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Medicine Science

Nanotech Paint To Kill Bacteria 208

Posted by kdawson
from the any-color-as-long-as-it's-white dept.
ColGraff points out reporting at Science News about the possibility of killing bacteria with paint. Scientists in the UK have found that high concentrations of titanium oxide nanoparticles in paint can kill bacteria by creating hydroxyl radicals when exposed to ordinary fluorescent light. Titanium dioxide is present in most white paint at concentrations of 30% or so, but not always at nanoparticle scale. The researchers found that an 80% concentration of TiO2 nanoparticles worked well to kill E. Coli bacteria. There is hope that the technique could be used against "superbugs," which are resistant to multiple antibiotics. A researcher not associated with the UK team pointed out the problem with developing products based on this idea: "[A]nything that survives and sticks around grows greater resistance... ultimately [antibiotic paint] will be its own worst enemy and the bacteria could grow to be even stronger."
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Nanotech Paint To Kill Bacteria

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  • by yincrash (854885) on Sunday September 14, 2008 @04:05PM (#25000707)
    titanium dioxide is in pretty much every white thing you can see. sorry dude. you even rub it into your skin for sunblock.

    Titanium dioxide accounts for 70% of the total production volume of pigments worldwide. It is widely used to provide whiteness and opacity to products such as paints, plastics, papers, inks, foods, and toothpastes. It is also used in cosmetic and skin care products, and it is present in almost every sunblock, where it helps protect the skin from ultraviolet light.

  • by compumike (454538) on Sunday September 14, 2008 @04:06PM (#25000719) Homepage

    I found an article that has much more information about the actual mechanism of the TiO2 anti-bacterial effect [nrel.gov].

    The nice thing is that the titanium acts as a catalyst, so ideally it isn't consumed in the reaction.

    The bad thing is that this requires UV light (below 385nm), which is really only present from "ordinary fluorescent lights" because they have bad phosphor coatings. All fluorescent lights really generate tons of UV, which is downconverted to visible via that white phosphor coating on the glass. But some UV escapes, and that's the stuff that triggers this anti-bacterial reaction. So good for anti-bacterial, but bad for skin cancer.

    In any case, maybe this is the kind of thing where some dedicated UV lights could turn on when no people were in a given room, and that would make for the best of both worlds?

    --
    Hey code monkey... learn electronics! Powerful microcontroller kits for the digital generation. [nerdkits.com]

  • by Eravnrekaree (467752) on Sunday September 14, 2008 @04:29PM (#25000927)

    Actually i think i heard of evidence that the titanium dioxide particles in sunscreens, especially nano particles are harmful.

    http://www.ccohs.ca/headlines/text186.html [ccohs.ca]

    "With such widespread use of titanium dioxide, it is important to understand that the IARC conclusions are based on very specific evidence. This evidence showed that high concentrations of pigment-grade (powdered) and ultrafine titanium dioxide dust caused respiratory tract cancer in rats exposed by inhalation and intratracheal instillation*"

    http://www.consumerreports.org/cro/health-fitness/nanotechnology-7-07/nanoparticles-in-sunscreens/0707_nano_sunscreen_1.htm [consumerreports.org]

    Lab studies indicate that both of those nano-ingredients create free radicals that damage the DNA of cells and possibly cause other harm as well. And even low exposure to nanoparticles of titanium dioxide can damage the lungs of animals if inhaled

    http://locokazoo.com/2008/08/05/the-sun-screen-health-disaster/ [locokazoo.com]
    http://www.nanowerk.com/spotlight/spotid=6838.php [nanowerk.com]

  • Re:Well.. (Score:3, Informative)

    by Teun (17872) on Sunday September 14, 2008 @04:34PM (#25000985) Homepage
    The old Romans tried and failed.
  • Re:Well.. (Score:3, Informative)

    by Colin Douglas Howell (670559) on Sunday September 14, 2008 @05:06PM (#25001307)
    Humans didn't evolve from cockroaches or from any arthropod. The origins of the vertebrates are currently quite obscure; something closer to a lancelet [wikipedia.org] seems the most likely candidate.

    Also, it's not clear that cockroaches could evolve immunity to boric acid while still remaining cockroaches. In other words, the biological changes required to make them resistant to the stuff could be so severe that we might not recognize the result as a cockroach.

  • by Renraku (518261) on Sunday September 14, 2008 @05:47PM (#25001791) Homepage

    Its all about resources.

    Having resistance to something takes up resources. So this bacteria might need x food, whereas its paint-resistant form might need x+3 food. If there's only x+3 food available to the bacteria, that's all it can do. It can't even reproduce because x+3 isn't enough for the cells to divide. Now, what if you slathered the wall with antibacterial soap? The bacteria would need to have soap-resistance at another +2 food, which isn't there.

    It would likely die out.

    The point isn't making the wall completely sterile, but is just making it a hostile environment for bacteria. The more a bacteria has to invest to protect itself, the less it can invest in its other traits, given a limited amount of food.

  • by tim_darklighter (822987) on Sunday September 14, 2008 @05:53PM (#25001865)
    Reading into some of your links, and being a researcher into titanium dioxide chemistry, I will tell you that the toxicity of titanium dioxide is a) nil for actual ingestion, b) high for your lungs like any small particulates, and c) unknown for sunscreen use.

    A) and B) have been known for a long time. C) is still being studied, but the results I have seen so far in peer-reviewed journals (not random health websites) show that nanoparticle sunscreens are not harmful in any real-life circumstance, and looking at your locokazoo link, the zinc oxide sunscreens are the only ones I would even consider putting on my skin. The rest are organic photo-sensitizer molecules that are more harmful than zinc oxide even without light shining on them.

    None of your links contain any scientific evidence saying nanoparticle sunscreens are harmful. Yes, titanium dioxide powder is bad for your lungs, but the titanium dioxide or zinc oxide suspended in sunscreen or mixed into paint is not particulate, and therefore has more chance of being eaten than breathed, and it is non-toxic in the digestive system. Again, no evidence has shown that the small concentration of "free" hydroxyl radicals formed when light shines on the titanium dioxide in sunscreen has any effect on exposed human surfaces.
  • by Peaker (72084) <gnupeaker@@@yahoo...com> on Sunday September 14, 2008 @07:50PM (#25003175) Homepage

    I think evolution finds creative and interesting solutions to problems that we wouldn't think of.

    I wouldn't underestimate their ability to "dramatically change their membrane" (if there is no clever way to avoid it), while also being able to live in a human body.

  • by Anonymous Coward on Sunday September 14, 2008 @10:12PM (#25004479)

    because it is too different from their usual environment that they can't adapt quickly enough, because it requires changing too many genes.

    Bacteria don't "change their genes to adapt" any more than you can "change your genes" to grow gills if the ocean level starts to rise.

    When you expose the bacteria to some "challenge" (extreme temperature, antibiotics, etc.), those not able to deal with it will die. The ones left alive are the ones that were already adapted (by pure chance, due to a mutation that proved useful). Those will then reproduce, eventually occupying the room left by those that died.

    So bacterial populations seem to "adapt", but in reality they are just undergoing a process of (natural, environmental, whatever you want to call it) selection. The bacteria didn't adapt, the weak ones just got eliminated and (over time) replaced with ones that could survive under the new conditions.

    Naturally, smaller changes in the environment are less likely to kill many bacteria, but bacteria have been found living both in arctic ice and inside volcanos, so don't underestimate their resistance (look up "extremophiles"). The chances of a bacterium in your living room being able to resist a temperature of 500 degrees are very small, but they are not zero. And if you kill all others but that one bacterium survives, you'll soon have a room full of bacteria that can survive at that temperature.

    While individual bacteria are much more "fragile" than complex life forms, like humans, their high reproduction rate leads to far more mutations, and therefore a much bigger ability to develop strains that can adapt to extreme conditions. High mortality and high reproduction rate are the "intelligence" behind natural selection.

  • by Anonymous Coward on Monday September 15, 2008 @09:45AM (#25009211)
    The paint does not decompose, it works as a catalyst. Only the water (most probably from moist air) that comes into contact with the paint is decomposed, therefore, the paint should last essentially forever.
  • by LeadSongDog (1120683) on Monday September 15, 2008 @01:41PM (#25013425)
    "The best stuff" as you call it was known as Tri-Butyl-Tin. It falls into the broad category of fat-soluble bioconcentrating persistent organo-metal toxins. Although really high concentrations are needed to kill cells, much lower levels will make whales hard of hearing or change the sex of amphibians. Each predator up the food chain gets higher concentration. Who do you think is at the top of the marine food chain these days?

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