Colloidal Silver clinical studies and reports


Clinical Studies and Reports on the
Antimicrobial Qualities of Colloidal Silver








The following PDF documents consist of a variety of clinical studies and independent research reports on the antimicrobial qualities of colloidal silver-related products including silver ions, silver compounds, silver nanoparticles, nanosilver compounds, silver-impregnated and silver-coated products, and many other forms of silver being used in a wide variety of ways, but almost all for the purpose of benefitting from the powerful antimicrobial qualities of silver itself.

These studies and reports are supplied for informational purposes only, and should not be construed in any way as providing medical advice or guidance. They cover a wide range of data on silver, including some surprising findings and discoveries regarding silver’s powerful antimicrobial, infection-fighting and disinfectant qualities.

These studies and reports are compiled here with the intent of giving the reader or researcher a general understanding of the many uses of antimicrobial silver, from a variety of viewpoints, both clinical and personal. The studies are not meant to convey efficacy of any particular colloidal silver product.

Because research into antimicrobial silver is ongoing, and because opinions and conclusions tend to vary depending upon the factors involved in different studies, these studies and reports should be considered merely as a starting point for your own research, and not be considered the final word on silver and its many antimicrobial, infection-fighting or disinfectant benefits.

Note to Publishers and Authors: If you feel any of these PDF files are on this site in violation of copyright, please inform me immediately by email, at, or at the phone number at the bottom of this page. These PDF files have been garnered from a variety of internet sources where they were found posted with no restrictions. They are here under fair use, and for non-commercial informational purposes only.

Note to Readers: The following files are PDF files. This means you need a program called Adobe Acrobat on your computer, in order to open and view them. Most computers come pre-installed with Adobe Acrobat. But yours may not. If that’s the case, you can download Adobe Acrobat at no cost from Readers should also take note that downloading, emailing, posting or any other re-publication of these files in other forums may constitute a violation of the author’s copyright.

120 Years of Nanosilver History Demonstrate Its Safety and Repudiate Attempts to Paint It As a “New Substance” With “Unknown Risks”
Nanosilver is assumed to be a new material because of the relatively recent emergence of the term “nano”. However, on close inspection nanosilver materials have a long, 120-year history of relatively safe and regulated use, chiefly in the form of colloidal silver. Historical perspective demonstrates that nanosilver has been intentionally manufactured and adopted commercially across a wide spectrum of everyday applications for many decades. To declare nanosilver materials as “new chemicals” with “unknown properties” that are “potentially harmful” simply on the basis of a change in nomenclature to the term “nano,” and ignoring the accumulated knowledge of its scientific and regulatory heritage demonstrating both safety and efficacy in a wide range of applications, would be a mistake that does not serve the public interest.
First Ever Double-Blind Human Ingestion Study on Nanosilver
American Biotech Labs has just released what is believed to be the first ever human ingestion safety study on a colloidal silver supplement. The published abstract for the study states that ingestion of the patented ABL nanosilver particle showed no negative effects on any tested system in the body. The study included 3, 7 and 14-day exposures to American Biotech Labs 10 ppm (15 ml/day) silver solution in a double-blind, placebo controlled cross-over phase design. Healthy volunteer subjects (36 subjects in all, 12 per each time-exposure studied), underwent complete metabolic, blood and platelet count, urinalysis tests, sputum hyper-responsiveness and inflammation evaluation, physical examinations, vital sign measurements, and magnetic resonance imaging of the chest and abdomen at baseline and at the end of each phase. According to the study authors, “No clinically important changes in any metabolic, hematologic, or urinalysis measure identified were determined. No morphological (or structural) changes were detected in the lungs, heart (cardiac function) or abdominal organs. No changes were noted in sputum reactive oxygen species or in pro-inflammatory cytokines.”
Ionic Silver Safety: An In Vitro Toxicity Study of a Colloid Silver Health Product and Atomic Quantum Clusters of Silver and Gold (Ionosil Study)
Is colloidal silver toxic to cells? In this in vitro clinical study conducted in June 2007 at The Faculty of Pharmaceutical Sciences, Copenhagen University, the researcher set out to discover if Ionosil (i.e., Sweden’s leading brand of ionic colloidal silver) is toxic to cells, using human alveolar lung epithelial cell line A549. The researcher compared the effects of Ionosil to atomic gold and silver quantum clusters on the cells, looking for cytotoxicity (i.e. cell damage), inflammation and DNA damage. No toxicity, DNA damage or inflammation was found from the ionic colloidal silver solution.
Nanoparticle Colloidal Silver Demonstrated Safe For Humans
This company got tired of the falsehoods and misconceptions being promulgated by against colloidal nanosilver by environmentalists, and has set the record straight!
Safety Information Related to Nanoscalar-Oligodynamic Silver Ions
Another company sets the record straight regarding the safety of nano-sized ionic colloidal silver!
An Evaluation of Acute Toxicity of Colloidal Silver Nanoparticles
Researchers tested mice for acute oral toxicity, eye irritation, corrosion and dermal toxicity of colloidal silver nanoparticles (AgNPs) following OECD guidelines. Oral administration of AgNPs at a limited dose of 5,000 mg/kg produced neither mortality nor acute toxic signs throughout the observation period. Percentage of body weight gain of the mice showed no significant difference between control and treatment groups. In the hematological analysis, there was no significant difference between mice treated with AgNPs and controls. Blood chemistry analysis also showed no differences in any of the parameter examined. There was neither any gross lesion nor histopathological change observed in various organs. The results indicated that the LD50 of colloidal AgNPs is greater than 5,000 mg/kg body weight. In acute eye irritation and corrosion study, no mortality and toxic signs were observed when various doses of colloidal AgNPs were instilled in guinea pig eyes during 72 hr observation period. However, the instillation of AgNPs at 5,000 ppm produced transient eye irritation during early 24 hr observation time. No any gross abnormality was noted in the skins of the guinea pigs exposed to various doses of colloidal AgNPs. In addition, no significant AgNPs exposure relating to dermal tissue changes was observed microscopically. In summary, these findings suggest that colloidal AgNPs could be relatively safe when administered to oral, eye and skin of the animal models for short periods of time.
Genotoxicity, Acute Oral and Dermal Toxicity, Eye and Dermal Irritation and Corrosion, and Skin Sensitization Evaluation of Silver Nanoparticles
This is an abstract of a 2012 study published in the journal Nanotoxicology, in which researchers tested silver nanoparticles for genotoxicity, acute oral and dermal toxicity, eye and dermal irritation and corrosion, and skin sensitization. In the bacterial and animal tests performed, the researchers found that silver nanoparticles, at fairly high dosage levels, do not induce genotoxicity or abnormal signs of mortality. There was no oral or dermal toxicity. There was no acute eye or dermal irritation of corrosion, and extremely low skin sensitization. Some cytotoxicity (cell toxicity) was observed in the bacterial tests, which is to be expected since silver is a known bacteriocide. One test animal out of 20 showed low level signs of erythema (i.e., superficial reddening of the skin), prompting researchers to classify the silver nanoparticles used as “a weak skin sensitizer.”
The Altman Study: Colloidal Silver, Where Does It Go When You Drink It? How Long Does It Stay There?
The classic 1990’s study demonstrating the body’s ability to effectively excrete silver.
Safety and Efficacy of Intravenous Oligodynamic Silver
Dr. Kent Holtorf, M.D. discusses historical safety and efficacy of various forms of colloidal silver, used orally and intravenously, including oligodynamic silver. [*Web editor’s note: Never use colloidal silver intravenously except under a doctor’s direction and supervision. Some deaths attributed to the use of intravenous colloidal silver have been recorded in early medical literature. Additionally, colloidal silver for intravenous use must be prepared as an isotonic solution to avoid the lysing of red blood cells.]
Silver Nanoparticles Interactions with the Immune System: Implications for Health and Disease
In this study overview of the way silver nanoparticles interact with the immune system, researchers found that silver nanoparticles strongly inhibited cytokine production, and did not show pro-inflammatory effects. According to the study authors, “It has been shown in vivo that silver NPs act to decrease inflammation through cytokine modulation.” The implication being that silver nanoparticles may one day play a key role in decreasing inflammation in inflammatory medical conditions. The study overview also found that topical application of silver nanoparticles promotes wound healing.
Evaluation of Hazard and Exposure Associated with Nanosilver and Other Nanometal Oxide Pesticide Products
The Silver Nanotechnology Working Group demonstrates the history and safety of commercial products containing silver nanoparticles.
Silver Nanoparticles: No Threat to the Environment
Dr. George J. Maass demolishes the idea that silver nanoparticles pose a threat to the environment.
Assessment of Nanosilver In Textiles On the Danish Market: No Likely Risk to Environment or Humans
In a six-month study (Sept. 2011 to March 2012) funded by the Danish Environmental Protection Agency, carried out by the Danish Technological Institute and published by the Danish Ministry of the Environment, it was found that nanosilver in textiles including various forms of clothing as well as cleaning cloths and children’s toys pose “no risk of health effects or environmental effects.” Indeed, regarding the potential for harm to the environment, the study authors unequivocally state, “…the scenario for environmental exposure through discharge of sewage effluent is not likely to pose a risk of biological effects in the aquatic environment arising from the use of nanosilver in textiles…” And regarding human exposure, the researchers further state, “The calculated risk ratios relevant for the three selected human exposure scenarios indicate that the risk from each individual scenario is very low. Also combined exposures from different sources with similar migration patterns are not likely to pose an unacceptable risk to consumers based on the findings in this study.”
Federal Register: Residues of Silver in Foods from Food Contact Surface Sanitizing Solutions; Exemption from the Requirement of a Tolerance
Spray silver disinfectant products are ruled safe for use on food contact surfaces by EPA.
History of the Medical Use of Silver
Silver has been used for at least six millennia to prevent microbial infections, and was the most important antimicrobial agent available before the introduction of antibiotics.
The Long History of Silver in Health and Healing
The germicidal properties of silver, although not recognized as such, have been utilized since the times of the ancient Mediterranean and Asiatic cultures.
Science Digest’s 1978 Article on Silver and Healing by Jim Powell
This is the famous, oft-quoted 1978 Science Digest article on silver and healing, by Jim Powell, in its entirety.
Activity of Colloidal Silver Preparations Towards Smallpox Virus
Colloidal silver demonstrated to be effective against smallpox virus.
Characterization of Antiplatelet Properties of Silver Nanoparticles
Silver nanoparticles prevent blood from clotting in animal model and in vitro.
Antitumor Activity of Colloidal Silver on MCF-7 Human Breast Cancer Cells
Will colloidal silver be the first big cure for breast cancer?
Toxicity of Nanosilver on Osteoblast Cancerous Cell Line
According to the authors of this study, published in the journal International Nano Letters (January 2011), nanosilver exhibited “broad spectrum inhibition” against the cancer cell line studied. The authors state, “Many attempts have been made to use silver nanoparticles as an anti-cancer agent and they have all turned up positive…The purpose of this study was to assess the biological assay of nanosilver (Nanocid®) on osteoblast (G292) cancerous cell line. The effect of nanosilver on these cells was evaluated by light microscopy, and by cell proliferation and standard cytotoxicity assays. The results demonstrate a concentration-dependent toxicity for the cell tested, and IC50 was determined 3.42 µg/mL, suggest(ing) that the product is more toxic to cancerous cells compared to other heavy metal ions.” The authors concluded, “In general, silver nanoparticles should serve as one of the best ways of treating diseases that involve cell proliferation and cell death.”
Antitumor Activity Of Silver Nanoparticles In Dalton’s Lymphoma Ascites Tumor Model
Study confirms the antitumor properties of silver nanoparticles, and suggest that they may be a cost-effective alternative in the treatment of cancer.
Viral Pathogens and Severe Acute Respiratory Syndrome: Oligodynamic Ag1 for Direct Immune Intervention
Retrospective study of silver-based therapeutics briefly reviews their history, and explores the modern application of charged silver particles as an antiviral agent.
A Mechanistic Study of the Antibacterial Effects of Silver Ions on Escherichia coli and Staphylococcus aureus
Researchers discover one of the ways silver ions destroy pathogens, i.e., by attaching to DNA and preventing the pathogen from replicating.
Effects of Electrically Generated Silver Ions on Human Cells and Wound Healing
Dr. Robert O. Becker’s classic study on healing wounds with electrically generated silver ions.
Antibacterial Activity and Mechanism of Action of the Silver Ion in Staphylococcus aureus and Escherichia coli
Electrically generated silver ions used in washing machines are shown to cause significant reductions in bacterial counts of Staph aureus and E. coli.
NASA Document on Silver Ionization Process for Water Purification on Manned Space Flights
Silver plays a key role in assuring safe water for manned space crews.
Silver News, 1st Quarter 2010, Nanosilver Overcomes Blood Platelet Disorders
Blood platelet aggregation is serious and can be life threatening; nanosilver may act as an effective anticoagulant.
Antibacterial Efficacy Studies of Silver Nanoparticles Against Escherichia coli ATCC-15224
Silver nanoparticles are shown to dramatically reduce E. coli bacterial counts.
Anti-bacterial Performance of Colloidal Silver-treated Laminate Wood Flooring
Colloidal silver-treated laminate wood flooring keeps the bacteria away.
Silver-Coated Nylon Fiber as an Antibacterial Agent
Silver-coated nylon fabric prevents infections in wounds.
Silver-Nylon: a New Antimicrobial Agent
Silver-coated nylon fabric prevents infections in wounds.
Bob Beck: Take Back Your Power
Dr. Bob Beck’s classic treatise on healing with electromedical devices and colloidal silver.
Bactericidal Activity of Combinations of Silver–Water Dispersion™ with 19 Antibiotics Against Seven Microbial Strains
The famous BYU study demonstrating the ability of a colloidal silver solution to boost the effectiveness of antibiotic drugs against drug-resistant microbes.
Antifungal Textiles Formed Using Silver Deposition in Supercritical Carbon Dioxide
Supercritical CO2 processing can be used to infuse textiles used in hospitals with silver nanoparticles, giving them profound antifungal properties.
Bactericidal Effect of Silver Nanoparticles Against Multidrug-resistant Bacteria
Silver nanoparticles shown to be effective broad-spectrum biocides against a variety of drug-resistant bacteria.
In Vitro Evaluation of the Activity of Colloidal Silver Concentrate Against Pseudomonas aeruginosa Isolated from Postoperative Wound Infection
Colloidal silver proven effective against multi-drug resistant Pseudomonas aeruginosa, one of the most deadly drug-resistant pathogens.
Colloidal Silver As a New Antimicrobial Agent
Colloidal silver was found to be effective against drug-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aregnosa and Salmonells typhi.
Colloidal Silver for Lung Disease in Cystic Fibrosis
An 11-year old Cystic Fibrosis victim with multi-drug resistant Burkholderia multivorans and Stenotrophomonas maltophilia responds to colloidal silver.
Ultrastructural Localization and Chemical Binding of Silver Ions in Human Organotypic Skin Cultures
The human body is demonstrated to have a specific method of neutralizing the potentially toxic in vitro effects of silver ions on human cells, utilizing the antioxidant glutathione.
Patent for Antiviral Colloidal Silver Composition
“We disclose a colorless composition comprising silver particles and water [manifesting] significant antimicrobial properties including antiviral properties.”
MTR Uses Silver Nano Technology to Enhance Hygiene Levels on Passenger Rail Lines
Japanese public railway line uses silver nanotechnology to keep contact surfaces free of pathogens
Induced Dedifferentiation: A Possible Alternative to Embryonic Stem Cell Transplants
Famous Robert O. Becker study demonstrating how electrically generated silver ions can produce tissue regeneration at wound site, or even limb regeneration, thus providing a potential morally acceptable alternative to embyronic stem cell transplants.
Therapeutic Properties of Silver: A Historical and Technical Review, by S.M. Foran
Even now, with over one hundred antibiotics available, there is a fear that many bacteria will become resistant to all antibiotics, plunging humanity back into the conditions that existed in the pre-antibiotic age. This study reviews the historical usage of silver and concludes that oligiodynamic silver in the form of silver ions may well be the answer to this most pressing of medical problems.
The Effect Of Silver Ions On The Respiratory Chain Of Escherichia Coli
Researchers demonstrate that silver ions inhibit the respiratory chain of E.coli, killing the pathogen.
Promising Cure for URTI Pandemics, Including H5N1 and SARS: Has the Final Solution to the Coming Plagues Been Discovered? (Part II), by Eric Gordon, MD and Kent Holtorf, MD
Drs Eric Gordon, MD and Kent Holtorf, MD make their case that oligodynamic silver hydrosol is the safe, natural solution to SARS and other potentially deadly viral pandemics.
Nanotechnology’s Latest Oncolytic Agent: Silver, Cancer & Infection Associations (Part III) By John Apsley, DC, Kent Holtorf, MD, Eric Gordon, MD, Wayne Anderson, ND, and Rashid Buttar, DO
Landmark studies over the past several decades have demonstrated that oligodynamic Ag+ could play a pivotal role in overcoming cancerous processes. This article reviews these findings and offers a proposal for future studies and protocol development.
Antibacterial Efficacy of Colloidal Silver Alone and in Combination With Other Antibiotics on Isolates from Wound Infections
Low dose colloidal silver kills antibiotic-resistant staph and E.coli, and does not interfere with therapeutic efficacy of prescription antibiotics tested.
Nanotechnology In Medicine And Antibacterial Effect Of Silver Nanoparticles
Silver nanoparticles demonstrated to be the answer to the increase in new resistant strains of bacteria against most potent antibiotics.
Microbial Multi-Drug Resistance (MDR) and Oligodynamic Silver
The idea of silver-resistance among pathogenic microbes is explored, and placed in proper context with actual facts in this white paper by the Immunogenic Research Foundation.
Exposure Related Health Effects of Silver and Silver Compounds — A Review
This critical review of the medical literature dating back to the early 1900’s demonstrates that it is soluble silver compounds such as silver nitrate, silver chloride, silver acetate, silver protein and others that are responsible for the vast majority of cases of skin-staining (i.e., argyria) reported in the medical literature. “Many researchers attribute the pigmentation process associated with generalized argyria solely to soluble silver compounds…”
Technical White Paper: Antimicrobial Activity of Silver (Is Largely Dependent Upon the Presence of Silver Ions)
The antibacterial activity of silver ions, metallic silver and silver nanoparticles is discussed in this Technical White Paper from Industrial Biological Services, Ltd. of Berkshire, England. The paper concludes that silver ions are the principle active antimicrobial species of silver, with metallic silver being relatively unreactive, and silver nanoparticles exhibiting size-dependent activity against both bacteria and viruses. The paper also concludes “The mechanism depends on both the concentration of silver ions present and the sensitivity of the microbial species to silver. Contact time, temperature, pH and the presence of free water all impact on both the rate and extent of antimicrobial activity. However, the spectrum of activity is very wide and the development of resistance relatively low, especially in clinical situations.”
Antifungal Properties of Electrically Generated Metallic Silver Ions
The well-known 1976 study by R.O. Becker, Berger, Spadaro, Bierman and Chapin, which demonstrated conclusively the powerful antifungal properties of electrically generated silver ions.
Colloidal Silver in Sepsis
The 1915 study published in the Transactions of the American Association of Obstetricians and Gynecologists, Vol. XXVIII, demonstrating electrically generated colloidal silver to be effective against blood-borne infections (i.e., sepsis).
Ammonia Hypothesis of Ionic Silver Utility In Vivo
This is the brilliant blow-by-blow refutation of Frank Key’s “silver chloride hypothesis” by Stuart Thomson, director of research at Gaia Research Institute. Thomson demonstrates that, contrary to Key’s assertion, hydrochloric acid in the stomach does not render ionic silver insoluble. Rather, naturally occurring ammonia in the human body — which plays an important role in health and well-being — acts as a solvent to diminish the bonding effects of hydrochloric acid on silver ions, and renders soluble again any silver bound as AgCl, both in the digestive tract and systemically. This report is excerpted from a long-running debate on The Silver List.
Everything You Ever Wanted to Know About the Use of Silver In Wound Therapy 2011
This is an impressive 2011 White Paper by Systagenix Wound Management, explaining the scientific basis for the use of silver dressings in wound management and clinical practice, and providing a general background on silver as an antimicrobial, including details on its mode of action, potential for resistance and safety profile, as well as an overview of the current available commercial silver dressings.
Silver Nanoparticles As Broad-spectrum Bactericidal and Virucidal Compounds
Another great study published in the September 2011 issue of the Journal of Nanobiotechnology, demonstrating the profound bactericidal and virucidal effectiveness of silver nanoparticles, along with implications for the use of AgNP’s against HIV and other viral pathogens.
Colloidal Silver Suspension for Treating Skin Problems in Tropical or Decorative Fish
This is a U.S. patent explaining a simple method for using colloidal silver to treat skin problems and topical infections in tropical or decorative fish, including the amounts of colloidal silver to add to the tank each day during treatment time, the level of silver that needs to be reached in the tank for maximum effectiveness, other necessary maintenance and care, as well as expected results.
Attenuation of Allergic Airway Inflammation and Hyper-responsiveness in a Murine Model of Asthma by Silver Nanoparticles
This is a groundbreaking clinical study concluding that silver nanoparticles might be effective in the prevention or treatment of asthma. According to the study authors, “Our study suggests that oxidative stress is an important determinant of allergic airway disease and that silver NPs attenuated oxidative stress in the murine asthma model. Also, by administration of silver NPs, Th2 inflammation, which is one of the main asthma-inducing immune factors, was significantly decreased. We suggest that silver NPs may be useful as a therapeutic strategy through their properties as antioxidant and anti-inflammatory agents.”
Silver Ion Water Sterilizer By Jowa
This company has installed it’s silver-based water disinfection systems on thousands of European merchant ships and cruise liners since the 1970s to help prevent bacterial contamination of the ship’s water supply. These units — operating on the same basic principle as a colloidal silver generator — have been in constant use for forty years, with the occasional replacement of the silver electrodes. Millions of people have drank the silver purified water — including crew members who drink it regularly.
Use of Silver Nanoparticles Increased Inhibition of Cell-Associated HIV-1 By Neutralizing Antibodies Developed Against HIV-1 Envelope Proteins
Another fascinating study published in the Journal of Nanobiotechnologydemonstrating that when silver nanoparticles are added to neutralizing antibodies (i.e., NABs) known to inhibit HIV-1 infection, the potency of the NABs is significantly increased, and HIV-1 transmission and infection is dramatically inhibited. The researchers are apparently working toward developing an antiviral vaginal cream that utilizes silver and NABs to help protect women from becoming infected by an HIV positive partner.
Novel Microfilaricidal (Anti-Parasite) Activity of Nanosilver
This clinical study found that nanosilver has potent anti-parasite effects against the larval stage of the parasite Brugia malayi, a roundworm which infects millions of people in India, China and throughout southeast Asia. The parasite causes a disease known as elephantitis (i.e., elephantiasis), which is characterized by intense and sometimes grotesque swelling of the legs. This may be the first time that silver has been clinically demonstrated to be effective against parasites in any stage beyond the egg stage. The researchers also found nanosilver to be safe when used against this parasite.
Silver Colloidal Nanoparticles: Antifungal Effect Against Adhered Cells and Biofilms of Candida albicans and Candida glabrata
In this important 2011 study, researchers demonstrate that “silver colloidal nanoparticles” not only have a profound antifungal effect on two forms of Candida, but is also effective in destroying the biofilms produced by these fungal pathogens. Biofilms allow pathogens to adhere to cell walls and help protect them from the immune system and any natural predators in the human body. So this is an important new study, because in many cases biofilms are what stymie modern drug-based therapies from actually getting to the pathogen. Thankfully, silver seems to have no problem busting through the biofilms.
Oral Thrush and Dental Stomatitis: Preliminary Research to Determine if Silver Nanoparticles in Mouthwash and Dentures Might Stop These Infections
In a 2012 study published in Letters in Applied Microbiology, Professor Henriques and her team looked at the use of different sizes of silver nanoparticles to determine their anti-fungal properties against Candida albicans and Candida glabrata. These two yeasts cause infections including oral thrush and dental stomatitis, a painful infection affecting around seven out of ten denture wearers. Infections like these are particularly difficult to treat because the microorganisms involved form biofilms. Professor Henriques comments: “With the emergence of Candida infections which are frequently resistant to the traditional antifungal therapies, there is an increasing need for alternative approaches. So, silver nanoparticles appear to be a new potential strategy to combat these infections. As the nanoparticles are relatively stable in liquid medium they could be developed into a mouthwash solution in the near future.”
Antifungal Effect of Silver Nanoparticles on Dermatophytes
Here’s an interesting clinical study demonstrating the effectiveness of silver nanoparticles against the pathogen most commonly responsible for toenail fungus. According to the study, “Spherical silver nanoparticles (nano-Ag) were synthesized and their antifungal effects on fungal pathogens of the skin were investigated. Nano-Ag showed potent activity against clinical isolates and ATCC strains of Trichophyton mentagrophytes and Candida species. The activity of nano-Ag was comparable to that of amphotericin B, but superior to that of fluconazole. Additionally, we investigated their effects on the dimorphism of Candida albicans. The results showed nano-Ag exerted activity on the mycelia. Thus, the present study indicates nano-Ag may have considerable antifungal activity, deserving further investigation for clinical applications.”
Mode of Antiviral Action of Silver Nanoparticles Against HIV-1
Silver nanoparticles have proven to exert antiviral activity against HIV-1 at non-cytotoxic concentrations, but the mechanism underlying their HIV-inhibitory activity has not been not fully elucidated. In this study, silver nanoparticles are evaluated to elucidate their mode of antiviral action against HIV-1 using a panel of different in vitro assays. Results: Our data suggest that silver nanoparticles exert anti-HIV activity at an early stage of viral replication, most likely as a virucidal agent or as an inhibitor of viral entry. Silver nanoparticles bind to gp120 in a manner that prevents CD4-dependent virion binding, fusion, and infectivity, acting as an effective virucidal agent against cell-free virus (laboratory strains, clinical isolates, T and M tropic strains, and resistant strains) and cell-associated virus. Besides, silver nanoparticles inhibit post-entry stages of the HIV-1 life cycle. Conclusions: These properties make them a broad-spectrum agent not prone to inducing resistance that could be used preventively against a wide variety of circulating HIV-1 strains.
Topical Delivery of Silver Nanoparticles Promotes Wound Healing
According to the study authors, “We investigated the wound-healing properties of silver nanoparticles in an animal model and found that rapid healing and improved cosmetic appearance occur in a dose-dependent manner. Furthermore, through quantitative PCR, immunohistochemistry, and proteomic studies, we showed that silver nanoparticles exert positive effects through their antimicrobial properties, reduction in wound inflammation, and modulation of fibrogenic cytokines. These results have given insight into the actions of silver and have provided a novel therapeutic direction for wound treatment in clinical practice.”
Silver Nanoparticles as Potential Antiviral Agents
From the clinical journal Molecules, a review of studies demonstrating the potent antiviral effects of silver nanoparticles against HIV-1, hepatitis B virus, herpes simplex virus, respiratory syncytial virus and monkey pox virus, and concluding that silver and other metal nanoparticles may provide opportunity to develop novel antiviral therapies with lower levels of resistance compared to conventional antiviral drugs.
Silver Nano – A Trove for Retinal Therapies
Silver nanoparticles are being discovered to have profound therapeutic properties in certain diseases of the eyes that can result in visual impairment or even irreversible blindness. This clinical study review shows that silver nanoparticles may play a successful role in reversing pathological retinal angiogenesis (neovascularization), one of the most feared complications among retinal diseases. According to the study authors, “Recent findings made by us on therapeutic applications of biologically synthesized silver nanoparticles (AgNPs) against VEGF induced retinal endothelial cells, elucidates the effectual inhibitory activities of AgNPs over the downstream signaling pathways (Src and AKT/PI3K) leading to retinal angiogenesis.” The researchers concluded that present clinical research “consequently affirms the futuristic application of silver nanoparticles as a boon to ocular therapies.”
Silver Nanoparticles Impede Biofilm Formation By Pseudomonas aeruginosa and Staphylococcus epidermidis
Pathogens that form biofilms are among the most frustrating for doctors to deal with because the protective barrier the microbes are able to erect around themselves is difficult for antibiotic drugs to penetrate. The result is often relentless and chronic infection. In this clinical study researchers found that silver nanoparticles impede the formation of the biofilm barriers normally erected by Pseudomonas aeruginosa and Staphylococcus epidermidis. According to the study authors, “Treating these organisms with silver nanoparticles resulted in more than 95% inhibition in biofilm formation. The inhibition was known to be invariable of the species tested. As a result this study demonstrates the futuristic application of silver nanoparticles in treating microbial keratitis based on its potential anti-biofilm activity.”
Venereal Diseases: Their Treatment and Cure
This is an older clinical report from the early 1900’s by Dr. Omar Wilson, M.D., and published in a journal called The Canadian Medical. Dr. Wilson discusses his success with the use of a colloidal silver protein compound known as Protargol, which he had found to be an astonishingly helpful treatment for gonorrhea when instilled into the urethra of the penis, followed by prostatic massage where appropriate. Says Dr. Wilson in his report, “Some years ago I was afforded the opportunity of experimenting with germicidal preparations in gonorrhea. After prolonged experiments I became convinced that Protargol gave the best results, and curiously enough, that one-half percent Protargol was remarkably more efficient than solutions of greater strength.”
Bactericidal Actions of a Silver Ion Solution on Escherichia coli, Studied by Energy-Filtering Transmission Electron Microscopy and Proteomic Analysis
In this study, published in November 2005 in the journal, Applied and Environmental Microbiology, researchers examined the bactericidal function of silver ions, using Escherichia coli as a model microorganism. The researchers found that the silver ion readily infiltrates the interior of E. coli, rather than residing in the cell membrane area and affecting the function of membrane-bound enzymes, as was previously theorized. According to the study authors, “The present results indicate that one of the major bactericidal actions of the silver ion is caused by its interaction with the ribosome and subsequent suppression in the expression of enzymes and proteins essential to ATP production.” In other words, the silver ions infiltrate the bacterial cell and destroy the ability of the bacteria to generate life-giving energy from the inside.
Treatment of Orthopaedic Infections with Electrically Generated Silver Ions
The famous clinical study by Dr. Robert O. Becker, M.D., and Joseph A. Spadaro, Ph.D., on healing bone non-unions and infected wounds with electrically generated silver ions. The study was published in 1978 in theJournal of Bone and Joint Surgery. The researchers used pure silver wire in some cases, and silver mesh in others, hooked up to a low-voltage electrical apparatus to deliver a steady stream of silver ions into the wound site. The researchers report in most cases that all infectious microorganisms were killed by the silver, and dramatic healing and even bone union took place. The researchers concluded, “Silver would appear to be the metal of choice for implanted electrodes used for bone stimulation. Its antibacterial properties, when it is the anode, would assist in controlling a quiescent pre-existing or operatively acquired infection. The results obtained with the silver-nylon electrode in open osteomyelitis would appear to warrant further investigation of its usage as an antibacterial dressing after wound debridement.”
The Antimicrobial Efficacy of Silver on Antibiotic-Resistant Bacteria Isolated From Burn Wounds
In this clinical study conducted by researchers from the Department of Pathology at West Virginia University, researchers found that when silver-ion emitting wound dressings containing two different kinds of silver compounds were exposed to a wide range of antibiotic-resistant bacteria, environments with lower pH (i.e., increased acidity) resulted in significantly greater antimicrobial activity compared to environments with higher pH (i.e., increased alkalinity). According to the researchers, “…when pH was changed from 8.5 to 5.5 antimicrobial activity for both dressings in general increased significantly (P < 0.05)… the study showed that the performance of both dressings apparently increased when pH became more acidic. The findings in this study may help to further enhance our knowledge of the role pH plays in affecting both bacterial susceptibility and antimicrobial activity of silver containing wound dressings.”
Antimicrobial Activity of Colloidal Silver Nanoparticles Prepared by Sol-Gel Method
In this clinical study, published in the Digest Journal of Nanomaterials and Biostructures, researchers from the Metallurgical and Material Science Engineering Department at Dokuz Eylul University in Turkey documented that colloidal silver nanoparticles in very low concentrations (i.e., 2-4 ppm) and at particle sizes of approximately 20-45 nm demonstrated a pronounced antibacterial effect against Escherichia coli, Staphylococcus aureus, Candida albicans, Bacillus subtilis, Salmonella typhimurium, Pseudomonas aeruginosa and Klebsiella pneumoniae.
Silver Nanoparticles Effective Against Tuberculosis Bacteria
In this study abstract, entitled “Nature-inspired novel drug design paradigm using nanosilver: efficacy on multi-drug-resistant clinical isolates of tuberculosis” the authors state that by capping silver nanoparticles with bovine serum albumin and then testing it in the laboratory against “clinical isolates collected from TB endemic areas” (i.e., sputum samples collected from pulmonary TB patients) they were able to demonstrate that this novel nanosilver compound constitutes a “potent anti-TB drug.” In the full study, which is available through the journal Current Microbiology (2011, 62:715-726), the authors further state, “Encouragingly, the results indicate that this novel design could be further extended for developing improved medicinal agents for combating multi-drug-resistant TB.”
The Silver Nanoparticle (Nano-Ag): A New Model for Antifungal Agents
In this study from the School of Life Sciences and Biotechnology, College of Natural Sciences, Kyungpook National University, Republic of Korea, silver nanoparticles were prepared and tested against clinical isolates of T. mentagrophytes and Candida fungal pathogens. The study authors conclude, “Nano-Ag also exhibited potent antifungal effects, probably through destruction of membrane integrity. To the author’s knowledge, this is the first study to apply Nano-Ag successfully to dermatophytes and pathogenic fungal strains. Secondly, the fact that preparation method of Nano-Ag described here is cost-effective is also of importance. Therefore, it can be expected that Nano-Ag may have potential as an anti-infective agent for human fungal diseases.”
Antifungal Activity and Mode of Action of Silver Nano-particles on Candida Albicans
In this abstract of a study conducted at the Department of Microbiology, College of Natural Sciences, at Kyungpook National University in South Korea, and published in the journal Biometals, researchers studied the anti-fungal effects of silver nano-particles and investigated their mode of action. The study authors concluded, “The results suggest nano-Ag may exert an antifungal activity by disrupting the structure of the cell membrane and inhibiting the normal budding process due to the destruction of the membrane integrity. The present study indicates nano-Ag has considerable antifungal activity, deserving further investigation for clinical applications.
Antifungal Effects of Silver Nanoparticle Alone and With Combination of Antifungal Drug on Dermatophyte Pathogen Trichophyton Rubrum
In this clinical study conducted at the Department of Biology, Islamic Azad University, and published by the 2011 International Conference on Bioscience, Biochemistry and Bioinformatics, researchers examined the effects of silver nanoparticles — alone, and in combination with two well-known anti-fungal drugs — on the dermatophyte fungi Trichophyton rubrum. The study authors found that “results of antifungal activity reveal that the growth of T. rubrum was inhibited at concentration of 10 µg/ml Ag-Nps alone.” The study authors also found that the antifungal activity of the drugs Flocunazole and Geriseofulvin were “increased in the presence of Ag-NP’s.” In short, silver nanoparticles demonstrated significant antifungal activity on their own, and when used in combination with antifungal drugs, they increased the antifungal efficacy of the drugs.
Antibacterial Activity and Mechanism of Silver Nanoparticles onEscherichia coli
In this clinical study conducted at the Guangdong Institute of Microbiology at Guangzhou, China, and published in 2010 in Applied Microbiology and Biotechnology, the researchers studied the antibacterial activity of silver nanoparticles against E. coli, as well as the mechanism through which silver nanoparticles provided inhibitory and bactericidal effects. The authors state, “The combined results suggest that silver nanoparticles may damage the structure of the bacterial cell membrane and depress the activity of some membranous enzymes, which cause E. coli bacteria to die eventually… For the first time, we offer evidences to indicate that silver nanoparticles can inhibit bacterial growth and even kill the cells through destroying bacterial membranous structure and permeability.”
Silver Nanoparticles Neutralize Hemorrhagic Fever Viruses
This is a recently unclassified presentation produced by the U.S. Department of Defense’s (DOD) Defense Threat Reduction Agency (DTRA) and the U.S. Strategic Command (USSTRATCOM) Center for Combating Weapons of Mass Destruction. It demonstrates the powerful neutralizing effects of silver nanoparticles against hemorrhagic fever viruses, including Arenavirus and Filovirus (i.e., Ebola). One of the main tasks of the DOD’s Defense Threat Reduction Agency is to “anticipate and mitigate future threats long before they have a chance to harm the United States and our allies.” The presentation was given by researchers from the Applied Biotechnology Branch, 711th Human Performance Wing of the Air Force Research Laboratory. The researchers concluded that in vitro, silver nanoparticles neutralize hemorrhagic fever viruses inside the cells by decreasing S segment gene expression and concomitantly decreasing progeny virus production. They note that viral neutralization occurs during the early phases of viral replication, so silver nanoparticle treatment would have to be administered prior to viral infection or within the first two to four hours after initial virus exposure.
Interaction of Silver Nanoparticles With Tacaribe Virus
Silver nanoparticles possess many unique properties that make them attractive for use in biological applications. An area that has been largely unexplored is the interaction of nanomaterials with viruses and the possible use of silver nanoparticles as an antiviral agent. This research focuses on evaluating the interaction of silver nanoparticles with a New World arenavirus, Tacaribe virus, to determine if they influence viral replication. This suggests that the mode of action of viral neutralization by silver nanoparticles occurs during the early phases of viral replication.
Role of Silver Ions in Destabilization of Intermolecular Adhesion Forces Measured by Atomic Force Microscopy in Staphylococcus epidermidis Biofilms
In this study published in the journal Antimicrobial Agents and Chemotherapy (Dec. 2005, American Society for Microbiology) it was revealed that Staphylococci epidermis biofilms have been found to be “markedly impaired” by very low, non-inhibitory levels of silver ions. This is important news, since biofilms give communities of microorganisms a distinct ability to resist antibiotic drugs. If low levels of silver ions can impair biofilms, then its use may well help resolve one factor in the growing problem of antibiotic-resistant microorganisms. According to the study authors, “Our AFM studies on the intermolecular forces within the EPSs of S. epidermidis RP62A and S. epidermidis 1457 biofilms suggest that the silver ions can destabilize the biofilm matrix by binding to electron donor groups of the biological molecules. This leads to reductions in the number of binding sites for hydrogen bonds and electrostatic and hydrophobic interactions and, hence, the destabilization of the biofilm structure… After the addition of silver ions and within 60 min of contact, the overall structure of the biofilm became partially destroyed and the inner structure of biofilm was exposed. There were also significant amounts of EPSs around the damaged biofilm colony, confirming the effect of silver ions on the grown biofilm matrix”
Axen 30 Ionic Colloidal Silver Solution Kills Campylobacter Jejuni in Minutes
Axen 30, a commercial disinfectant product consisting of a stabilized form of electrically generated ionic silver, demonstrated efficacy againstCampylobacter jejuni and therefore meets the requirements set forth by the U.S. EPA for disinfectant label claims. This essentially means the ionic silver solution killed this well-known food poisoning bacteria within exposure periods of two and five minutes. The EPA efficacy performance requirements for label claims state that the disinfectant must kill the microorganism on 10 out of 10 inoculated carriers or the label claims cannot be approved. According to the study conclusion, “Under the conditions of this investigation, Axen 30…demonstrated efficacy against Campylobacter jejuni as required by the U.S. EPA for disinfectant label claims following two and five minute exposure periods.”
A Pharmacological and Toxicological Profile of Silver as an Antimicrobial Agent in Medical Devices
This is an impressive review of the available medical data regarding the pharmacology and toxicology of silver used as an antimicrobial agent in medical devices. Published in the journal Advances in Pharmacological Sciences, and written by Alan B. G. Lansdown, the well-known British researcher and author of the definitive guide to the use of silver in medical situations, Silver in Healthcare: It’s Antimicrobial Efficacy and Safety in Use(Issues in Toxicology, RSC Publishing). The review concludes, in part, “Silver should not be regarded as a cumulative poison…Only in cases of chronic systemic silver overload situations where excretory mechanisms become saturated, does silver deposit in an inert fashion in lysosomal or intercellular sites, unrelated to tissue damage. In these situations, selenium serves as a major protective factor in precipitating the silver in a highly insoluble and hence inert form of silver selenide.”
Silver In Drinking Water — World Health Organization Guidelines
In this report the World Health Organization discusses the maximum allowable amount of silver allowed in drinking water, and reports that the “biological half-life (of silver) in humans ranges from several days to 50 days. According to the report, the liver plays the main role in the elimination of silver from the body. And most ingested silver is excreted in the feces, with cumulative excretion rates between 90-99%. The report states, “The only known clinical picture of chronic silver intoxication is that of argyria, a condition in which silver is deposited on skin and hair, and in various organs following occupational or iatrogenic exposure to metallic silver and its compounds, or the misuse of silver preparations.” The report concludes, “On the basis of present epidemiological and pharmacokinetic knowledge, a total lifetime oral intake of about 10 g of silver can be considered as the human NOAEL [i.e., No Observable Adverse Effect Level]…Higher levels of silver, up to 0.1 mg/litre (a concentration that gives a total dose over 70 years of half the human NOAEL of 10 g), could then be tolerated without risk to health.”
Toxicological Profile for Silver — Agency for Toxic Substances and Disease Registry
In this U.S. Public Health Service report from the Agency for Toxic Substances and Disease Registry, the health and toxicological effects of silver ingested or absorbed through various means are examined. The report states that most of the silver that is eaten or breathed in leaves the body in the feces within about a week. And that argyria (i.e., skin discoloration) is the “most serious heath effect” of excessive silver exposure. According to the report, “It is likely that many exposures to silver are necessary to develop argyria. Once you have argyria it is permanent. However, the condition is thought to be only a ‘cosmetic’ problem. Most doctors and scientists believe that the discoloration of the skin seen in argyria is the most serious health effect of silver.” The report concludes, “Populations that are unusually susceptible to toxic effects of silver exposure are those that have a dietary deficiency of vitamin E or selenium, or that may have a genetically based deficiency in the metabolism of these essential nutrients. Individuals with damaged livers may also be more susceptible to the effects of silver exposure. In addition, populations with high exposures to selenium may be more likely to develop argyria. Furthermore, some individuals may exhibit an allergic response to silver.”
The Effect of Nano-Silver Liquid against the White Rot of the Green Onion Caused by Sclerotium cepivorum
In this breakthrough study, published in the March 2010 issue of the journalMycobiology, researchers found that applying varying levels of silver nanoparticles to the roots of green onion plants completely eradicatedSclerotium cepivorum fungal infections known to destroy the plants. Not only did the application of silver nanoparticles destroy the pathogenic plant fungus, but according to the study authors, it caused no harm whatsoever to beneficial soil microbes needed by the green onion plants for growth, nor was there any negative change in the soil chemistry or composition. What’s more, the nanosilver-treated green onion plants, once harvested, were demonstrated to have grown larger and to weigh more than the non-treated green onion plants. Finally, the study researchers pointed out that the more they increased the use of nanosilver on the green onion plants, the lower the level of silver being absorbed into the plant itself. The researchers stated, “When the amount of nano-silver was calculated in the plants grown in nano-silver treated soil, it was found that the concentration of nano-silver used for treatment and the concentration of nano-silver found in the plants was inversely proportional.” In other words, the plants themselves apparently reduce absorption of the nanosilver when higher levels are used on them to control the plant blight. The conclusion drawn by the study researchers was staggering in its implications: “Nano-silver liquid for the prevention of various plant pathogenic fungi is highly recommended to farmers. Additionally, the use of nano-silver does not cause any harm to human beings, and it is safe for the environment and agricultural products. In conclusion, we can say that by using nano-silver liquid, environmental pollution and the excessive use of chemical compounds in the field can be reduced. It is expected that the application of nano-silver at low concentrations will be economic, eco friendly, and decrease farm management costs.”
Silver Enhances Antibiotic Activity Against Gram-Negative Bacteria
In this June 2013 clinical study published in the journal Science Translational Medicine, titled “Silver Enhances Antibiotic Activity Against Gram-Negative Bacteria,” it was documented by the study authors that antimicrobial silver could be used to help restore the effectiveness of antibiotic drugs by up to 1,000%. The authors state, “We show that silver disrupts multiple bacterial cellular processes, including disulfide bond formation, metabolism, and iron homeostasis. These changes lead to increased production of reactive oxygen species and increased membrane permeability of Gram-negative bacteria that can potentiate the activity of a broad range of antibiotics against Gram-negative bacteria in different metabolic states, as well as restore antibiotic susceptibility to a resistant bacterial strain.” The authors also revealed that silver-treated bacteria weren’t even able to produce a biofilm, and that when drug-resistant biofilms were treated with silver, the bacterial resistance to antibiotic drugs was negated. Finally, the silver/antibiotic drug combinations tested were able to eradicate bacterial persister cells which can otherwise result in multi-drug tolerance and relapsing chronic infections.
Silver In Health Care: Antimicrobial Effects and Safety In Use
This study, published in the journal Current Problems in Dermatology (2006;33:17-34) is by one of Britain’s top experts in antimicrobial silver, Alan B. Lansdown of the Imperial College Faculty of Medicine, Charing Cross Hospital in London, UK. He writes, “Silver has a long and intriguing history as an antibiotic in human health care. It has been developed for use in water purification, wound care, bone prostheses, reconstructive orthopaedic surgery, cardiac devices, catheters and surgical appliances. Advancing biotechnology has enabled incorporation of ionizable silver into fabrics for clinical use to reduce the risk of nosocomial infections and for personal hygiene. 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 exhibits low toxicity in the human body, and minimal risk is expected due to clinical exposure by inhalation, ingestion, dermal application or through the urological or haematogenous route. Chronic ingestion or inhalation of silver preparations (especially colloidal silver) can lead to deposition of silver metal/silver sulphide particles in the skin (argyria), eye (argyrosis) and other organs. These are not life-threatening conditions but cosmetically undesirable. Silver is absorbed into the human body and enters the systemic circulation as a protein complex to be eliminated by the liver and kidneys. Silver metabolism is modulated by induction and binding to metallothioneins. This complex mitigates the cellular toxicity of silver and contributes to tissue repair. Silver allergy is a known contra-indication for using silver in medical devices or antibiotic textiles.”
Inhibitory Effects of Silver Nanoparticles on H1N1 Influenza A Virus In Vitro
In this study, published in the Journal of Virological Methods in December 2011, the study authors concluded that silver nanoparticles were able to inhibit H1N1 influenza A virus. According to the study authors, “In this study, the interaction of silver nanoparticles with H1N1 influenza A virus was investigated…This study demonstrates that silver nanoparticles have anti-H1N1 influenza A virus activities. The inhibitory effects of silver nanoparticles on influenza A virus may be a novel clinical strategy for the prevention of influenza virus infection during the early dissemination stage of the virus.”
Silver Nanoparticles Inhibit Hepatitis B Virus Replication
In this study, published in the journal Antiviral Therapy in 2008, researchers from the Department of Medicine, University of Hong Kong, demonstrated the silver nanoparticles could be used to inhibit the replication of hepatitis B virus due to the ability to bind with the viral DNA. According to the study authors, “Silver nanoparticles have been shown to exhibit promising cytoprotective activities towards HIV-infected T-cells; however, the effects of these nanoparticles towards other kinds of viruses remain largely unexplored. The aim of the present study was to investigate the effects of silver nanoparticles on hepatitis B virus (HBV)…. The in vitro anti-HBV activities of these particles were determined using the HepAD38 cell line as infection model… an absorption titration assay showed that the nanoparticles have good binding affinity for HBV DNA… we found that Ag10Ns could directly interact with the HBV viral particles as revealed by transmission electronic microscopy.” The study authors concluded, “Silver nanoparticles could inhibit the in vitro production of HBV RNA and extracellular virions. We hypothesize that the direct interaction between these nanoparticles and HBV double-stranded DNA or viral particles is responsible for their antiviral mechanism.”
Inactivation of Microbial Infectiousness By Silver Nanoparticles-Coated Condom: A New Approach to Inhibit HIV- and HSV-Transmitted Infection
In this remarkable study published in the International Journal of Nanomedicine in 2012, the study authors found that coating condoms with silver nanoparticles helped inhibit the infectivity of both HIV (i.e., Human Immunodeficiency Virus) and HSV (i.e., Herpes simplex virus), as well as bacterial and fungal microbes. The study authors stated, in part, “Recent research suggests that today’s condoms are only 85% effective in preventing human immunodeficiency virus (HIV) and other sexually transmitted diseases. In response, there has been a push to develop more effective ways of decreasing the spread of the disease. The new nanotechnology-based condom holds the promise of being more potent than the first-generation products. The preliminary goal of this study was to develop a silver nanoparticles (Ag-NPs)-coated polyurethane condom (PUC) and to investigate its antimicrobial potential including the inactivation of HIV and herpes simplex virus (HSV) infectiousness… No significant toxic effects was observed when human HeLa cells, 293T and C8166 T cells were contacted to Ag-NPs-coated PUC for three hours. Interestingly, our results demonstrated that the contact of the Ag-NPs-coated PUC with HIV-1 and HSV-1/2 was able to efficiently inactivate their infectiousness… Furthermore, we also showed that the Ag-NPs-coated PUC was able to inhibit the growth of bacteria and fungi. These results demonstrated that the Ag-NPs-coated PUC is able to directly inactivate the microbe’s infectious ability and provides another defense line against these sexually transmitted microbial infections.”
In vitro Antifungal Activity of Silver Nanoparticles Against Ocular Pathogenic Filamentous Fungi
In this study, published in the Journal of Ocular Pharmacology and Therapeutics in March 2013, the study authors focused on determining whether or not silver nanoparticles could be used as an effective treatment for fungal keratitis, which is emerging as a “major cause of vision loss” in China and other developing nations due largely to the unavailability of effective antifungals. According to the study authors, “It is urgent to explore broad-spectrum antifungals to effectively suppress ocular fungal pathogens, and to develop new antifungal eye drops to combat this vision-threatening infection. The aim of this study is to investigate the antifungal activity of silver nanoparticles (nano-Ag) in comparison with that of natamycin against ocular pathogenic filamentous fungi in vitro… Susceptibility tests were performed against 216 strains of fungi isolated from patients with fungal keratitis.” The researchers concluded that silver nanoparticles “…exhibit potent in vitro activity against ocular pathogenic filamentous fungi”.
Clinical Observation of Gelatamp Colloidal Silver Gel Sponge on the Treatment of Pericoronitis
In this clinical study, published in the International Journal of Stomatology in 2010 (Vol. 37, Issue 3), researchers using a colloidal silver gelatin sponge called Gelatamp studied 227 patients with third molar pericoronitis, which is an infection and inflammation of the soft tissues, gingiva and dental follicle around the molar tooth. They divided the patients up into two groups, one of which received treatment with the Gelatamp oral colloidal silver gelatin sponge used in the deep soft tissue pocket around the tooth, and the other using Iodine Glycerol in the soft tissue pocket, instead. According to the study authors, “The clinical effects were evaluated….Group Gelatamp colloidal silver gelatin sponge had better clinical effects than group Iodine Glycerol…Gelatamp colloidal silver gelatin sponge…effectively improved the clinical symptom and clinical results.”
Colloidal Silver Fabrication Using the Spark Discharge System and Its Antimicrobial Effect on Staphylococcus aureus
In this study, published in the journal Medical Engineering & Physics, the researchers used a unique method to create a stable colloidal silver solution consisting of both silver nanoparticles and silver ions. The solution was then tested for antimicrobial effect against Staphylococcus aureus. According to the study authors “Traditional chemical synthesis methods for colloidal silver may lead to the presence of toxic chemical species or chemical residues, which may inhibit the effectiveness of colloidal silver as an antibacterial agent. To counter these problems a spark discharge system (SDS) was used to fabricate a suspension of colloidal silver in deionized water with no added chemical surfactants.” This resulted in a solution that “contains both metallic silver nanoparticles and ionic silver foms.” The researchers then studied the antimicrobial effects of this solution on the Staph pathogen. They concluded, “The results show that colloidal silver 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.” In other words, the silver ions were found to be the active, infection-fighting specie of silver.
Spectrum of Antimicrobial Activity Associated With Ionic Colloidal Silver
In this study, published in the Journal of Alternative and Complementary Medicine in March 2013, researchers tested an ionic colloidal silver product against “several strains of bacteria, fungi, and viruses” that were “grown under multicycle growth conditions in the presence or absence of ionic colloidal silver in order to assess the antimicrobial activity.” According to the researchers, “…the Food and Drug Administration currently does not recognize colloidal silver as a safe and effective antimicrobial agent. The goal of this study was to further evaluate the antimicrobial efficacy of colloidal silver.” The researchers found that “significant inhibition was observed” for bacteria grown under aerobic (oxygen rich) or anaerobic (oxygen poor) conditions. However, the effect of the ionic silver “varied significantly” on fungal cultures, depending upon the strain or genera of fungus treated. And no viral growth inhibition was observed for the viruses tested. The study authors concluded, “The study data support ionic colloidal silver as a broad-spectrum antimicrobial agent against aerobic and anaerobic bacteria, while having a more limited and specific spectrum of activity against fungi.”
Anti-Leishmanial Effect of Silver Nanoparticles and their Enhanced Anti-Parastic Activity Under UV Light
According to this clinical study, published in the International Journal of Nanomedicine in November 2011, researchers found for the first time that silver nanoparticles are effective against the Leishmaniasis pathogen — a protozoan parasite that causes Leishmaniasis, a disease that is potentially fatal if left untreated, and which causes ulcers of the skin, mouth and nose, plus fever, anemia and enlarged spleen and liver. Leishmaniasis is currently endemic in 98 countries worldwide, affecting some 12 million people. The researchers demonstrated that silver nanoparticles significantly inhibited the infectivity of the Leishmaniasis pathogen, “inhibiting all biological activities of the parasite.” The study authors concluded, “Therefore, the authors consider a new approach, one that includes the application of Ag-NPs on vectors that carry infective Leishmania promastigotes, may be offered in the near future, and that this may prevent the disease from spreading… The results clearly show there is no need to apply high concentrations of Ag-NPs for inhibiting amastigotes, and this may be very promising for the treatment of leishmaniasis…Since leishmaniasis is spreading rapidly worldwide and because anti-leishmanial drugs have several disadvantages, the authors posit that treatment based on silver nanoparticles may have a very important role in overcoming leishmaniasis.”
Colloidal Silver Nanoparticles for the Prevention of Gastrointestinal Bacterial Infections
In this clinical study, published in the journal Advances in Natural Sciences: Nanoscience and Technology, researchers found that colloidal silver nanoparticles were extremely effective against two key forms of gastrointestinal bacteria responsible for serious infections, i.e., Escherichia coli (ATCC 43888-O157:k-:H7) and Vibrio cholera (O1). The research team demonstrated that the silver solution provided stronger and longer-lasting surface disinfection than conventional chemical disinfectants and surmised it could be effectively used in place of them. The researchers concluded, “In this work, we investigated the antibacterial and disinfectant activity of colloidal silver NPs which were prepared by a UV-enhanced photochemical method….It was found that our silver NPs colloid exhibited strongly effective antibacterial effect against tested gastrointestinal bacteria at a silver concentration as low as ~3 mg l-1. Interestingly, the silver NPs colloid displayed enhanced antimicrobial performance and longer lasting disinfectant effect as compared to the conventional chloramin B disinfection agent. With these exhibited advantages, the as-prepared colloidal silver NPs are very promising for use in treatment of environments containing gastrointestinal bacteria or other infectious pathogens.”
Rice University: Ions, Not Particles, Make Silver Toxic to Bacteria
In this press release from Rice University, clinical researchers discuss the results of their new study titled “Negligible Particle-Specific Antibacterial Activity of Silver Nanoparticles,” which was published in the July 5, 2012 issue of the journal Nano Letters. In their study, the researchers demonstrate conclusively that silver ions, and not metallic silver particles (i.e., nanosilver) are what make silver toxic to bacteria. The researchers found that the metallic (i.e., nanoparticle) form of silver is largely inert, and cannot kill pathogens except to the extent in sheds silver ions in the presence of pathogens. According to the study abstract, “For nearly a decade, researchers have debated the mechanisms by which AgNPs exert toxicity to bacteria and other organisms. The most elusive question has been whether the AgNPs exert direct ‘particle-specific’ effects beyond the known antimicrobial activity of released silver ions (Ag+). Here, we infer that Ag+ is the definitive molecular toxicant. We rule out direct particle-specific biological effects by showing the lack of toxicity of AgNPs when synthesized and tested under strictly anaerobic conditions that preclude Ag(0) oxidation and Ag+ release.”
Colloidal Silver: A Novel Treatment for Staphylococcus aureusBiofilms
In this study, published in the journal International Forum of Allergy & Rhinology in March 2014, the study authors begin by explaining that a patient with a “previously recalcitrant Staphylococcus aureus-infected chronic rhinosinusitis” began using a colloidal silver product as a nasal spray, and experienced marked improvement. The study authors then decided to test “whether colloidal silver has any direct bactericidal effects on these biofilms in vitro.” In other words, they wanted to see for themselves if colloidal silver killed Staphylococcus aureus under strict laboratory conditions. The researchers used various dilutions of colloidal silver. What they discovered was that except for the very lowest dilution used, the colloidal silver dramatically reduced the S. aureus biomasses. “At 20 uL colloidal silver, the reduction in biomass was 98.9%…a maximum biomass reduction of 99.8% was reached at both 100 and 150 uL colloidal silver. The study authors concluded, “Colloidal silver directly attenuates in vitro S. aureus biofilms.”


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s