-wheeler to a 4-wheel car you have to compare (truck-weight/9)^4 to (car-weight/2)^4. Or ((truck-weight/9)/)car-weight/2))^4

So if a bus was an 18-wheeler, it would be about 16x the wear units, /32 passengers brings it to half.

It doesn't make a difference for the bus you linked, since it's also a 4-wheeler like cars, but if we cared we could add more axles to buses.

But, why don't we do that already? Apparently...

1) regulations don't require it

2) we sort of already do; some buses have rear wheel bogies that have 4 wheels of which 2 are kept raised at lighter weights. Which is basically all the time because regulations don't require it.

3) more wheels reduces fuel efficiency (and costs more money), obviously

4) wheels take up space and reduce passenger capacity, which make the bus less efficient if you don't care about road wear

5) buses have a much more consistent weight load than trucks, since ~30 passengers would be only 3 tonnes of difference.

I'm wildly out of my depth on buses/trucks here, so if a mechanic could chime in on bus/truck weight distribution and wheels that'd be great.

Subways produce a ton of particulate too. Stations are always dusty and transit operators don’t seem to care about investing in better ventilation for the platform.

I did some research and it seems this is already a problem with ICE vehicles because of the pickup/SUV trend.

I don’t know how precise this data is, but apparently the top selling models in the US are [1]:

1. Ford F-150 (1,846–2,584 kg)

2. Chevrolet Silverado (2,029–2,272 kg)

3. Toyota RAV4 (1,530–1,640 kg)

4. Tesla Model Y (1,884–1,998 kg)

5. Honda CR-V (1,500–1,681 kg)

6. Dodge Ram (2,176–3,418 kg)

7. GMC Sierra (2,029–2,272 kg)

8. Toyota Camry (1,480–1,660 kg)

9. Toyota Tacoma (2,007–2,032 kg)

10. Tesla Model 3 (1,611–1,836 kg)

They do seem to average 200-300 kg more than a comparable ICE model but as a whole they’re not tremendous outliers.

[1]: https://www.edmunds.com/most-popular-cars/

Very interesting, thank you for sharing the numbers

ICE vehicles are getting larger because they're exempt from fuel economy requirements.

You can do the same by engine braking with a stick shift, tapping the break only to hold you still at the end if you really wanted to. And the car could be a 2000lb subcompact.

Regenerative braking means that if you drive them right EVs can have factory brake pads at 100k+ miles that look new. https://x.com/niccruzpatane/status/1785043593427640326

This also allows for use of drum brakes, which have rare issues of overheating when used alone but are fine with regen doing most of the work. Those contain the abrasion materials within themselves.

Some EVs already use them but to become common it'll probably require new regulations like the EU is planning to overcome the "ugh factor" because they used to be the cheap, low end options.

In what scenario would you be exposed to the aerosolized coating, assuming it is aerosolized at all?

The history of ewaste recycling is horrifying and is worth thinking about before making more in the future. And I’m using ewaste as the friendly term for hazmat/hazardous materials. All too often they end up in a huge burn pile that uneducated impoverished children set on fire and then climb and forage in.

Same scenarios I'm exposed to Teflon; widespread use everywhere long before we know the safety profile. If it's effective, folks are going to want it in hospitals, school buses, hand railings at public places, elevator buttons, the works.

It took decades for the risks of PFAS materials to properly surface.

Copper has a very long safety record. Comparing it to PFAS is ridiculous.

I’m more wondering about the nanotextured steel.

You're right to be concerned. Material innovators should be open about these things.

Copper is toxic, but at these levels shouldnt be a concern.

Nano stuff are nasty, but since copper in the body cannot last long (corrosive environment), the nano particles will quickly disappear.

This is likely to be far more benign than other nano materials.

The question is, will this survive outside a lab?

It depends on what's being compared. Anything that has a known negative effect that is intentionally suppressed in order to maximize profits all fall into the same category to me regardless of that the "it" actually is. At the same time, we have plenty of historical evidence where a new thing was thought to be the greatest thing since sliced bread and rushed to market only to be found that it is pretty nasty stuff. We can now test the new thing much more rigorously if only someone wants to spend the money and possible delay in profits which is no company ever.

Copper is not safe, which is kind of the point.

That safety record says that copper dust/particles are definitely toxic to humans and there are plenty of instances of it getting into things it should not so I'm not sure what you are trying to say.

If copper found its way into everything as invidiously as pfas has, that would be really bad

The safety record says elemental copper dust is an irritant outside very large doses and acute toxicity happens at levels above a gram.

Copper is already everywhere at levels far, far above PFAS. It is found naturally in all plants and animals and it has been used for everything from coinage to water pipes for upwards of six millennia.

Teflon - poly(tetrafluoroethylene), is used in medical implants in the human body.

I wouldn't about it.

PFAS? That's different.

Plutonium is also used in medical implants; it remains toxic. https://osrp.lanl.gov/pacemakers.shtml

https://en.wikipedia.org/wiki/Polytetrafluoroethylene

> PTFE is one of the best-known and widely applied PFAS commonly described as persistent organic pollutants or "forever chemicals".

The plutonium in a pacemaker isn’t constantly bathed in your body fluids.

PTFE is 100% inert unless heated. It’s the reason why it’s used in joints and stents.

In other words, a material's safety may depend on the context in which it is used. I have concerns that a copper-coated nanotextured steel might, in some scenarios, have human health impacts; I'd rather not learn about it after decades of widespread use like PFAS.

Don’t hold back progress based on unfounded fears.

That industry won't properly test for safety and hide evidence as long as possible is not unfounded.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10237242/

> Our review of industry documents shows that companies knew PFAS was “highly toxic when inhaled and moderately toxic when ingested” by 1970, forty years before the public health community. Further, the industry used several strategies that have been shown common to tobacco, pharmaceutical and other industries to influence science and regulation – most notably, suppressing unfavorable research and distorting public discourse.

"Dual Antibacterial Properties of Copper-Coated Nanotextured Stainless Steel" (2024) https://onlinelibrary.wiley.com/doi/10.1002/smll.202311546 :

> Abstract: Bacterial adhesion to stainless steel, an alloy commonly used in shared settings, numerous medical devices, and food and beverage sectors, can give rise to serious infections, ultimately leading to morbidity, mortality, and significant healthcare expenses. In this study, Cu-coated nanotextured stainless steel (nSS) fabrication have been demonstrated using electrochemical technique and its potential as an antibiotic-free biocidal surface against Gram-positive and negative bacteria. As nanotexture and Cu combine for dual methods of killing, this material should not contribute to drug-resistant bacteria as antibiotic use does. This approach involves applying a Cu coating on nanotextured stainless steel, resulting in an antibacterial activity within 30 min. Comprehensive characterization of the surface revealing that the Cu coating consists of metallic Cu and oxidized states (Cu2+ and Cu+), has been performed by this study. Cu-coated nSS induces a remarkable reduction of 97% in Gram-negative Escherichia coli and 99% Gram-positive Staphylococcus epidermidis bacteria. This material has potential to be used to create effective, scalable, and sustainable solutions to prevent bacterial infections caused by surface contamination without contributing to antibiotic resistance.

- "This modified stainless steel could kill bacteria without antibiotics or chemicals" (2024) https://phys.org/news/2024-05-stainless-steel-bacteria-antib...

"Scientists create virucidal silicon surface without any chemicals" (2023) https://news.ycombinator.com/item?id=39196781#39196822 :

"Piercing of the Human Parainfluenza Virus by Nanostructured Surfaces" (2024) https://pubs.acs.org/doi/10.1021/acsnano.3c07099 :

> We used reactive ion etching to fabricate silicon (Si) surfaces featuring an array of sharp nanospikes with an approximate tip diameter of 2 nm and a height of 290 nm. The nanospike surfaces exhibited a 1.5 log reduction in infectivity of human parainfluenza virus type 3 (hPIV-3) after 6 h, a substantially enhanced efficiency, compared to that of smooth Si.

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