In this December 2015 clinical study published in the Journal of Nanobiotechnology, researchers demonstrated silver nanoparticles have a potent inhibitory effect on biofilm formation in the Candida albicans species of fungal pathogen. The researchers wrote, “Candida albicans is the most common pathogenic fungus isolated in bloodstream infections in hospitalized patients, and the fourth most frequent infection in U.S. hospitals.” They also noted that Candida albicans “has the ability to form biofilms — a community of fungal cells surrounded by a protective matrix that effectively shelters Candida against the action of antifungal drugs.” Because of its ability to form protective biofilms, Candida can be extremely difficult to eradicate with modern antifungal drugs. The researchers decided to test silver nanoparticles to see if they could defeat the biofilm formation of the Candida fungal species, and could therefore be used as an alternative to prescription antifungal drugs. The study authors concluded, “Our results demonstrate that silver nanoparticles are potent inhibitors of C. albicans biofilm formation. Observations with a Scanning Electron Microscope are consistent with an overall loss of structure of biofilms mostly due to disruption of the outer cell membrane/wall and inhibition of filamentation. Transition Electron Microscopy indicates the permeabilization of the cell wall and subsequent disruption of the structural layers of the outer fungal cell wall. The anti-biofilm effects are via cell wall disruption.” In other words, the silver nanoparticles not only inhibited the formation of Candida biofilms, but they also destroyed existing biofilms by disrupting the outer cell wall of the fungus and entering into the fungal cells.

In this clinical study, titled “Size- and Shape-dependent Clinical and Mycological Efficacy of Silver Nanoparticles on Dandruff,” published in the International Journal of Nanomedicine in June, 2015, researchers from India found that silver nanoparticles of various shapes and sizes were effective against the Malassezia furfur fungus, which causes dandruff. According to the researchers, “The present work outlines a detailed analysis of the treatment of scalp infection using silver nanomaterials (Ag NMs), and focuses on biocidal activity owing to manipulation of size, shape, and structure…silver nanomaterials demonstrated enhanced biocidal tendencies compared to market available drugs, itracanozole and ketoconazole, showing greater zones of inhibition.” So the tiny, 20 nm silver nanoparticles worked even better against the fungus than prescription dandruff drugs such as itracanozole and ketoconazole. The researchers even tested the silver nanoparticles in vivo, using the rat model. They wrote, “An in vivo model for M. furfur infection was generated by passing fungi subcutaneously in rats’ skin. Again, 20 nm particles showed best normalization of skin after 10 days on regular dosing.” So the dandruff-causing fungal infection of the skin was cured after only 10 days of use. Finally, the researchers found that the silver nanoparticles caused no damage to the skin, whatsoever. They wrote, “The results of skin irritation test indicate that Ag NPs do not produce any dermatological reaction and were well tolerated by rats showing no drastic visual flakes formation and inflammation.” Instead, the researchers found that the silver nanoparticle treatment brought about significant tissue repair. They wrote, “Biochemical analysis performed by checking antioxidant enzymatic activities indicated tissue repair and normalization of enzymes and protein concentration by Ag NPs.” The researchers concluded that the silver nanoparticles were “found to be superior to tested drugs” and that “Small-sized spherical Ag NPs can be used as an important cost-effective fungistatic agent in formulations for treating scalp problems, since they can be produced in larger quantities and very small amount is required for the desired effect.”

In this clinical study, published in 2008 in the journal Nanoscale Research Letters, researchers tested several forms of antimicrobial silver against the Monkeypox virus Zaire strain, which was originally obtained from a fatally infected human in Zaire and shown to be fatal in monkeys, as well. The virus was tested under biosafety level 3 conditions in order to prevent infection of the researchers. In this study, researchers used what’s called a “plaque reduction assay test” in order to determine whether or not the addition of nanosilver to viral-infected cells being grown in Petri dishes would decrease the rate of viral replication (in terms of plaque formation) in the cells, thus demonstrating reduced infectivity of the virus. According to the researchers, various concentrations of silver nanoparticles of 10 nm size significantly reduced Monkeypox viral plaque formation. They wrote: “…our results indicate that the silver-containing nanoparticles with a diameter of approximately 10 nm (Ag-PS-10) were the most effective at inhibiting Monkeypox virus infectivity as demonstrated by the statistically significant reduction in Monkeypox virus plaque formation at all concentrations tested.” The researchers concluded, “These results demonstrate that silver-based nanoparticles of approximately 10 nm inhibit Monkeypox virus infection in vitro, supporting their potential use as an anti-viral therapeutic.” Here we see clinical researchers noting that the ability of silver to reduce Monkeypox viral infectivity supports the idea that silver has potential as an effective anti-viral therapy.

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.

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.

In this clinical study, titled “Effects of green-synthesized silver nanoparticles on lung cancer cells in vitro and grown as xenograft tumors in vivo,” published in May 2016 in the International Journal of Nanomedicine, cancer researchers from Rutgers State University of New Jersey and the Guandong University of Technology in China combined forces to test silver nanoparticles against lung cancer cells in vitro and in vivo. For the in vivo (i.e., live animal) testing, the researchers used immunodeficient mice into which lung cancer tumor was grafted. The researchers wrote: “Unlike other metal nanoparticles, AgNPs are nontoxic to human body at a lower dosage…the applications of AgNPs have increased in cancer diagnosis and treatment, not only as attractive targeted drug delivery vehicles or probes for early cancer screening, but also as a promising therapeutic molecule by itself. [In previous studies] AgNPs have shown potential cytotoxicity against various cancer cells such as lung cancer A549 cells, breast cancer MCF-7 cells, colon cancer HT29 cells, cervical cancer HeLa cells, and Dalton’s lymphoma ascites tumor…The present study was designed to explore the anticancer activities of our green-synthesized AgNPs in vitro and in vivo. These results further provide new approaches for treating lung cancer and other types of cancers by using silver-based nanoparticle therapies…AgNPs significantly suppressed the H1299 tumor growth in a xenograft severe combined immunodeficient (SCID) mouse model. The results demonstrate the anticancer activities of AgNPs, suggesting that they may act as potential beneficial molecules in lung cancer chemoprevention and chemotherapy, especially for early-stage intervention…Approximately, 50% of H1299 cells died when treated with AgNPs at the concentrations between 5 and 8 µg/mL.” In other words, not only did the silver nanoparticles suppress the tumor growth in the immunodeficient mice, causing tumor growth to slow dramatically as cancer cells died, but also a full 50% of the cancer cells tested in vitro (test tube) were killed at very low concentrations of silver (i.e., 8 ppm).

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.

In this clinical study, published in the journal Nanotoxicology in June 2016, researchers demonstrated that oral administration of silver nanoparticles capped with PVP or Citrate had negligible effect on gut bacteria in the murine (mouse) model — the implication being that silver nanoparticles delivered orally either through unintentional contact with consumer products, or through dietary supplementation, or as a substitute for antibiotics in animal feed would not harm beneficial digestive microbes. The researchers wrote, “We evaluated murine gut microbial communities using culture-independent sequencing of 16S rRNA gene fragments following 28 days of repeated oral dosing of well-characterized AgNPs of two different sizes (20 and 110?nm) and coatings (PVP and Citrate). Irrespective of size or coating, oral administration of AgNPs at 10?mg/kg body weight/day did not alter the membership, structure or diversity of the murine gut microbiome. Thus, in contrast to effects of broad-spectrum antibiotics, repeat dosing of AgNP, at doses equivalent to 2000 times the oral reference dose and 100-400 times the effective in vitro anti-microbial concentration, does not affect the indigenous murine gut microbiome.”

In this study, published in the International Journal of Nanomedicine, November 2015, researchers concluded that silver nanoparticles “exhibited an excellent antibacterial activity against Methicillin-Resistant S. aureus (MRSA), Acinetobacter baumannii, Enterococcus faecalis, and Escherichia coli.” The researchers state that 100% of the MRSA cells were inactivated after 4 hours of exposure to the silver nanoparticles which were embedded in a graphite oxide matrix. “In addition,” the researchers stated, “no toxicity was found within the tested concentration range” for either the graphite oxide or the silver nanoparticles. The researchers concluded, “Our results indicate that the graphite oxide silver nanocomposite is a promising antibacterial agent against common nosocomial bacteria, particularly antibiotic-resistant MRSA.”

Two separate research studies tested nanosilver-impregnated X-Static brand fabric from Noble Fiber Technologies, Inc. as a means of reducing household infestations of dust mites. In the first study, conducted by researchers in Seoul, Korea, in 2003, a 99.9% reduction in the infestation of dust mites (i.e., Dermatophagoides farinae and Dermatophagoides pteronyssinus) was achieved within 48 hours after a population of dust mites were placed on the silver-impregnated fabric in an enclosed test tube setting. In the second study, conducted by researchers in France in 2003, a 94% reduction in house dust mite (i.e., Dermatophagoides pteronyssinus) populations was achieved in a different test designed to document the fate of the mites through two developmental cycles (six weeks). In both studies, treated samples were tested against untreated samples in which there were no correspondingly similar reductions in dust mite populations. The Seoul, Korea researchers also tested the silver-impregnated fabric against populations of Staphylococcus aureus and Klebsiella pneumonia bacterial pathogens and achieved a 99.9% reduction in bacterial populations.

In a brand new clinical study published in the journal Nanomedicine: Nanotechnology, Biology and Medicine, titled “Silver nanoparticles modulate abc transporter activity and enhance chemotherapy in multidrug resistant cancer,” clinical researchers demonstrated silver nanoparticles to also be effective against cancers that are resistant to multiple types of chemotherapy drugs. According to the study’s authors, “The emergence of multidrug resistant (MDR) cancer phenotypes dramatically attenuates the efficiency of antineoplastic drug treatments often leading to the failure of chemotherapy. Therefore there is an urgent need to engineer new therapeutically useful agents and propose innovative approaches able to defeat resistant cancer cells. Although the remarkable anti-cancer features of silver nanoparticles (AgNPs) have already been delineated their impact on multiple-drug-resistant cancer has never been investigated. Herein, we report that AgNPs have a notable anti-proliferative effect and induce apoptosis mediated cell death both in drug sensitive and in MDR cancer cells.” In other words, the researchers confirmed earlier studies demonstrating silver nanoparticles to stop malignant cancer cells from spreading, causing them to commit cellular suicide (i.e., apoptosis). What’s more, they discovered that silver nanoparticles also stop the spread of malignant cancer cells that are resistant to multiple chemotherapy drugs! The researchers went on to demonstrate that adding silver nanoparticles to six different existing cancer drugs dramatically improved the effectiveness of the drugs against drug-resistant cancer.

In this study, reprinted in September 2010 in the journal The Indian Practitioner: a Monthly Journal Devoted to Medicine, Surgery and Public Health, researchers demonstrated that Silver Sol, a brand of colloidal silver manufactured by American Biotech Labs, was able to remove the malaria parasite from the blood of 56 human subjects in an average of five days. At a concentration of only 10 ppm, the optimal dose was determined to be 15 ml twice a day. The fastest cure rate was found to be 2 days, and the most days required to achieve full recovery was found to be 10 days. According to the researchers, “Human subjects were found to have no malaria parasites in their blood (as determined by clinical microscopy) after an average of five days of Silver Sol treatment. No patients suffered any adverse side effects, while 100% were cured from Malaria in an average of five days. It is concluded that Silver Sol can be taken daily to completely eliminate the malaria parasite from the blood of malaria infected subjects in an average of five days.”