This section will be very much a work in progress. I have over 100 science articles to go through which will gradually be added to this section. You will find the full references at the end of this section for all the articles included here and in the Reference Section. The article by Lv and colleagues (2014) included below was the impetus for starting this site.
(Ahmadi, Abolghasemi, Parhizgari, & Moradpour, 2013)
Background: One of the most important causes of complications and mortality in medical centers are nosocomial infections. Disinfection of hospital surfaces is an essential element for ensuring that infectious agents are not transmitted to patients. Alcohol-based and chlorine-based disinfectants have unfavorable properties. Given that the antimicrobial effect of heavy metals such as silver is recognized as a viable option for eliminating bacteria, the exploration of nanotechnology in this context has been described in this study. Nanotechnology uses both science and technology to produce new materials with nano-scales.
Objectives: The effect of silver nanoparticles on some common hospital bacteria has been studied in this research.
Patients and Methods: We have selected nine patients’ metal file covers and following sterilizing, we have infected them with one of these bacteria; Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus cereus. Then, the infected surfaces have been disinfected with different dilutions of silver nanoparticles. Sampling and culturing has done following four specific intervals. Afterwards, the colonies that developed have been counted and compared.
Results: All of the three dilutions of silver nanoparticles could bring the colony count out of 7.5×106 to less than 100 which indicates more than a 99 percent reduction. No remarkable difference of the three dilutions of disinfectants was observed in reducing the colony count in 5,15, 30 and 60 minute disinfection intervals (P value > 0.05). The effect of constant dilution of silver nanoparticles on the reduction of organisms varied in response to the time of disinfection (P value < 0. 05). Conclusion: Silver nanoparticles had appropriate effects in all three types of dilutions and allowing for a more protracted contact time has given significantly better results.
(Baral, Dewar, & Connett, 2008)
In our case we have documented significant improvements in well-being that were temporally associated with the use of the drug. However, this is a single anecdote and caution should be used in interpreting the significance of these observations. If there was a direct clinical effect of the silver we speculate that this might have been as a result of a bactericidal action on CF pathogens, as suggested by the decreased occurrence of B. multivorans on sputum cultures. Researchers in Denmark have shown that silver is highly effective as a bactericidal agent against biofilm and planktonic models of Gram-negative organisms, including P. aeruginosa. Currently there is no evidence to support the use of silver products in CF but their potential benefits might be worthy of further exploration. An American study has shown benefits for silver in the treatment of Burkholderia dolosa infection in a murine model of severe lung sepsis. Further in vitro studies of the effects of silver on the organisms within CF sputa and a better understanding of safe dosaging are essential first steps in exploring the potential for this use of this treatment option.
(Castellano et al., 2007)
Wound dressings containing silver as antimicrobial agents are available in various forms and formulations; however, little is understood concerning their comparative efficacy as antimicrobial agents. Eight commercially available silver-containing dressings, Acticoat 7, Acticoat Moisture Control, Acticoat Absorbent, SilvercelTM, Aquacel Ag, Contreet F, Urgotol SSD and Actisorb, were tested to determine their comparative antimicrobial effectiveness in vitro and compared against three commercially available topical antimicrobial creams, a non treatment control, and a topical silver-containing antimicrobial gel, Silvasorb. Zone of inhibition and quantitative testing was performed by standard methods using Escherichia coli, Pseudomonas aeruginosa, Streptococcus faecalis and Staphylococcus aureus. Results showed all silver dressings and topical antimicrobials displayed antimicrobial activity. Silver-containing dressings with the highest concentrations of silver exhibited the strongest bacterial inhibitive properties. Concreet F and the Acticoat dressings tended to have greater antimicrobial activity than did the others. Topical antimicrobial creams, including silver sulfadiazine, Sulfamylon and gentamicin sulfate, and the topical antimicrobial gel Silvasorb exhibited superior bacterial inhibition and bactericidal properties, essentially eliminating all bacterial growth at 24 hours. Silver-containing dressings are likely to provide a barrier to and treatment for infection; however, their bactericidal and bacteriostatic properties are inferior to commonly used topical antimicrobial agents.
(Hadrup & Lam, 2014)
Orally administered silver has been described to be absorbed in a range of 0.4–18% in mammals with a human value of 18%. Based on findings in animals, silver seems to be distributed to all of the organs investigated, with the highest levels being observed in the intestine and stomach. In the skin, silver induces a blue–grey discoloration termed argyria. Excretion occurs via the bile and urine. The following dose dependent animal toxicity findings have been reported: death, weight loss, hypoactivity, altered neurotransmitter levels, altered liver enzymes, altered blood values, enlarged hearts and immunological effects. Substantial evidence exists suggesting that the effects induced by particulate silver are mediated via silver ions that are released from the particle surface. With the current data regarding toxicity and average human dietary exposure, a Margin of Safety calculation indicates at least a factor of five before a level of concern to the general population is reached.
(Lv et al., 2014)
Coronaviruses belong to the family Coronaviridae, which primarily cause infection of the upper respiratory and gastrointestinal tract of hosts. Transmissible gastroenteritis virus (TGEV) is an economically significant coronavirus that can cause severe diarrhea in pigs. Silver nanomaterials (Ag NMs) have attracted great interests in recent years due to their excellent anti-microorganism properties. Herein, four representative Ag NMs including spherical Ag nanoparticles (Ag NPs, NM-300), two kinds of silver nanowires (XFJ011) and silver colloids (XFJ04) were selected to study their inhibitory effect on TGEVinduced host cell infection in vitro. Ag NPs were uniformly distributed, with particle sizes less than 20 nm by characterization of environmental scanning electron microscope and transmission electron microscope. Two types of silver nanowires were 60 nm and 400 nm in diameter, respectively. The average diameter of the silver colloids was approximately 10 nm. TGEV infection induced the occurring of apoptosis in swine testicle (ST) cells, down-regulated the expression of Bcl-2, up-regulated the expression of Bax, altered mitochondrial membrane potential, activated p38 MAPK signal pathway, and increased expression of p53 as evidenced by immunofluorescence assays, real-time PCR, flow cytometry and Western blot. Under non-toxic concentrations, Ag NPs and silver nanowires significantly diminished the infectivity of TGEV in ST cells. Moreover, further results showed that Ag NPs and silver nanowires decreased the number of apoptotic cells induced by TGEV through regulating p38/mitochondria-caspase3 signaling pathway. Our data indicate that Ag NMs are effective in prevention of TGEV-mediated cell infection as a virucidal agent or as an inhibitor of viral entry and the present findings may provide new insights into antiviral therapy of coronaviruses.
(Montano et al., 2019)
Up until the first half of the 20th century, silver found significant employment in medical applications, particularly in the healing of open wounds, thanks to its antibacterial and antifungal properties. Wound repair is a complex and dynamic biological process regulated by several pathways that cooperate to restore tissue integrity and homeostasis. To facilitate healing, injuries need to be promptly treated. Recently, the interest in alternatives to antibiotics has been raised given the widespread phenomenon of antibiotic resistance. Among these alternatives, the use of silver appears to be a valid option, so a resurgence in its use has been recently observed. In particular, in contrast to ionic silver, colloidal silver, a suspension of metallic silver particles, shows antibacterial activity displaying less or no toxicity. However, the human health risks associated with exposure to silver nanoparticles (NP) appear to be conflicted, and some studies have suggested that it could be toxic in different cellular contexts. These potentially harmful effects of silver NPdepend on various parameters including NP size, which commonly range from 1 to 100 nm. In this study, we analyzed the effect of a colloidal silver preparation composed of very small and homogeneous nanoparticles of 0.62 nm size, smaller than those previously tested. We found no adverse effect on the cell proliferation of HaCaT cells, even at high NP concentration. Time-lapse microscopy and indirect immunofluorescence experiments demonstrated that this preparation of colloidal silver strongly increased cell migration, re-modeled the cytoskeleton, and caused recruitment of E-cadherin at cell-cell junctions of human cultured keratinocytes.
(Morones-Ramirez, Winkler, Spina, & Collins, 2013)
A declining pipeline of clinically useful antibiotics has made it imperative to develop more effective antimicrobial therapies, particularly against difficult-to-treat Gram-negative pathogens. Silver has been used as an antimicrobial since antiquity, yet its mechanism of action remains unclear. 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. We show both in vitro and in a mouse model of urinary tract infection that the ability of silver to induce oxidative stress can be harnessed to potentiate antibiotic activity. Additionally, we demonstrate in vitro and in two different mouse models of peritonitis that silver sensitizes Gram-negative bacteria to the Gram-positive–specific antibiotic vancomycin, thereby expanding the antibacterial spectrum of this drug. Finally, we used silver and antibiotic combinations in vitro to eradicate bacterial persister cells, and show both in vitro and in a mouse biofilm infection model that silver can enhance antibacterial action against bacteria that produce biofilms. This work shows that silver can be used to enhance the action of existing antibiotics against Gram-negative bacteria, thus strengthening the antibiotic arsenal for fighting bacterial infections.
(Rogers, Parkinson, Choi, Speshock, & Hussain, 2008)
The use of nanotechnology and nanomaterials in medical research is growing. Silver-containing nanoparticles have previously demonstrated antimicrobial efficacy against bacteria and viral particles. This preliminary study utilized an in vitro approach to evaluate the ability of silver-based nanoparticles to inhibit infectivity of the biological select agent, monkeypox virus (MPV). Nanoparticles (10–80 nm, with or without polysaccharide coating), or silver nitrate (AgNO3) at concentrations of 100, 50, 25, and 12.5 lg/mL were evaluated for efficacy using a plaque reduction assay. Both Ag-PS-25 (polysaccharide-coated, 25 nm) and Ag-NP-55 (non-coated, 55 nm) exhibited a significant (P B 0.05) dose-dependent effect of test compound concentration on the mean number of plaque-forming units (PFU). All concentrations of silver nitrate (except 100 lg/mL) and Ag-PS-10 promoted significant (P B 0.05) decreases in the number of observed PFU compared to untreated controls. Some nanoparticle treatments led to increased MPV PFU ranging from 1.04to 1.8-fold above controls. No cytotoxicity (Vero cell monolayer sloughing) was caused by any test compound, except 100 lg/mL AgNO3. These results demonstrate that silver-based nanoparticles of approximately 10 nm inhibit MPV infection in vitro, supporting their potential use as an anti-viral therapeutic.
(Sim, Barnard, Blaskovich, & Ziora, 2018)
The use of silver to control infections was common in ancient civilizations. In recent years, this material has resurfaced as a therapeutic option due to the increasing prevalence of bacterial resistance to antimicrobials. This renewed interest has prompted researchers to investigate how the antimicrobial properties of silver might be enhanced, thus broadening the possibilities for antimicrobial applications. This review presents a compilation of patented products utilizing any forms of silver for its bactericidal actions in the decade 2007–2017. It analyses the trends in patent applications related to different forms of silver and their use for antimicrobial purposes. Based on the retrospective view of registered patents, statements of prognosis are also presented with a view to heightening awareness of potential industrial and health care applications.
Ahmadi, F., Abolghasemi, S., Parhizgari, N., & Moradpour, F. (2013). Effect of Silver Nanoparticles on Common Bacteria in Hospital Surfaces. Jundishapur J Microbiol, 6(3), 209-214. doi:10.5812/jjm.4585
Baral, V., Dewar, A., & Connett, G. (2008). Colloidal silver for lung disease in cystic fibrosis. Journal of the Royal Society of Medicine, 101(1_suppl), 51-52. doi:10.1258/jrsm.2008.s18012
Castellano, J. J., Shafii, S. M., Ko, F., Donate, G., Wright, T. E., Mannari, R. J., . . . Robson, M. C. (2007). Comparative evaluation of silver-containing antimicrobial dressings and drugs. International Wound Journal, 4(2), 114-122.
Hadrup, N., & Lam, H. R. (2014). Oral toxicity of silver ions, silver nanoparticles and colloidal silver – A review. Regulatory Toxicology and Pharmacology, 68(1), 1-7. doi:https://doi.org/10.1016/j.yrtph.2013.11.002
Lv, X., Wang, P., Bai, R., Cong, Y., Suo, S., Ren, X., & Chen, C. (2014). Inhibitory effect of silver nanomaterials on transmissible virus-induced host cell infections. Biomaterials, 35(13), 4195-4203. doi:https://doi.org/10.1016/j.biomaterials.2014.01.054
Montano, E., Vivo, M., Guarino, A. M., di Martino, O., Di Luccia, B., Calabrò, V., . . . Pollice, A. (2019). Colloidal Silver Induces Cytoskeleton Reorganization and E-Cadherin Recruitment at Cell-Cell Contacts in HaCaT Cells. Pharmaceuticals (Basel, Switzerland), 12(2). Retrieved from doi:10.3390/ph12020072
Morones-Ramirez, R. J., Winkler, J. A., Spina, C. A., & Collins, J. J. (2013). Silver enhances antibiotic activity against gram-negative bacteria. Science Translational Medicine, 5(190), 1-11. doi:DOI: 10.1126/scitranslmed.3006276
Rogers, J. V., Parkinson, C. V., Choi, Y. W., Speshock, J. L., & Hussain, S. M. (2008). A Preliminary Assessment of Silver Nanoparticle Inhibition of Monkeypox Virus Plaque Formation. Nanoscale Research Letters, 3(4), 129-133. doi:10.1007/s11671-008-9128-2
Sim, W., Barnard, R. T., Blaskovich, M. A. T., & Ziora, Z. M. (2018). Antimicrobial Silver in Medicinal and Consumer Applications: A Patent Review of the Past Decade (2007⁻2017). Antibiotics (Basel, Switzerland), 7(4), 93. doi:10.3390/antibiotics7040093