Elemental silver would be plain metallic silver. Nanocrystalline Silver is:
http://www.nucryst.com/platform_technology.htm Nanocrystalline Silver "NUCRYST's platform nanotechnology is based on materials that on conversion to nanoscale exhibit different physical properties from bulk silver or other noble metals. NUCRYST scientists accomplish this using a process called reactive magnetron sputtering, which is a form of physical vapor deposition. In a vacuum chamber, pure silver is bombarded with positive ions to liberate or sputter individual atoms. The silver atoms are activated by an entity known as a plasma, often referred to as a fourth state of matter. These silver atoms are then re-condensed to form new high-energy nanocrystalline structures on substrates - such as high-density polyethylene for non-adherent wound care dressings. NUCRYST has also developed proprietary methods to produce free-standing nanocrystalline powders. Silver is the first noble metal being targeted by NUCRYST for the application of the nanocrystalline technology. Conventional silver is composed of large crystals, usually micro-crystallites (1 or 2 microns). These micro-crystallites dissolve slowly, thereby limiting the available silver. By contrast, the silver used in NUCRYST Pharmaceuticals' existing medical devices and emerging pharmaceutical product line is made up of much smaller crystals of silver (between 1 and 100 nanometers). Compared to bulk material silver, NUCRYST’s silver in nanocrystalline form is in a higher energy state and exhibits enhanced solubility." I don't think the study tells the whole story as is the case with so many studies. Not that the studies are incorrect or biased but the studies are necessarily focused and cannot address the whole spectrum of issues affecting a subject. For example, I have seen studies with pictures showing a silver particle enveloped within a bacteria and I would expect that at some point in time the silver will emit an ion that destroys the bacteria. I also read a study showing an HIV-1 virus with each of its 26 binding points each occupied by a silver particle, thereby preventing the virus from attaching to a host cell and rendering it harmless. (I don't know if a silver compound would act the same way.) So silver particles can in effect kill bacteria and viruses but not as effectively as a silver compound. One thing I found interesting in the report, if you read the whole report in Google Books, Is the statements that silver compounds in general are antimicrobial including silver oxide which I had considered somewhat inert. I had recently thought that silver chloride was getting a bad rap in general. At one time I did think that silver chloride was undesirable based on what I had seen from some old Frank Keys posts. But it looks like the most recent studies support ionic silver and silver compounds over silver particles. Not that all silver compounds are equally effective. The study I have previously posted on silver citrate showed that silver citrate can be much more effective than silver nitrate and I expect that others are as well. I would like to add an additional extract from the study " Chemiosmotic Mechanism of Antimicrobial Activity of Ag+ in Vibrio cholera". http://www.ncbi.nlm.nih.gov/pmc/articles/PMC127333/ "In summary, the addition of low micromolar concentrations of Ag+ to inside-out membrane vesicles of V. cholerae induced a total collapse of both ΔpH and Δψ irrespective of the presence of Na+ ions. This effect of Ag+ was independent of the presence of the Na+-translocating NQR, known as a specific target for submicromolar Ag+, suggesting that the other Ag+-modified membrane proteins (or perhaps the Ag+-modified phospholipid bilayer itself) can cause the H+ leakage, thus explaining the broad spectrum of the antimicrobial activity of Ag+ ions. ... Thus, finally, the controversy over the mechanism of the bactericidal activity of low concentrations of Ag+ ions has been clarified." It is important because it may explain the broad antimicrobial activity of low concentrations of ionic silver. - Steve N -----Original Message----- From: Malcolm [mailto:[email protected]] Sent: Monday, December 07, 2009 8:18 PM To: [email protected] Subject: Re: CS>Food for Thought Wow! Very nice indeed Steve; Thank you! And just as a confusion factor, what do you suppose they (you know, "them") mean by: "elemental silver, even its so-called "nano-crystalline" state"? Possibly Tetra-silver (so-called?), or possibly finely divided - as in precipitated metallic Ag? - didn't the Russians experiment with that? "As confirmed experimentally, only samples containing silver compounds can deliberate silver ions in the tested media and exhibit antimicrobial activity both in vitro and in vivo." Again; Huh?? I'd think there was enough electrochemical activity in a significant wound to provoke some ionic transport; wasn't that part of what Dr. R. O. Becker investigated, and what he developed in his work with Argentum Medical; i.e. the Silverlon bandages? I wish he'd been given the credit so richly due him for his work with silver as well as with electromedicine, deep wound and bone multiple infection control, tissue regeneration, and recalcitrant (umm,) bone fracture healing. Oh well, at least they're beginning to catch up to him. On Mon, 2009-12-07 at 18:18 -0600, Norton, Steve wrote: > Here is some information that I thought the group might be interested > in. > > http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=ECSTF8000011000021000001000001&idtype=cvips&gifs=yes > > Treatment of Various Surfaces with Silver and its Compounds for > Topical Wound Dressings, Catheter and Other Biomedical Applications > > “The applications of surfaces treated with silver and its compounds > include devices used as topical wound dressings, urinary catheters, > endotracheal tubes, cardiac valves etc. Treatment of surfaces e.g. > textile, polymers or metals with silver or its compounds is carried > out to achieve the antimicrobial action of silver ions. Several > approaches of surface treatment of medical devices for the > antimicrobial purposes, such as electrodeposition, electroless > deposition, physical vapor deposition, Picture (Device Independent > Bitmap)- radiation, etc. have been used in practice. It is clear that > only silver ions are responsible for the antimicrobial activity. As > confirmed experimentally, only samples containing silver compounds can > deliberate silver ions in the tested media and exhibit antimicrobial > activity both in vitro and in vivo. There is no evidence that > elemental silver, even its so-called "nano-crystalline" state, > exhibits an antimicrobial activity. Consequently, the devices coated > with "nano-crystalline" silver should carefully be taken into > consideration before the application.” > > Full article in google books: > > http://books.google.com/books?id=mWFylRiXV8cC&pg=PT9&lpg=PT9&dq=% > 22Treatment+of+various+surfaces+with+silver+and+its+compounds+for > +topical+wound+dressings% > 22&source=bl&ots=ixGCz2qti9&sig=of-Mkcn3VyMVbo0syg6hZMiY788&hl=en&ei=-pMdS7rvN87anAfX2dzeAw&sa=X&oi=book_result&ct=result&resnum=2&ved=0CBIQ6AEwAQ#v=onepage&q=%22Treatment%20of%20various%20surfaces%20with%20silver%20and%20its%20compounds%20for%20topical%20wound%20dressings%22&f=false > > “Based on the observation that metallic silver may exhibit some > antimicrobial activity, when sufficiently long in contact with > interstitial fluids, and considering the fact that only silver ions, > and not silver metal, are responsible for the antimicrobial activity. > One can conclude that electrochemical or corrosion phenomena plays a > significant role in the antimicrobial activity of pure silver.” > > > Some more food for thought. > > http://www.ncbi.nlm.nih.gov/pmc/articles/PMC127333/ > > Chemiosmotic Mechanism of Antimicrobial Activity of Ag+ in Vibrio > cholerae > > “Although the antimicrobial effects of silver salts were noticed long > ago, the molecular mechanism of the bactericidal action of Ag+ in low > concentrations has not been elucidated. Here, we show that low > concentrations of Ag+ induce a massive proton leakage through the > Vibrio cholerae membrane, which results in complete deenergization > and, with a high degree of probability, cell death.” > > > - Steve N > -- The Silver List is a moderated forum for discussing Colloidal Silver. Instructions for unsubscribing are posted at: http://silverlist.org To post, address your message to: [email protected] Address Off-Topic messages to: [email protected] The Silver List and Off Topic List archives are currently down... List maintainer: Mike Devour <[email protected]>
