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Nanotech Paint To Kill Bacteria
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."
What a crazy thing to say. It's true, for sure, but has always been the case in the arms race against bacteria. It's what natural selection does...
What could possibly be the researcher's motivation to say such a strange thing?
*cough*She's the founder of a rival nanotech firm*cough*
A coincidence, or fear mongering unscientific FUD? You decide!
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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.
I found an article that has much more information about the actual mechanism of the TiO2 anti-bacterial effect.
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?
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A researcher [...] pointed out the problem [...]: "[A]nything that survives and sticks around grows greater resistance"
If those were his words, then I guess this "researcher" needs to do a bit more research, perhaps starting with a book written by a certain "Charles Darwin".
If the bacteria "stick around" it's because they are already resistant. Meaning they get to multiply, not to "grow greater resistance" (if they survived, their resistance is as "great" as it needs to be).
All that antibiotics do (in the long run) is change the relative populations of different kinds of bacteria (eliminating the ones that aren't resistant, leaving more room and resources for the resistant ones to grow). They don't actively make bacteria "get stronger", as the quote suggests. It's not as if the bacteria send a sample of the antibiotic to their underground lab where bacterial boffins come up with an antidote. They don't even have proper immune systems.
It's annoying when even "scientists" attribute some sort of "guiding intelligence" to the process of natural selection (or to individual bacteria, for that matter).
P.S. - And yes, I'm aware of plasmids, but bacteria can't suddenly rush out to buy some when they need them [ * ], so it's still a matter of selection, not "self-improvement".
[ * ] Unless they're playing Bioshock.
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
"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
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/
http://www.nanowerk.com/spotlight/spotid=6838.php
The problem here is British, a historical lack of hygiene.
The paint proposed could be a solution but I doubt whether they'll ever be able to recuperate the investments by lack of an export market...
Another issue is that by now it's known nano particles are potentially in the same league as Asbestos fibres and spreading them on large surfaces might introduces other problems.
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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.