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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
In this study published in 2010 in the Journal of Experimental & Clinical Cancer Research, the study authors decided to test colloidal silver against human breast cancer cells. According to the study authors, “The aim of this study was to determine if colloidal silver had cytotoxic effects on MCF-7 breast cancer cells and its mechanism of cell death.” The breast cancer cells were treated with colloidal silver ranging from 1.75 ppm to 17.5 ppm in concentration, for five hours. Results: “Colloidal silver demonstrated dose-dependent cytotoxic effect in MCF-7 breast cancer cells through induction of apoptosis.” In essence, this means the colloidal silver created changes in the cancer cells that led them to commit cellular suicide. The researchers also discovered that colloidal silver killed the breast cancer cells without causing toxicity or harm to normal control cells, i.e., “Our in vitro studies showed that colloidal silver induced a dose-dependent cell death…without affecting the viability of normal PBMC control cells.” Finally, the researchers concluded, “The overall results indicated that the colloidal silver has antitumor activity through induction of apoptosis in MCF-7 breast cancer cell line, suggesting that colloidal silver might be a potential alternative agent for human breast cancer therapy.”
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.” In other words, only 3.42 ppm nanosilver was necessary in order to cause 50% of the cancer cells to die. (The study demonstrated that higher concentrations of nanosilver caused an even greater percentage of cell death.) 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
This clinical study, published in September 2010 in the International Journal of Nanomedicine, confirms the antitumor properties of silver nanoparticles, and suggests they may be a cost-effective alternative in the treatment of cancer. According to the study authors, “The present study demonstrates the efficacy of biologically synthesized silver nanoparticles (AgNPs) as an antitumor agent using Dalton’s lymphoma ascites (DLA) cell lines in vitro and in vivo. The AgNPs showed dose-dependent cytotoxicity against DLA cells through activation of the caspase 3 enzyme, leading to induction of apoptosis which was further confirmed through resulting nuclear fragmentation. Acute toxicity, i.e., convulsions, hyperactivity and chronic toxicity such as increased body weight and abnormal hematologic parameters did not occur.” In other words, silver nanoparticles not only caused the cancer cells to self-destruct – both in the test tube model and in the animal model in which breast cancer was induced in mice -- but when tested in the animal model the silver caused no signs of toxicity or harm to the test subjects. This led the study authors to conclude, “Taken together, our data suggest that silver nanoparticles can induce cytotoxic effects on DLA cells, inhibiting tumor progression and thereby effectively controlling disease progression without toxicity to normal cells.”
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+ (i.e., ionic colloidal silver) could play a pivotal role in overcoming cancerous processes. The authors of this white paper reviewed many of those findings and offer some dramatic case histories of cancers being cured in human test subjects. The authors wrote, “Silver-based drugs have one core common denominator – their active ingredient is their content of “oligodynamic” silver ions (i.e., Ag+ )… Modern nanoscience is still making new discoveries regarding oligodynamic metals. Nanoscientists appear positioned to develop some of the most complicated strategies for fighting cancer. For example, they are discovering that cancer drugs must be able to easily disrupt and penetrate tumor cell membranes in situ to enable the fullest possible oncolytic effects. Picoscalar or nearpicoscalar oligodynamic Ag+ hydrosol enjoys the greatest surface presentation (i.e., ~ 6 km2 per gram Ag) for tumor cell membrane adherence and penetration, leading to greater oncolytic effects.” After providing insights into some of the most recent clinical studies the author’s concluded, “It has long been suspected that infectious agents are associated with solid tumor cancers (a notable example is Kaposi’s Sarcoma) as well as non-tumor based cancers such as leukemia…Oligodynamic Ag+ may have the potential to play a dual role: either destroy the infectious etiological agent of the cancer, and/or destroy the pathogen loads arising within immunocompromised patients.”
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 Nanobiotechnology demonstrating 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 the Journal 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 on Escherichia 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 against Campylobacter 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 journal Mycobiology, researchers found that applying varying levels of silver nanoparticles to the roots of green onion plants completely eradicated Sclerotium 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 aureus Biofilms
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."
Silver Ions in the Treatment of Local Infections
In this 1999 study published in the journal Metal-Based Drugs, Dr. Robert O. Becker, M.D., documents his two decades worth of research into the use of electrically generated silver ions to cure local infections, including treatment of "over 100 cases of recalcitrant osteomyelitis (i.e., osteomyelitis infections that did not respond to traditional antibiotic drugs) with an overall success rate of approximately 65% and no evidence of argyria." Dr. Becker ultimately switched from the use of electrically generated silver ions in wound care to the use of silver-coated nylon fabric, which releases silver ions en masse directly into covered wound sites. This study documents that transition. As he wrote at the time: “Both the silver iontophoresis technique and the simple application of the silver fabric in wound care utilize no agent other than free silver ions given off into the wound as the primary anti-bacterial agent…At present, silver ions appear to have the broadest spectrum of anti-bacterial activity. The level of free silver ions produced in the wound is greater than with any silver compound presently available. The method of use is simple and dressing changes are easy and non-painful.”
Nanosilver Stops Activation of Nasal Polyp Epithelial Cells
Here’s some potentially good news for people suffering from nasal polyps -- a relatively new clinical study published in the journal International Immunopharmacology in November 2011, demonstrated that nanosilver has significant anti-inflammatory affects on “respiratory epithelial cell inflammation,” meaning it stops the cells of nasal polyps from becoming inflamed. This, of course, was a test tube study and not a real-life study. According to the Abstract of the study, “The aim of this study was to investigate the potential clinical efficacy of nano-silver for its anti-inflammatory effect on respiratory epithelial cell inflammation.” In other words, the researchers wanted to know if nano-silver could stop the inflammation that characterizes nasal polyp cells. The researchers concluded “…cell survival was found to be significantly decreased at nano-silver concentrations exceeding 10 ppm.” In other words, the abnormal cells that make up the nasal polyps started dying upon exposure to 10 ppm nanosilver. According to the researchers, “…at safe concentrations nanosilver can inhibit the activation of NPECs [i.e., nasal polyp epithelial cells – ED]. This finding suggests a novel pharmacological rationale for the treatment of airway inflammation and/or immunological disease.” In short, based on this strictly preliminary clinical study, it appears that antimicrobial silver (perhaps used as a nasal wash) might be helpful in terms of at least inhibiting the inflammation that characterizes nasal polyp cells. It might even help kill the cells that make up the polyps.
Nanosilver Non-Toxic in New Human Clinical Study
In a brand new clinical study titled “In vivo Human Time-exposure Study of Orally Dosed Commercial Silver Nanoparticles,” published in October 2014 in the journal Nanomedicine, clinical researchers from the University of Utah demonstrated the lack of toxicity to humans of orally-ingested nanoscale colloidal silver at both 10 ppm and 32 ppm concentrations. According to the study authors, “We prospectively studied commercial 10- and 32-ppm nanoscale silver particle solutions in a single-blind, controlled, cross-over, intent-to-treat, design. Healthy subjects (n = 60) underwent metabolic, blood counts, urinalysis, sputum induction, and chest and abdomen magnetic resonance imaging. Silver serum and urine content were determined. No clinically important changes in metabolic, hematologic, or urinalysis measures were identified. No morphological changes were detected in the lungs, heart or abdominal organs. No significant changes were noted in pulmonary reactive oxygen species or pro-inflammatory cytokine generation. In vivo oral exposure to these commercial nanoscale silver particle solutions does not prompt clinically important changes in human metabolic, hematologic, urine, physical findings or imaging morphology. Further study of increasing time exposure and dosing of silver nanoparticulate silver, and observation of additional organ systems are warranted to assert human toxicity thresholds.” In short, no toxicity whatsoever to the human body was demonstrated during the 14-day trial. The researchers concluded, “We have demonstrated that 14- day monitored human oral dosing of a commercial oral nanoparticle silver colloidal product does not produce observable clinically important toxicity markers. Further study of nanomaterials over longer human exposures is clearly warranted…”
Nanosilver Kills Tuberculosis Pathogen at Low Levels
A clinical study titled “Fabrication of Silver Nanoparticles and Their Antimicrobial Mechanisms,” published in 2006 in the journal European Cells and Materials (Vol. 11), demonstrated that silver nanoparticles at a concentration of only 10 ppm was effective against Mycobacterium tuberculosis. The researchers stated: “Silver nanoparticles were successfully produced less than 10nm in size. They showed excellent antibacterial activities against S. typhi, E. coli, P. aeruginosa around 1 ppm and S. aureus and M. tuberculosis around 10 ppm. Three types of antimicrobial mechanisms were observed: 1) Plasmolysis, cytoplasm of bacteria separated from bacterial cell wall, was observed in Gram negative bacteria 2) The synthesis of bacterial cell wall was inhibited in S. aureus. 3) Nanosilver particles found in the cytoplasm of M. tuberculosis may induce metabolic disturbance.” The researchers concluded: “Silver nanoparticles…showed excellent antibacterial activity. Antimicrobial mechanisms of nanosilver were different according to the species of bacteria. From the result, silver nanoparticles will be available as a good antibiotic alternative.” In short, silver nanoparticles “induced metabolic disturbance” in Mycobacterium tuberculosis, and killed them at 10 ppm, while killing Staphylococcus aureus, Pseudomona aeruginosa and Escherichia coli at only 1 ppm.
Antibacterial Activity of Silver-killed Bacteria: the "Zombies" Effect
Most researchers agree that silver kills bacteria in a three-fold manner, i.e., catalytic oxidation, cell wall disruption and penetration leading to disabling of the bacterium’s respiration and energy transfer systems, and prevention of replication by attaching to the DNA of the pathogen. What happens afterwards is what researchers did not know until now. In this clinical study from researchers at the Hebrew University of Jerusalem, published in the journal Scientific Reports in April 2015, it was discovered that the pathogens killed by silver then go on to kill other pathogens in the same colony. This is because as they die, they absorb more silver, like a sponge. This absorbed silver is then able to leach into the remainder of the bacterial colony, killing even more bacteria. In essence, the dead bacteria become “zombies,” spreading death throughout the rest of the colony thanks to their close proximity. In the preface to the study, the researchers state, “We report a previously unrecognized mechanism for the prolonged action of biocidal agents, which we denote as the zombies effect: biocidally-killed bacteria are capable of killing living bacteria. The concept is demonstrated by first killing Pseudomonas aeruginosa PAO1 with silver nitrate and then challenging, with the dead bacteria, a viable culture of the same bacterium: Efficient antibacterial activity of the killed bacteria is observed. A mechanism is suggested in terms of the action of the dead bacteria as a reservoir of silver, which, due to Le-Chatelier's principle, is re-targeted to the living bacteria.” In other words, when dead bacteria that were killed by silver are exposed to living bacteria, the living bacteria are in turn killed.
Silver Nanoparticles Help Cut Flowers Live Longer
In a clinical study titled “Improvement of Vase Life and Post-harvest Factors of Lilium orientalis Bouquet by Silver Nanoparticles,” scientists from the Department of Horticulture at Ferdowsi University of Mashhad, Iran tested the hypothesis that silver nanoparticles would help cut flowers live longer by reducing microbial growth in the vase. Using suspensions of silver nanoparticles in water at concentrations of 5, 15, 25, 30 parts per million (ppm) and comparing the floral arrangements against controls with untreated vase water, the researchers found that the cut flowers lived up to twice as long in the silver-treated solutions. In their clinical study, the researchers concluded, “Owing to its strong antibacterial properties, silver nanoparticles are dramatic tools for extending cut flowers post harvest life.” The researchers also pointed out that even at the highest concentration used (i.e., 30 ppm) there were no apparent toxic effects on the flowers. What’s more, the ability of the cut flowers to uptake nutrients decreased rapidly in the control flower arrangements that had no silver added, while the nutrient uptake of the flowers arrangements in the silver-treated water barely decreased during the lifetime of the cut flowers. Finally, the fresh weight of the control flowers that were not treated with silver nanoparticles dropped significantly over a period of several days, while the silver nanoparticles-treated flowers “maintained fresh weight at high values” according to the researchers.
The Increasing Use of Silver-based Products as Antimicrobial Agents
In this interesting review of clinical literature, published in August 2015 in the Oxford Journal’s Journal of Antimicrobial Chemotherapy (Vol. 59, Issue 4, Pp. 587-590), the author discusses the idea that while clinical incidence of silver resistance among bacteria remains quite low (with a meager 20 clinical examples since 1975), several important standards for the use of antimicrobial silver in wound dressings need to be developed in order to make sure the clinical threat of silver resistance remains low. The author discussed the need for the development of standardized testing methods for determining antimicrobial silver’s MIC values (i.e., minimum inhibitory concentration values) in wound dressings. He also discussed the need for the development of recognized breakpoints and of the need to determine the best methods of release of silver ions for maximum effectiveness. The author concluded that wound dressings that release low levels of silver ions are more likely to contribute to additional incidences of silver resistance in the future than products that release higher levels of silver ions and thus exhibit a faster and more efficient rate of bactericidal activity. According to the study author, “In order to minimize the risk of silver resistance, clinicians should choose dressings that release high levels of silver ions and that demonstrate rapid bactericidal activity.”
Cytotoxicity and genotoxicity of silver nanoparticles in the human lung cancer cell line, A549
In this clinical study published in the Archives of Toxicology in July 2011, researchers discovered that when a human lung cancer cell line A549 was exposed to silver nanoparticles, reactive oxygen species (ROS) was produced resulting in mitochondrial damage to the cancer cells and “early apoptosis” (i.e., cellular self-destruction). The researchers found that if the cancer cells were pre-treated with N-acetyl-cysteine (a modified form of the amino acid cysteine, known for its powerful antioxidant properties) there was less damage to the DNA of the cancer cells. This indicates that a primary mode of effectiveness of silver nanoparticles against cancer cells is its ability to create reactive oxygen species in the presence of these cells, which in turn damages their DNA resulting in early cell death.
Anti-proliferative activity of silver nanoparticles
In this clinical study, published in the journal BMC Cell Biology in September 2009, researchers discovered that when human glioblastoma cells (malignant brain cancer cells) were exposed to silver nanoparticles, the cancer cells engulfed the silver particles (via endocytosis) resulting in chromosomal instability and mitotic arrest (i.e., the cancer cells can no longer divide efficiently in order to form new cancer cells). This, in turn, resulted in DNA breakdown and cellular apoptosis (cellular self-destruction). In short, silver caused the brain cancer cells to stop replicating, and die. The researchers compared the silver-treated brain cancer cells with silver-treated normal human fibroblast cells, and found that the normal human cells exhibited “efficient recovery” from the effects of the silver particles, while the cancer cells were “susceptible to damage with lack of recovery from Ag-np-induced stress.” In other words, the silver particles did not kill normal cells, but did kill the cancer cells.
In vitro toxicity of silver nanoparticles at noncytotoxic doses to HepG2 human hepatoma cells
In this clinical study, published in the journal Environmental Science & Technology in August 2009, silver nanoparticles were tested in very small concentrations on human hepatoma cell line HepG2 (a liver cancer cell line). The silver-treated cells were then compared to cells treated with polystyrene nanoparticles and silver carbonate (a chemical silver compound) in order to “test the toxic effects with respect to different raw chemical compositions and forms of silver.” Interestingly, at very low concentrations of only one-half ppm, the silver appeared to accelerate cell proliferation. But at concentrations of 1 ppm and higher, the silver particles “induced abnormal cellular morphology” displaying “cellular shrinkage and acquisition of an irregular shape.” The researchers concluded that “both nanosized particles of silver as well as ionic silver contribute to the toxic effects of Ag-NPs” against the cancer cells.
Silver Nanoparticles Biosynthesized Using Achillea biebersteinii Flower Extract: Apoptosis Induction in MCF-7 Cells via Caspase Activation and Regulation of Bax and Bcl-2 Gene Expression
In this clinical study, published in February 2015 in the journal Molecules, researchers treated a human breast cancer cell line with silver nanoparticles that were synthesized using flowers from the Yarrow herb (Achillea biebersteinii). The researchers acknowledged previous research demonstrating that silver nanoparticles have been demonstrated to be toxic against cancer cell lines, and concluded that their “green”-synthesized silver nanoparticles worked equally as well, stating, “The cells were exposed to various concentrations of Ag-NPs for 24 h and 48 h then the toxicity effects of Ag-NPs assessed using the MTT assay. The MTT results showed that the Ag-NPs decreased cell viability on a dose and time-dependent basis. The inhibitory concentration (IC50 value) was 20 µg/mL after 24 h of cell treatment. It is similar to IC50 that reporting with other researchers.” In other words, similar to the results of other clinical studies, the 20 ppm concentration of silver nanoparticles used by the researchers killed half of the cancer cells after just 24 hours of treatment. The researchers concluded, “In summary, our data indicated that the biosynthesized silver nanoparticles induced apoptosis on MCF-7 cell line… Biosynthesized silver nanoparticles from Achillea biebersteinii flower extract could be considered a potential chemotherapeutic agent in the treatment of breast cancer.”
Silver Nanoparticles Induce Degradation of the Endoplasmic Reticulum Stress Sensor Activating Transcription Factor-6 Leading to Activation of the NLRP-3 Inflammasome
In this clinical study, published in February 2015 in the Journal of Biological Chemistry, the study authors set out to discover whether or not silver nanoparticles could cause harm to human cells. But what the actually discovered surprised them: Silver nanoparticles are toxic to leukemia cells. In their experiments, the researchers used tiny, 15 nm sized silver nanoparticles on human human monocyte and macrophage cells. They found that at low concentrations, the silver nanoparticles induced stress in the endoplasmic reticulum of the cells, but didn’t cause cell death. But at higher concentrations, the silver nanoparticles caused apoptosis, which is to say, it caused the cells to self-destruct. Some researchers have cited this study as “proof” that silver nanoparticles are harmful to normal human cells. However, that’s a disingenuous conclusion, when you consider the fact that a.) previous clinical studies have demonstrated silver nanoparticles cause cancer cells to self-destruct while leaving normal human cells largely unscathed, and b.) the researchers behind this study admit they used human leukemia cells throughout most of the study. According to the lead study author, Professor Denis Girard, in a news release published on, “We used leukemia cells throughout most of the study. The question is, could we achieve the same results with other types of cancer cells? If so, it may be possible to use nanoparticles to kill cancer cells without the use of drugs, which would be very promising.” So what the researchers actually discovered, perhaps inadvertently, is that silver nanoparticles cause human leukemic cancer cells to self-destruct.
Colloidal Silver Nanoparticles Improve Anti-leukemic Drug Efficacy via Amplification of Oxidative Stress
In this clinical study, published in the journal Colloids and surfaces. B, Biointerfaces in February 2015, researchers demonstrated that when silver nanoparticles are added to anti-leukemia drugs, the silver improved the effectiveness of the drugs by amplifying oxidative stress on the leukemic cancer cells. The study authors wrote, “It has been known that silver nanoparticles (AgNPs) display anti-leukemic activity via ROS overproduction. Hence, we hypothesized that AgNPs could improve therapeutic efficacy of ROS-generating agents against leukemia cells.” The study authors concluded, “Taken together, these results reveal that AgNPs combined with ROS-generating drugs could potentially enhance therapeutic efficacy against leukemia cells, thereby providing a novel strategy for AgNPs in leukemia therapy.”
Induction of Apoptosis in Cancer Cells at Low Silver Nanoparticle Concentrations using Chitosan Nanocarrier
In this clinical study, published in the journal ACS Applied Material & Interfaces in January 2011, researchers used a chitosan-based carrier to deliver silver nanoparticles to human colon cancer cells. According to the study authors, “Cell viability assay demonstrated that the concentration of Ag NPs required to reduce the viability of HT 29 cells by 50% was 0.33 µg mL-1, much less than in previously reported data.” In other words, the researchers found that it only took a concentration of 3.3 ppm silver nanoparticles to reduce cancer cells by 50% in vitro. The researchers further stated, “The increased production of intracellular ROS due to Ag-CS NCs treatment indicated that the oxidative stress could augment the induction of apoptosis in HT 29 cells in addition to classical caspase signaling pathway. The use of significantly low concentration of Ag NPs impregnated in chitosan nanocarrier is a much superior approach in comparison to the use of free Ag NPs in cancer therapy.” In other words, the silver nanoparticles induced reactive oxygen species inside the cancer cells, resulting in an activation of the cellular signaling pathway that controls apopotosis (cellular suicide), and thereby triggering the cancer cells to self-destruct.
Cytotoxicity and ROS Production of Manufactured Silver Nanoparticles of Different Sizes in Hepatoma and Leukemia Cells
In this clinical study, published in the Journal of Applied Toxicology in November 2013, the researchers set out to investigate how AgNPs of different sizes interact with two different tumoral human cell lines, i.e., hepatoma [HepG2] and leukemia [HL-60], i.e., liver cancer cells and blood cancer cells. Using silver nanoparticles of 4.7 nm and 42 nm in size, respectively, the researchers discovered that the smaller silver nanoparticles had the most cytotoxic effect against the cancer cells. What’s more, the researchers found that the liver cancer cells were more sensitive to the silver nanoparticles than the leukemia cells, although the silver proved to be cytotoxic to both types of cancer cells.
Cytotoxic, Apoptotic Efficacy Of Silver Nanoparticles Synthesized From Indigofera Aspalathoids
In this clinical study, published in the International Journal of Pharmacy and Pharmaceutical Sciences in 2014 (Vol. 6, Issue 8), researchers studied the effects of silver nanoparticles on hepatocellular carcinoma cell line Hep3B, i.e., a liver cancer cell line. The cancer cells were exposed to 0 to 1,000 ppm of silver nanoparticles for 72 hours. Researchers noted significant cancer cell death, and found that the silver nanoparticles induced cell death in a dose-dependent manner, i.e., the higher the dose, the greater the toxic effect on the cancer cells. Cellular self-destruction began after 24 hours of incubation with silver nanoparticles, which “induced nucleosomal DNA fragmentation of Hep3B cells,” causing cell death. The researchers also noted that “The cytotoxic effects of silver are the result of active physicochemical interaction of silver atoms with the functional groups of intracellular proteins, as well as with the nitrogen bases and phosphate groups in DNA.” They went on to state that the silver nanoparticles “exhibited a significant cytotoxic effect on HEp 3B cell lines in vitro through induction of apoptosis and by inhibiting cell proliferation and angiogenesis.” Finally, the researchers concluded, “Our data suggest that silver nanoparticles…can induce cytotoxic effects on Hep3B cells, inhibiting tumor succession and thereby effectively controlling disease progression without toxicity to normal cells and these agents an effective alternative in tumor and angiogenesis-related diseases.”
Cytotoxic Activity of Highly Purified Silver Nanoparticles Sol Against Cells of Human Immune System
In this clinical study, published in the journal Applied Biochemistry and Biotechnology in April 2015, researchers found that when human promyelocytic leukemia cells (HL-60) and “human monocyte cells” (U-937) from a lymphoma cancer cell line were exposed to silver nanoparticles of 25 ppm concentration, the “viability of HL-60 cells (i.e., leukemia cells) diminished to about 60 % in the presence of AgN at concentration of 25 mg/l regardless of the length of the exposure time. At the same silver sol concentration, viability of U-937 cells decreased to about 70 % after 24 and 48 hours and to about 20% after 72 hours.” In other words, the ability of the cancer cells to maintain their life spans were significantly reduced after application of the silver nanoparticles. The researchers concluded that, “…nanosilver particles may be considered as a support for anticancer therapy.”
Synthesis and in vitro Antineoplastic Evaluation of Silver Nanoparticles Mediated by Agrimoniae herba Extract
In this clinical study, published in the International Journal of Nanomedicine in April 2014, researchers tested bare silver nanoparticles and specially prepared silver nanoparticles (i.e., silver nanoparticles conjugated with an herbal extract) against a human lung cancer cell line (A549), and found that both types of silver nanoparticles were toxic to the cancer cells. The researchers wrote that both bare silver nanoparticles and their specially prepared silver nanoparticles, “exhibited evident cytotoxicity against A549 cells, suggesting that AgNPs, as a drug carrier, also can act as an effective anticancer agent.” The researchers stated their specially prepared silver nanoparticles, “…displayed significantly higher antiproliferative effect against a human lung carcinoma cell line (A549 cells) than the bare silver nanoparticles.” The researchers concluded, “Malignant tumors are fatal diseases that threaten human health. Therefore, tremendous efforts have been put into exploring effective therapeutic modalities for antitumor treatment…this study suggests that AH-AgNPs exhibit the potential to be a promising drug-delivery system in antitumor therapy.”
Cytotoxicity of Biologically Synthesized Silver Nanoparticles in MDA-MB-231 Human Breast Cancer Cells
In this clinical study, published in the journal BioMedical Research International in 2013, researchers set out to evaluable the toxicity of silver nanoparticles against human breast cancer cells (MDA-MB-231). The researchers treated the breast cancer cells with concentrations of 5 ppm to 25 ppm silver nanoparticles for 24 hours. According to the researchers, “Breast cancer is the second most common cause of cancer death in women…We found that AgNPs inhibited the growth [of the breast cancer cells] in a dose-dependent manner… eventually leading to induction of apoptosis.” In other words, the silver nanoparticles caused the breast cancer cells to self-destruct. And the higher concentrations (25 ppm) worked better than the lower concentrations (5 ppm). The researchers concluded “The present results showed that AgNPs might be a potential alternative agent for human breast cancer therapy.”
Green Synthesis of Silver Nanoparticles Using Ganoderma neo-japonicum Imazeki: a Potential Cytotoxic Agent Against Breast Cancer Cells
In this clinical study, published in the International Journal of Nanomedicine in November 2013, researchers used specially prepared silver nanoparticles against breast cancer cells (MDA-MB-231). They found that treatment of the cancer cells with 1 ppm to 10 ppm silver nanoparticles for 24 hours caused “inhibition of cell viability” and “induction of membrane leakage” (i.e., the cancer cells started leaking and could no longer stay alive). The higher the dosage of silver nanoparticles, the greater the effect against the breast cancer cells. According to the researchers, “The results indicate that AgNPs possess cytotoxic effects with apoptotic features.” In other words, the silver caused the cancer cells to self-destruct. The researchers further wrote, “…the reactive oxygen species generated by AgNPs have a significant role in apoptosis.” In other words, it appears to be the ability of the silver to generate reactive oxygen species inside the cancer cells that ultimately results in cell death. The researchers concluded, “The present findings suggest that AgNPs could contribute to the development of a suitable anticancer drug, which may lead to the development of a novel nanomedicine for the treatment of cancers.”
Exposure to Silver Nanoparticles Induces Size- and Dose-dependent Oxidative Stress and Cytotoxicity in Human Colon Carcinoma Cells
In this clinical study, published in the journal Toxicology In Vitro in July 2014, clinical researchers set out to evaluate the effects of silver nanoparticles against human colon cancer cells. The researchers tested “the size-dependent effects of AgNPs by treating the human LoVo cell line, an intestinal epithelium model, with spherical AgNPs of well-defined sizes (10, 20, 40, 60 and 100nm).” In other words, they decided to test silver particles of five different particle sizes against colon cancer cells. Results: The smaller the silver particles were, the more effectively they penetrated the cancer cells, resulting in “the stimulation of a signaling cascade that generated ROS and inflammatory markers, leading to mitochondrial dysfunction and subsequently inducing apoptosis.” In other words, the smallest silver particles caused the colon cancer cells to self-destruct, whereas the largest of the silver particles (100 nm) could not even penetrate the cancer cells.
Comparative Cytotoxicity Of Nanosilver In Human Liver Hepg2 And Colon Caco2 Cells In Culture
In this clinical study, published in the Journal of Applied Technology in February 2014, the researchers treated human liver HepG2 cells (i.e., liver cancer cells) and human colon Caco2 cells (i.e., colorectal cancer cells) with silver nanoparticles with an average size of 20.4 nm in order to evaluate their toxicity to the cells. The researchers found significant toxicity to both cancer cell lines, but at different concentrations, with the colorectal cancer cells requiring a concentration of silver nanoparticles 10 times higher than the liver cancer cells. Interestingly, this was not a silver v/s cancer study, per se. The researchers simply used the two different lines of cancer cells to evaluate silver’s toxicity to cells in general. I’ve long argued against this approach, because it appears silver has a special affinity for cancer cells (and would therefore be more toxic to them), and because previous studies have demonstrated silver to be toxic to cancer cells without causing harm (relatively speaking) to surrounding healthy cells. In this case, the researchers actually concluded this to be the case, stating, “The HepG2 and Caco2 cells used this study appear to be targets for silver nanoparticles. The results of this study suggest that the differences in the mechanisms of toxicity induced by nanosilver may be largely as a consequence of the type of cells used. This differential rather than universal response of different cell types exposed to nanoparticles may play an important role in the mechanism of their toxicity.” In other words, cancer cells appear to be far more sensitive to the cytotoxic effects of silver nanoparticles, with some being even more sensitive to others.
Anti-leukemia Activity of PVP-coated Silver Nanoparticles via Generation of Reactive Oxygen Species and Release of Silver Ions
This clinical study, published in the journal Biomaterials in October 2013, was specifically designed to determine whether or not exposure to silver nanoparticles would “inhibit the grown of acute myeloid leukemia (AML) cells,” and thus represent a viable potential treatment for leukemia (i.e., cancer of the blood and bone marrow). According to the study authors, “We found that silver nanoparticles could inhibit the viability of AML cells including isolates from AML patients.” The researchers also found that the “silver nanoparticles caused the production of reactive oxygen species (ROS), losses of mitochondrial membrane potential, DNA damage and apoptosis” in the leukemia cells. In other words, the silver nanoparticles caused the leukemia cells to self-destruct. What’s more, the researchers found that, “Similar results were obtained when cells were treated with silver ions alone.” The researchers concluded, “…these data supported the model that both generation of ROS and release of silver ions played critical roles in the silver nanoparticle-induced cytotoxic effect against AML cells. Taken together, this work elucidated the cytotoxic effect of silver nanoparticles on AML cells and their underlying mechanism and might have significant impact on AML treatment.” In other words, the results indicate silver nanoparticles could eventually prove to be an effective leukemia treatment.
Differential Cytotoxic And Radiosensitizing Effects Of Silver Nanoparticles On Triple-Negative Breast Cancer And Non-Triple-Negative Breast Cells
In this clinical study, published in the International Journal of Nanomedicine in June 2015, researchers demonstrated that silver nanoparticles were highly toxic to triple-negative breast cancer cells (TNBC) “at doses that have little effect on non-tumorigenic breast cells or cells derived from liver, kidney, and monocyte lineages.” In other words, the silver nanoparticles caused toxicity and ultimately cell death in the breast cancer cells, at levels that caused no harm to normal healthy human breast cells, nor to cells involved in the clearance of silver from the body, such as liver and kidney cells, nor to immune cells (i.e., monocytes). According to the study authors, compared to other types of breast tumors, triple-negative breast cancer “has a greater likelihood of metastasis, and the 5-year survival rate of women diagnosed with TNBC is markedly decreased.” Therefore, the researchers argued, “there’s a pressing need for effective therapeutics to treat this form of breast cancer.” The researchers concluded, “… we find that AgNPs are cytotoxic to TNBC cells at doses that have little effect on noncancerous breast cells or other healthy cells.”
Biogenic Silver Nanoparticles For Cancer Treatment: An Experimental Report
In this clinical study, published in the journal Colloids and Surfaces B Biointerfaces in June 2013, researchers investigated the in vitro toxicity of silver nanoparticles on the MCF-7 breast cancer cell line. The silver nanoparticles were synthesized using a leaf extract (Sesbania grandiflora), and were 22 nm in size, with some agglomeration of particles. According to the study authors, the silver nanoparticles were cytotoxic to the breast cancer cells, producing gradual apoptosis (cellular self-destruction). The researchers wrote, “It was surprising that biogenic silver nanoparticles showed cytotoxic effect against MCF-7 cell lines… This may be a first report on anti-MCF-7 property of biogenic AgNPs… It is necessary to study the formulation and clinical trials to establish the nano drug to treat cancer cells.”
The Cellular Uptake And Cytotoxic Effect Of Silver Nanoparticles On Chronic Myeloid Leukemia Cells
In this clinical study, published in the Journal of Biomedical Nanotechnology, researchers began by saying, “Several studies have suggested that silver nanoparticles (AgNPs) have the potential to treat human cancers, including leukemia.” The researchers went on to state that they wanted to study the cellular mechanisms through which “silver nanoparticles inhibit the growth of leukemic cells.” They found that silver nanoparticles enter leukemic cells and locate in endosomes, which are membrane-bound vesicles found in the cytoplasm of virtually every human and animal cell. Once inside the leukemic cell, the silver nanoparticles triggered the generation of reactive oxygen species, causing “cytotoxicity and apoptosis.” In other words, the leukemic cancer cells self-destructed. The researchers concluded, “These results suggested that proper usage of silver nanoparticles would be of great significance for chronic myeloid leukemia (CML) treatment in future.”
Silver Nanoparticles Impregnated Alginate-Chitosan-Blended Nanocarrier Induces Apoptosis In Human Glioblastoma Cells
In this clinical study, published in the journal Advanced Healthcare Materials in January 2014, researchers coated silver nanoparticles with an alginate/chitosan blend, and then treated human glioblastoma (i.e., malignant brain cancer) cells with them. Using a concentration of 24 ppm silver nanoparticles, the researchers witnessed an “anticell proliferative effect,” meaning, of course, that the brain cancer cells were no longer able to multiply. The researchers noted extensive DNA damage to the cancer cells, followed by apoptosis (cellular self-destruction), which they attributed to an elevation in reactive oxygen species caused by the silver. The researchers concluded that being able to use their specially prepared silver nanoparticles at such low doses “makes it a promising tool for cancer therapy.”
Cytotoxic Effect And Apoptosis Induction By Silver Nanoparticles In Hela Cells
In this clinical study, published in the journal Biochemical and Biophysical Research Communications in December 2009, researchers tested silver nanoparticles on HeLa cells (cervical cancer cells) to determine their biological effects. According to the researchers, “We observed the cytotoxic effect of nanosilver in HeLa cells.” They attributed the cell toxicity of the nanosilver to oxidative stress resulting in apoptosis (i.e., cellular self-destruction). The researchers noted that while the nanosilver’s cytotoxic effect was lower than they’d seen with silver ions, it was nevertheless significant. [This was not a silver v/s cancer study, per se, as the researchers were actually trying to demonstrate silver’s toxicity to cells in general – a mistaken approach, in my opinion, since previous studies have demonstrated silver’s ability to destroy cancer cells without harming surrounding healthy cells. Therefore, while the study does prove silver to be an effective trigger for the destruction of cervical cancer cells, its relevance to silver’s effect on normal, healthy human cells is certainly debatable.]
Biogenic Silver Nanoparticles From Abutilon Indicum: Their Antioxidant, Antibacterial And Cytotoxic Effects In Vitro
In this clinical study, published in the journal Colloids and Surfaces B Biointerfaces in April 2015, researchers used silver nanoparticles synthesized with Abutilon indicum leaf extract and evaluated their biological effects on human colon cancer cells (COLO 205). They found that concentrations of only 3 and 4 ppm silver nanoparticles resulted in DNA fragmentation and eventual apoptosis (i.e., cellular self-destruction) to half the colon cancer cells after only 24 hours and 48 hours respectively.
Silver Nanoparticles Induce Toxicity In A549 Cells Via ROS-Dependent And ROS-Independent Pathways
In this clinical study, published in the journal Toxicology In Vitro in February 2013, researchers exposed a lung cancer cell line (i.e., adenocarcinomic human alveolar basal epithelial cells) to silver nanoparticles in order to study the toxicity in relation to the generation of reactive oxygen species (ROS). According to the study authors, the silver nanoparticles caused formation of reactive oxygen species inside the cancer cells, resulting in a “reduction of cell viability and mitochondrial membrane potential” as well as “an increase in the proportion of cells in the apoptosis population.” In other words, as other clinical studies have demonstrated, the silver caused the cancer cells to gradually self-destruct. This was another study that was not a “silver v/s cancer” study, per se. The researchers appear to have simply selected the lung cancer cell line (A549) to study the toxic effects of silver on lung cells in general, which is something I’ve long advised against, since silver seems to have an affinity for cancer cells and therefore are not a good model for determining silver’s potential toxic effects against normal human cells. Nevertheless, the researchers demonstrated silver’s ability to cause lung cancer cells to self-destruct.
Silver Nanoparticles: Anti-Bacterial and in vitro Cytotoxic Activity
In this clinical study, published in the International Journal of Biological, Ecological and Environmental Sciences in 2013, researchers “aimed to evaluate the anti-bacterial and anti-cancer properties of the silver nanoparticles synthesized using the macro algae-Gelidiella sp.” Using colon cancer cells (HT29), the authors found remarkable anti-cancer activity when the silver nanoparticles were applied. According to the study authors, “The potency of silver nanoparticles to inhibit the cancerous growth was recorded in terms of decrease in viable cell count as compared to the control value. The inhibition of the growth of the human colon cell line (HT 29) has been found to be dose dependent…” Using concentrations ranging from a high of 1,000 ppm to a low of 3.90 ppm, the researchers found that “the presence of 31.25 ppm of silver nanoparticles significantly inhibited the cancer cell line’s growth.”
Potential Of Colloidal Or Silver Nanoparticles To Reduce The Growth Of B16F10 Melanoma Tumors
In this clinical study, published in the African Journal of Microbiology Research in March 2013, the researchers noted, “Previously, we reported the cytotoxic effect of colloidal silver on MCF-7 breast cancer cell line. However, there is scarce information on its antitumor potential. The aim of this study was to evaluate the anti-tumoral activity of colloidal silver or silver nanoparticles in a B16F10 melanoma mice model.” In other words, they induced skin cancer tumors in mice, and then treated them with differing concentrations of colloidal silver and silver nanoparticles. First, they tested both colloidal silver and silver nanoparticles in vitro (i.e., in the test tube) and found them to be effective at stopping the spread of melanoma cancer cells. Then, they tested both colloidal silver and silver nanoparticles on mice in which melanoma cancer tumors had been induced. They found that by injecting the silver subcutaneously (i.e., under the skin) “melanoma tumor growth was significantly decreased.” The researchers concluded, “Our results suggest that colloidal silver or silver nanoparticles could be useful as an antiproliferative drug, inducing an impairment of tumoral growth.” In other words, both colloidal silver and silver nanoparticles were found to impair the growth of melanoma tumors.
Antibacterial and Anticancer Activity of Silver Nanoparticles Synthesized from Cynodon dactylon Leaf Extract
In this clinical study, published in the Journal of Academia and Industrial Research (JAIR) in May 2015, researchers synthesized silver nanoparticles using Cynodon dactylon leaf extract, and then tested it against the HEpG-2 line of liver cancer cells, as well as against pathogenic microbes such as against Escherichia coli, Staphylococcus aureus, Micrococcus lutues and Salmonella typhimurium. Not only did the silver nanoparticles kill the pathogens, but in the cancer cells study they “showed dose-dependent cytotoxicity against HEpG-2 cells.” In other words, cancer cell life decreased proportionate to the concentration of silver being applied, with 1,000 ppm silver nanoparticles reducing cell viability by an astonishing 80% whereas 15.6 ppm silver nanoparticles reduced cell viability by only 11%. The researchers concluded, “Biosynthesized silver nanoparticles showed excellent antimicrobial activity and possessed considerable cytotoxic effect against HEpG-2…further studies are needed to fully characterize the toxicity and the mechanisms involved with the antimicrobial and anticancer activity of these particles.”
Colloidal Silver And Chitosan Stabilized Silver Nanoparticles On Mcf-7 And Hepg2
In this clinical study, published in the European Journal of Biomedical and Pharmaceutical Sciences, researchers tested the anti-cancer properties of colloidal silver and silver nanoparticles stabilized by chitosan. According to the study authors, “The present study was aimed to investigate the in vitro cytotoxicity effect of colloidal silver and chitosan stabilized silver nanoparticles against human breast cancer cells (MCF-7) and liver cancer cells (HepG2) towards the development of anticancer drugs.” Results: The silver treatments demonstrated “cytotoxic effect against MCF-7 and HepG2 cell lines.” The study authors concluded, “There was an immediate induction of cellular damage in terms of loss of cell membrane integrity, oxidative stress and apoptosis were found in the cell which treated with colloidal silver and chitosan stabilized silver nanoparticles.” In other words, both forms of silver caused liver and breast cancer cells to self-destruct.
Anticancer Activity of Silver Nanoparticles Synthesized by the Seaweed Ulva lactuca Invitro
In this clinical study, published in the journal Open Access Scientific Reports in 2012, researchers tested silver nanoparticles against three different human cancer cell lines, i.e., laryngeal cancer cells (Hep2), breast cancer cells (MCF 7) and colon cancer cells (HT29). The researchers found the silver nanoparticles to be effective against all three cancer cell lines in test tube studies, without causing toxicity to normal cells. The researchers concluded, “The synthesized nanoparticles were potently cytotoxic against Hep 2 cell lines and mildly cytotoxic against MCF 7 and HT 29 cell lines… Cytotoxic effect is inversely proportional to the size of the bioactive compound AgNP.” In other words, the smaller the silver nanoparticles used, the greater the anti-cancer benefit documented.
Effect of Silver Nanoparticles on Common Bacteria in Hospital Surfaces
In this clinical study, published in June 2013 and titled “Effect of Silver Nanoparticles on Common Bacteria in Hospital Surfaces,” researchers from the Infectious and Tropical Diseases Research Center, University of Medical Sciences, Ahvaz, Iran, tested three different concentrations of silver nanoparticles – 100 ppm, 200 ppm and 300 ppm -- on surface colonies of infectious microbes including MRSA, Pseudomonas aeuroginosa and Bacillus cereus. According to the study authors, each of the three dilutions of silver nanoparticles were able to produce “more than a 99 percent reduction” in bacterial surface contamination. While it took longer for the more dilute preparations to work, there were “no remarkable differences” between the three “when tested at 5,15, 30 and 60 minute disinfection intervals.” The researchers concluded: “Silver nanoparticles had appropriate effects in all three types of dilutions…After five minutes all disinfectants reduced the S. aureus colony count significantly (more than 99%), but none of them could bring the S. aureus colony count to zero. This rate was achieved following 30 minutes of disinfection with 300 ppm silver nanoparticles…For two other dilutions of silver nanoparticles, this rate was possible after 60 minutes of disinfection.” In short, whereas other clinical studies have demonstrated lower concentrations of silver nanoparticles to reduce bacterial count on hospital surfaces to zero after 24 to 48 hours, this study demonstrated that concentrations of 100 ppm, 200 ppm and 300 ppm silver nanoparticles could reduce the bacterial count by 99% after just five minutes of application, with a full 100% reduction in bacterial count being achieved within 30 minutes when using the 300 ppm nanosilver, and after one hour when using the 100 ppm and 200 ppm nanosilver.

More documents to come, so keep checking back...

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