But what happened to the control group - were they treated as well once the results were clear?
In early lab experiments on rabbits, eyedrops laced with nanoparticles appear to combat bacterial keratitis, a serious infection of the cornea which can, in severe cases, cause blindness. Researchers hope that these nanoparticles could someday offer a non-toxic alternative to antibiotics, which have the undesirable side effect …
"But what happened to the control group - were they treated as well once the results were clear?"
probably not. it's a fair bet that all bunnies (control group included) were killed and then dissected [or similar] as part of the experiment, to validate all of the results.
Yeah, being a lab animal doesn't have much of a future. Fortunately we're not going to run out of rabbits any time soon...
[keep in mind, at one point in the history of science, lab animals were being used as 'pregancy tests' i.e. "the rabbit died"]
Nanoparticles do have a slew of adverse effects, including severe inflammation and carcinogenesis. The "non-toxic" part of the claim needs to be examined carefuly in long-term experiments. Curing the bacterial infection is good except if the rabbits turned blind as a consequence!
It is good that the researchers noted that, but I think we should be more worried about what happens to the nanoparticles that get out into the environment. At least they'd be in such small quantities it would be impossible for them to have any large scale effect, but still something we should look at.
Is there anything like them in nature? Some interesting stuff is found on asteroids and comets, so if we already have something similar in very very very tiny amounts in our biosphere, there would be less reason to be concerned about adding additional very very very tiny amounts.
"It is good that the researchers noted that, but I think we should be more worried about what happens to the nanoparticles that get out into the environment. At least they'd be in such small quantities it would be impossible for them to have any large scale effect, but still something we should look at.
Is there anything like them in nature?"
Yes, in fact I am very much involved in that kind of research. Nanoparticles are found in many everyday products (from gaz additives to enhance combustion in engines, to beauty products), and their beneficial/nocive properties depend on their composition and on their size. It's still an open field, but we're working on it. Right now I work on two "opposite" projects, one aimed at curing genetic diseases with nanoparticle-mediated gene delivery, the other aimed at deciphering the pathogenicity of metal or carbon nanoparticles (such as those found in cigarette smoke or exhaust fumes) in lung pathologies, including the risk of mother exposure for the fetus. We're working on it!
Thank you for the very informed reply from someone who does research on this very subject! However, what I meant was whether there are any naturally occurring nanoparticles similar to these present on our planet, not that they are used in other products which also contribute to man-made nanoparticles in our biosphere.
I would be surprised if there are any nanoparticles created by natural processes on Earth, but I wonder if they may be present on Earth in small quantities due to piggybacking on meteors and comets that reach the atmosphere?
"I would be surprised if there are any nanoparticles created by natural processes on Earth"
Since the OP mentioned exhaust fumes and cigarette smoking, then I'd suggest that large amounts of nano particles are likely to be emitted by volcanoes and forest/bush/moorland fires.
Your question piqued my curiosity, so, since nobody seems to have answered, I went looking it up on the web; I found this rather informative article on the Royal Society of Chemistry's site: http://pubs.rsc.org/en/content/articlehtml/2015/cs/c5cs00236b . Here's a relevant excerpt:
Nanoparticles can be formed naturally via processes occurring in all “spheres” of the Earth, [...] by chemical, photochemical, mechanical, thermal, and biological processes separately or in combination, [...]. In addition, NPs are also formed spontaneously as a result of human activities (e.g., during mining, production of wastewaters and wastes in general, and other industrial processes). A recent estimate suggests the formation of NNPs, only from biogeochemical processes alone, occurs in the range of several thousand teragrams per year (1 Tg = 1 million metric tons). Comparatively, the mass of ENPs [engineered nanoparticles] produced per year is orders of magnitude lower, in the range of several hundreds to thousands of Tg per year
Since when is "in the range of several thousand teragrams per year" several orders of magnitude higher than "in the range of several hundreds to thousands of Tg per year"?
I wonder if the authors of the paper meant "several hundred thousand" was the natural occurrence, or if they mean gigagrams instead of teragrams?
Regardless, I'm glad that we have plenty of natural sources for nanoparticles. While the ones we create won't necessarily be identical to ones that occur naturally, at least biologic processes on Earth have evolved to deal with them in many forms.
What's the evidence that bacteria won't also evolve to be resistant to this treatment? All you are doing is swapping one type of chemical structure (which happens to be classified as an antibiotic) with another chemical structure. We don't know how it works, so don't know if a proportion of the bacteria population would resist it, and if they do then they will emerge as the dominant strain. If it is 100% effective then this is a double edged sword as it probably means it also kills off 'friendly bacteria' in the body.
That said any new avenues for treating bacteria is a good thing given the deadly consequences to the world if some of the current superbugs go pandemic.
Carbon seems to work below the normal biochemical level. Its action seems closer to that of a bleach than anything else (which kills by simply bulldozing cells chemically rather than by any bacterial action). You're astute to note potential risk to friendly cells, which is why I mention the specific term "A bleach," which in biochemistry means specifically an indiscriminate chemical agent (TOO powerful, IOW).
Copper is an excellent bactericide, we used to know this as all door handles in hospitals used to be copper, glad to see they have taken this into the 21st century.
I've seen the suggestion that cruise ships should have copper handrails on the stairs and other public areas to help reduce norovirus outbreaks.
copper patina isn't "shiny" (and looks old/dingy to a lot of people) and so to avoid having to polish it daily, they COULD use an alloy with a lot of copper in it, like brass, only alloyed with something (like chromium) that would inhibit the corrosion and patina.
Also boats and ships often use copper-based paint to cut back on sea growth. Otherwise, in certain areas every boat/ship would have a "grass skirt" around it all of the time.
Old sailing ships often had a band of copper plating around them, particularly warships. It didn't corrode fast in sea water, it inhibits growth of barnacles and seaweed, and it provides at least SOME armoring against cannon fire. I don't know if they used zinc to minimize the copper corrosion, though, like they do nowadays [sacrificial anodes]
and it provides at least SOME armoring against cannon fire
No it doesn't. Coppering was used to:
1 stop fouling, the growth of weed and marine life such as barnacles (which you noted)
2 prevent worming; large marine worms (a clam, actually, but it looks like a worm) would eat the wood in wooden ships, and did such a good job of it that they were named 'shipworms'. https://en.wikipedia.org/wiki/Teredo_navalis
Coppering was of ZERO value against cannon-fire because:
1 it was mostly below the waterline, and the majority of shot hit above the waterline in almost all naval actions during the age of sail. The French navy in particular had a fetish for aiming high and trying to damage the rigging of enemy, usually British, ships. At the Battle of the Virginia Capes, the French were able to do sufficient damage to British rigging that the British admiral in command elected to not press the action. This had several results, not least being that Cornwallis was forced to surrender at Yorktown. The British aimed for the hull, and tried to kill the crew rather than the sails. At Trafalgar several French ships had casualties in excess of 50%, while the top British casualties was Colossus, at 35%.
2 because of the expense of coppering, only a thin layer was used. That thin layer wouldn't stop bullets, even bullets from smoothbore muskets, much less roundshot from cannon. Stopping roundshot was why warships had thick bulwarks made of lots and lots and lots of wood, typically oak. At close range even this was insufficient, and the thick bulwarks were on the sides, not the rear (where there were stern galleries with lots of glass and thin wood) or the front (where there had to be provision for the bowsprit and forward rigging) so a warship which was 'raked' by fire from directly ahead or astern was in serious trouble. At Trafalgar, the French ship of the line Redoubtable was raked repeatedly by the British liner Temeraire when Temeraire came to the rescue of Victory; at least 300 of Redoubtable's 800 or so crew were killed by roundshot and grapeshot at close range. (Note that Temeraire was named for a French ship which had been captured by the RN in an earlier war. There were three Neptunes at Trafalgar, one in each of the British, French, and Spanish navies, and a British Tonnant and a French Swiftsure.)
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