Experts: It’s the Silver Ion That Gives Colloidal Silver Its Antimicrobial Power…
You’ll find some people on the internet claiming that the ionic form of colloidal silver doesn’t work.
But ionic silver is the #1 most popular form of colloidal silver in the world today because, simply stated it’s the most effective form.
Here’s what the experts have to say about the powerful infection-fighting qualities of ionic silver:
“The antimicrobial properties of silver are due to the silver ion…”
– Romans, I.B. 1954. Oligodynamic metals. In Antiseptics, Disinfectants, Fungicides, and Chemical and Physical Sterilization. Philadelphia, Lea & Febiger, 388-428.
“Silver ions are bactericidal, antifungal, protozoicidal, and active against herpes simplex virus.”
– Russell, A.D., et al. 1994. Antimicrobial activity and action of silver. Progress in Medicinal Chemistry, 31, 351-370.
“…the microbicidal activity of silver is significantly ion influenced.”
– Simonetti, N., et al. 1992. Electrochemical Ag+ for preservative use. Applied and Environmental Microbiology, 58(12), 3834-3836.
“To be bactericidal, the silver must be available as a solution, and the efficacy of the solution is dependent on the concentration of silver ions present in the solution…silver is effective against a broad range of antibiotic-resistant organisms, which is expected because silver has been regularly found to be effective against antibiotic-resistant organisms”.
– Wright, J. Barry, Lam, Kan, and Burrell, Robert E. 1998. Wound management in an era of increasing bacterial antibiotic resistance: a role for topical silver treatment. American Journal of Infection Control, 26(6), 572-577.
“Beginning in 1973, in vitro studies demonstrated that such ions were an effective antibiotic with a very broad spectrum and favorable quantitative evaluations compared with synthetic antibiotics…The failure of other nontoxic metal ions to produce a similar alteration with the same electrical parameters strongly indicates that the electrically generated silver ion is the agent responsible for the observed cellular changes…Healing rates in these wounds are significantly accelerated and are accompanied by enhanced healing of the bone, soft tissue, nerve, and skin, with replacement of missing tissues by histologically normal tissues…The responsible agent for these cellular effects is believed to be the electrically generated silver ion”.
– Becker, Robert O. 2000. Effects of electrically generated silver ions on human cells and wound healing. Electro- and Magnetobiology, 19(1), 1-19.)
“Silver ions were more effective at inhibiting bacteria than platinum, gold, copper and stainless steel ions.”
– Spadaro, J.A., et al. 1974. Antibacterial effects of silver electrodes with weak direct current. Antimicrobial Agents and Chemotherapy, 6(5), 637-642.)
“The Ag+ filler showed significantly more antibacterial activity than the control filler without silver ions…The findings indicate that the antibacterial effect is due to silver ions released from the Ag+-containing filler.” (Yamamoto, Kohji, et al. 1996. Antibacterial activity of silver ions implanted in silicone dioxide filler on oral Streptococci.
– Dental Materials, 12: 227-229.
“It has been shown shown that the ionic portion of a colloidal silver protein is the germicidal component.”
– Sollman, Torald, and J.D. Pilcher 1924. Organic, protein and colloid silver compounds: Does the “colloidal silver” become available as antiseptic? Journal of Laboratory and Clinical Medicine. 10:38-42.
“…the bactericidal power of CS (colloidal silver) is due to the silver ion.”
– Uegaki, Shingo. 1930. Influence of the blood constituents on the bactericidal power of colloidal silver. Japanese Journal of Experimental Medicine. 8: 573-613.)
“Silver is a disinfectant for non-spore forming bacteria at concentrations about 1000 times lower than the levels at which it is toxic to mammalian life. …The ionic form of silver is necessary.”
– British Columbia Ministry of Environment, Ambient Water Quality Criteria for Silver, Environmental Protection Department, February 19, 1996
“In the present paper we show that silver ions inhibit the respiratory chain of E. coli. The most sensitive site of inhibition was between the bcytochromes and cytochrome a,. A further site of inhibition was located between the site of substrate interaction with the respiratory chain and flavoprotein.”
– “The Effect of Silver Ions on the Respiratory Chain of Escherichia coli,” P. D. Bragg and J. D. Rainnie, Department of Biochemistry, University of British Columbia
“…conversion of silver to silver ions is necessary for efficacy.”
– Albert T. McManus, MD, Chief of Microbiology, Brooke Army Medical Center, Fort Sam Houston, Texas, Army Burn Center, United States Army Institute of Surgical Research
“Ionic silver, although technically a colloidal, does seem to offer more beneficial properties than the traditional colloidal silver. Ionic silver can be generated by electrolyzing the silver metal or dissolving silver compounds and appears to have superior antimicrobial activity.
One of the reasons for this, in addition to the charge of the particles, might be that ‘silver ions in solution offer a greater surface area because of the fact that they are individual atoms, not clusters of atoms as seen in a colloid.’ This means that ‘they react more quickly and readily,’ and since they ‘are relatively smaller than colloidal particles, they will penetrate…more rapidly and effectively.’”
… The term oligodynamic only applies to “charged silver particles,” or ions (Ag+). Neutral silver (Ag) does not have the microcidal nature that silver does in the ionic state. The charge of the ion is necessary in facilitating electron displacement in microbes. It is the charge that “effectively yanks electrons away from a molecule…weakening the molecular bond and rendering it susceptible.”
In his retrospective study of silver, published in the Journal of Nutritional & Environmental Medicine, Eric Rentz indicates that microbial cells “selectively bond only with Ag+ [i.e., ionic silver – ED]”…
… the safety of oligodynamic silver (Ag+) is firmly established: it “is not…toxic to the immune, cardiovascular, nervous, or reproductive systems [and it] is not considered to be carcinogenic.”
On the contrary, Ag+ [i.e., ionic silver – ED] manifests all of the therapeutic benefits that have been historically established for silver. The toxicities noted above are directly connected with silver products that contain “reduced or neutral silver [which] has no known medical value.” These include silver salts, silver compounds, and colloidals that are created without ions…
…These products will still provide some benefit if there are silver ions present, but most of them “have difficulty achieving biologically meaningful concentrations of Ag+”…
…The importance of this must not be overlooked. The fears expressed by the FDA concerning the toxic effects of silver can only apply to those products that contain non-oligodynamic forms of silver, not those that are ionic (Ag+).”
– S.M. Foran, Therapeutic Properties of Silver: an Historical and Technical Review
“Silver compounds have a wide variety of uses as caustics, astringents, antiseptics, and germicides. Their activity resides in the silver ion, which is a protein precipitant [in that] it is toxic to bacteria by precipitating the protein in the bacteria protoplasm.”
– Handbook of the Hospital Corps of the United States Navy, 1953
“All silver-based antimicrobials act against bacteria through the action of silver ions (Ag+). The effect of silver ions against microorganisms is well established and is referred to as the oligodynamic effect. Silver ions interact with bacteria cells through 3 mechanisms:
- Damage cell membrane
- Displace Ca2+ and Zn2+ ions
- Interact with sulphur, oxygen or nitrogen
Silver ions are active against a broad range of gram-positive and gram-negative bacteria. Unique qualities of silver ions are: Low risk for bacteria resistance, effective in very low concentrations, no human toxicity”
– Dr. Murray J. Height, Ph.D, Chief Technology Officer, HeiQ Materials, Silver Nanotechnology Working Group
“It is the silver ion (Ag+) that provides silver with its unique recognition as the healthful metal. Its bactericidal activity is unique because though this ion breeches walls of bacterial cells, it does not do so to mammalian cells. This selectivity, which remains unclear, was perceived during ancient times leading to its universal use.”
– Samuel F. Etris, The Silver Institute, writing in Silver Compounds
“It has been suggested that the number of pathogens killed relates directly to the number of silver ions present…The research data confirmed that it is not the total amount of silver in suspension, but the total amount of ionized silver in solution, that determines effectiveness.”
– Environmental Health Foundation, Silver for Human Health
“…the principle activity of silver is as a result of the production of silver ions within an aqueous matrix… Silver ions interact with a number of components of both bacterial, protozoal and fungal cells. Toxicity to microbial cells is exhibited at very low concentrations…”
– Technical White Paper: Antimicrobial Activity of Silver, Industrial Biological Services, Ltd.
“Silver compounds are employed for their antiseptic and germicidal action on bacteria. The effectiveness of such preparations is due largely to the free silver ions. The higher the concentration of free ions the greater will be the germicidal effect.”
– Germicidal Efficiency of Some Silver Compounds Tested by the Improved Tissue-Culture Method, D.C. Foord, W.A. McOmie and A.J. Salle, May 1938 vol. 38 no. 4 572-574, Experimental Biology and Medicine
“The germicidal action of a specified amount of silver was found to be related to the concentration of silver ions rather than to the physical nature of the silver from which the ions were originally derived”.
– Chambers, Cecil W., Proctor, Charles M., and Kabler, Paul W. 1962. Bactericidal effect of low concentrations of silver. Journal of the American Water Works Association, 208-216.
“Silver can exist in ‘elemental’ or ‘ionic’ form. Silver ions are also referred to as ‘Ag+’ or ‘silver cations’. All silver-containing products, whether elemental or ionic, achieve their antimicrobial effect via the action of silver cations (i.e., silver ions).”
– Systagenix Wound Management 2011, January 2011 Edition, Silver White Paper, Everything You Ever Wanted to Know About the Use of Silver in Wound Therapy, Sharon Lindsay, Systagenix
“Silver’s exact antimicrobial mechanism is unknown. It has been determined yet, however, that the free silver ion is the active agent, with evidence that silver’s antibacterial activity is directly proportional to the amount of silver ions released.”
– Proceedings of the International MultiConference of Engineers and Computer Scientists 2008, Vol II, IMECS 2008, 19-21 March 2008, Hong Kong, Electrolysis of Nano-Silver Suspension Into Ionic Form Via Membrane Electro-Osmosis Process
“The antimicrobial action of silver or silver compounds is proportional to the bioactive silver ion (Ag(+)) released and its availability to interact with bacterial or fungal cell membranes. Silver metal and inorganic silver compounds ionize in the presence of water, body fluids or tissue exudates.
The silver ion is biologically active and readily interacts with proteins, amino acid residues, free anions and receptors on mammalian and eukaryotic cell membranes.
– Silver In Health Care: Antimicrobial Effects And Safety In Use, Current Problems in Dermatology, 2006;33:17-34.
“In order for silver to have any antimicrobial properties, it must be in its ionized form (Lok et al., 2007; Rai et al., 2009). Silver in its non-ionized form is inert (Guggenbichler et al., 1999), but contact with moisture leads to the release of silver ions (Radheshkumar and Munstedt, 2005). Thus, all forms of silver or silver containing compounds with observed antimicrobial properties are in one way or another sources of silver ions (Ag+); these silver ions may be incorporated into the substance and released slowly with time as with silver sulfadiazine, or the silver ions can come from ionizing the surface of a solid piece of silver as with silver nanoparticles.”
– Microbe Wiki, Silver As An Antimicrobial Agent
“The antimicrobial affect of SDS-CS [Spark Discharge System Colloidal Silver] on Staphylococcus aureus was studied. The results show that CS solutions with an ionic silver concentration of 30 ppm or higher are strong enough to destroy S. aureus. In addition, it was found that a solution’s antimicrobial potency is directly related to its level of silver ion concentration.”
– Medical Engineering and Physics, 2008, Oct; 30(8):948-52, Colloidal silver fabrication using spark discharge system and its antimicrobial effect on Stapylococcus aureus
“Scientists have long known that silver ions, which flow from nanoparticles when oxidized, are deadly to bacteria.
But scientists have also suspected silver nanoparticles themselves may be toxic to bacteria, particularly the smallest of them at about 3 nanometers.
Not so, according to the Rice team that reported its results this month in the American Chemical Society journal Nano Letters.
In fact, when the possibility of ionization is taken away from silver, the nanoparticles are practically benign in the presence of microbes, said Pedro Alvarez, George R. Brown Professor and chair of Rice’s Civil and Environmental Engineering Department.”
— Rice University News, “Ions, Not Particles, Make Silver Toxic to Bacteria”
“Metallic silver is inert in the presence of human tissues but ionizes in the presence of moisture, body fluids, and secretions to release the biologically active Ag+ (i.e., ionic silver)”.
– Alan B.G. Lansdown, A Pharmacological and Toxicological Profile of Silver as an Antimicrobial Agent in Medical Devices, Advances in Pharmacological Sciences, Vol. 2010, Article ID 910686
“Silver is also either ionic (it carries a positive electrical charge) or non-ionic (has no electrical charge). In order for silver to be biocidal – meaning it can interact with bacterial cell tissues and reduce harmful microorganisms in a wound – it must be in an ionic form. Ionic forms of silver are indicated by plus signs (+), meaning the form contains a positive charge.”
– A Closer Look at Silver, Exciton Technologies, Inc.; Heather L. Orsted, RN, BN, ET, MSc; Carla Spina, PhD Chem.; Edie Attrell, RN, BN, ET, IIWCC; Chester Ho, MD; Lindsay Kalan, PhD and David H. Keast, BSc, MSc, Dip Ed, MD, CCFP, FCFP
“…an inert lump of silver isn’t going to do much. To be effective, it must first ionize. Research has shown that it’s silver in its ionic (Ag+) and notelemental form that is antibacterial.
An atom of silver has a neutral charge; we need to ionize it – take away a negatively charged electron – to transform it into its positively charged ionic form. Silver-based antibacterial surfaces must release silver ions directly into the pathogenic environment to be effective.”
– Rohan Shirwaiker, Assistant Professor of Industrial and Systems Engineering at North Carolina State University, Silver Shines as Antibacterial for Medical Implants
“In metallic (elemental) form, silver is unreactive and cannot kill bacteria. To become bactericidal, silver atoms (denoted as Ag or Ag0) must lose an electron and become positively charged silver ions (Ag+ ).
Elemental silver ionises in air, but ionises more readily when exposed to an aqueous environment such as wound exudates.
…Silver ions are highly reactive and affect multiple sites within bacterial cells, ultimately causing bacterial cell death. They bind to bacterial cell membranes, causing disruption of the bacterial cell wall and cell leakage.
Silver ions transported into the cell disrupt cell function by binding to proteins and interfering with energy production, enzyme function and cell replication.
Silver ions are active against a broad range of bacteria, fungi and viruses, including many antibiotic-resistant bacteria, such as meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE).”
– Wounds International Expert Working Group, 2012, (a working group featuring 12 experts from the fields of medicine, wound healing, geriatric care, hospital care, pharmaceutical sciences, trauma surgery, burn care, infection control and nursing)
“There is an ongoing debate over whether silver nanoparticles inherently possess toxicity, or if microbial toxicity is dependent on leached Ag+ ions from nanoparticles.
To clarify this issue, we utilized XANES/EXAFS analysis to assess the fine structure of silver particles present within Bacillus subtilis cells treated with 100 ppm of silver nanoparticles.
This data strongly suggests that in aqueous solutions, silver nanoparticles leach off positively charged silver ions, which subsequently enter bacterial cells and are oxidized to form Ag2O [silver chloride – ED].
If silver nanoparticles entered cells directly, it would have been possible to detect spectra corresponding to the Ag standard.
To the best of our understanding, this is the first study to directly analyze silver particles present within bacterial cells treated with silver nanoparticles, and the results indicate that positively charged silver ions are primarily responsible for silver nanoparticle microbial toxicity.
…our results support the theory that silver nanoparticles exert microbial toxicity through the release of positively charged silver ions that subsequently penetrate into bacterial cells.”
– The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis are Mediated by Released Ag+ Ions, PLOS-One, December 15, 2015
“The antibacterial form of silver is the ions. Minute sub-particles [of metallic nanosilver – ED] continuously emit a sufficient number of positively charged ions. These destroy the enzymes of the bacteria, destabilize the cell membrane, the cell plasma or the cell wall and prevent their reproduction. The bacteria do not survive this concentrated attack.”
— International Food Resource Journal in 2011, “A study on the minimum inhibitory concentration and minimum bactericidal concentration of Nano Colloidal Silver on food-borne pathogens”
“This study aimed to investigate the effectiveness of silver in ionic and nano [i.e., metallic – ED] form as antimicrobial toward a panel of L. monocytogenes isolates…The relation between the sensitivity assay and the amount of ions at the tested time points, in both cases (AgNPs and AgNO3) suggests that ions are the more effective elements exerting antibacterial activity … Our study suggests that L. monocytogenes is sensitive to silver and that the efficacy is linked to ionic release.”
– Frontiers in Microbiology, March 7, 2016, “Silver as Antibacterial Toward Listeria monocytogenes”
“Given the very limited gastrointestinal absorption of metallic nanoparticles of similar size in other studies in rodents, we assert that most silver detected in patient blood samples is ionic, with no evidence that intact silver nanoparticles are either absorbed into circulation through the human digestive tract, or attached to blood components (e.g., proteins, platelets and cells).”
– Nanomedicine: Nanotechnology, Biology, and Medicine, October 2014, “In vivo human time-exposure study of orally dosed commercial silver nanoparticles”
[All quotes were taken from the Experts Quotes page or the Clinical Studies page at The Silver Edge web site.]
Silver Ions Rule!
The bottom line is that silver ions flat out rule.
That’s not to say other forms of colloidal silver – such as particulate, or metallic silver, or silver proteins, or silver citrate, etc. – are ineffective. They aren’t.
But they are only effective to the extent that they release silver ions in the system. The more silver ions they release, the more effective they are.
So the next time someone tries to tell you ionic silver is “ineffective,” show them this article and watch ‘em squirm.
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