Here, we present a review of the antibacterial effects of silver nanomaterials, including proposed antibacterial mechanisms and possible toxicity to higher organisms. For purpose of this review, silver nanomaterials include silver nanoparticles, stabilized silver salts, silver–dendrimer, polymer and metal oxide composites, and silver-impregnated zeolite and activated carbon materials. While there is some evidence that silver nanoparticles can directly damage bacteria cell membranes, silver nanomaterials appear to exert bacteriocidal activity predominantly through release of silver ions followed (individually or in combination) by increased membrane permeability, loss of the proton motive force, inducing de-energization of the cells and efflux of phosphate, leakage of cellular content, and disruption DNA replication. Eukaryotic cells could be similarly impacted by most of these mechanisms and, indeed, a small but growing body of literature supports this concern. Most antimicrobial studies are performed in simple aquatic media or cell culture media without proper characterization of silver nanomaterial stability (aggregation, dissolution, and re-precipitation). Silver nanoparticle stability is governed by particle size, shape, and capping agents as well as solution pH, ionic strength, specific ions and ligands, and organic macromolecules—all of which influence silver nanoparticle stability and bioavailability. Although none of the studies reviewed definitively proved any immediate impacts to human health or the environment by a silver nanomaterial containing product, the entirety of the science reviewed suggests some caution and further research are warranted given the already widespread and rapidly growing use of silver nanomaterials.

https://link.springer.com/content/pdf/10.1007%2Fs11051-010-9900-y.pdf

A review of the antibacterial effects of silver nanomaterials and potential implications for human health and the environment

Recent advances in nanoscience and nanotechnology radically changed the way we diagnose, treat, and prevent various diseases in all aspects of human life. Silver nanoparticles (AgNPs) are one of the most vital and fascinating nanomaterials among several metallic nanoparticles that are involved in biomedical applications. AgNPs play an important role in nanoscience and nanotechnology, particularly in nanomedicine. Although several noble metals have been used for various purposes, AgNPs have been focused on potential applications in cancer diagnosis and therapy. In this review, we discuss the synthesis of AgNPs using physical, chemical, and biological methods. We also discuss the properties of AgNPs and methods for their characterization. More importantly, we extensively discuss the multifunctional bio-applications of AgNPs; for example, as antibacterial, antifungal, antiviral, anti-inflammatory, anti-angiogenic, and anti-cancer agents, and the mechanism of the anti-cancer activity of AgNPs. In addition, we discuss therapeutic approaches and challenges for cancer therapy using AgNPs. Finally, we conclude by discussing the future perspective of AgNPs.

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Silver Nanoparticles: Synthesis, Characterization, Properties, Applications, and Therapeutic Approaches

Surface modification of inorganic nanoparticles for development of organic–inorganic nanocomposites—A review

In this article, several applications of nanomaterials in food packaging and food safety are reviewed, including: polymer/clay nanocomposites as high barrier packaging materials, silver nanoparticles as potent antimicrobial agents, and nanosensors and nanomaterial-based assays for the detection of food-relevant analytes (gasses, small organic molecules and food-borne pathogens). In addition to covering the technical aspects of these topics, the current commercial status and understanding of health implications of these technologies are also discussed. These applications were chosen because they do not involve direct addition of nanoparticles to consumed foods, and thus are more likely to be marketed to the public in the short term.

Applications of nanotechnology in food packaging and food safety: Barrier materials, antimicrobials and sensors

The antibacterial activity and acting mechanism of silver nanoparticles (SNPs) on Escherichia coli ATCC 8739 were investigated in this study by analyzing the growth, permeability, and morphology of the bacterial cells following treatment with SNPs. The experimental results indicated 10 microg/ml SNPs could completely inhibit the growth of 10(7) cfu/ml E. coli cells in liquid Mueller-Hinton medium. Meanwhile, SNPs resulted in the leakage of reducing sugars and proteins and induced the respiratory chain dehydrogenases into inactive state, suggesting that SNPs were able to destroy the permeability of the bacterial membranes. When the cells of E. coli were exposed to 50 microg/ml SNPs, many pits and gaps were observed in bacterial cells by transmission electron microscopy and scanning electron microscopy, and the cell membrane was fragmentary, indicating the bacterial cells were damaged severely. After being exposed to 10 microg/ml SNPs, the membrane vesicles were dissolved and dispersed, and their membrane components became disorganized and scattered from their original ordered and close arrangement based on TEM observation. In conclusion, the combined results suggested that SNPs may damage the structure of bacterial cell membrane and depress the activity of some membranous enzymes, which cause E. coli bacteria to die eventually.

Antibacterial activity and mechanism of silver nanoparticles on Escherichia coli.

In this study, the antifungal effects of silver nano-particles (nano-Ag) and their mode of action were investigated. Nano-Ag showed antifungal effects on fungi tested with low hemolytic effects against human erythrocytes. To elucidate the antifungal mode of action of nano-Ag, flow cytometry analysis, a glucose-release test, transmission electron microscopy (TEM) and the change in membrane dynamics using 1,6-diphenyl-1,3,5-hexatriene (DPH), as a plasma membrane probe, were performed with Candida albicans. 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 activity and mode of action of silver nano-particles on Candida albicans

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 (IC80, 1-7 microg/ml). The activity of nano-Ag was comparable to that of amphotericin B, but superior to that of fluconazole (amphotericin B IC80, 1-5 microg/ml; fluconazole IC80, 10- 30 microg/ml). 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.

Antifungal effect of silver nanoparticles on dermatophytes.

In recent years, a rapid increase in microbes that are resistant to conventional antibiotics has been observed (Goffeau, 2008). Especially, the frequency of infections provoked by opportunistic fungal strains has increased dramatically. Even though the majority of invasive fungal infections are still due to the Aspergillus or Candida species, the spectrum of fungal pathogens has changed and diversified (Denning, 1991; Ellis et al., 2000; Odds et al., 2003). Azoles that inhibit sterol formation and polyenes that bind to mature membrane sterols have been the mainstays regarding antifungal therapy for several decades (Kullberg & de Pauw, 1999; Sheehan et al., 1999). However, not only the emergence of fluconazole resistance among different pathogenic strains but also the high toxicity of amphotericin B (Alexander & Perfect, 1997; Mukherjee et al., 2003) has prompted research on new antifungal agents (Kontoyiannis et al., 2003). Bio-nanotechnology has emerged as an integration between biotechnology and nanotechnology for developing biosynthesis and environmental-friendly technology for synthesis of nanomaterials. We specifically regarded nanoparticles as clusters of atoms in the size of 1-100 nm. ‘Nano’ is a Greek word synonymous to dwarf meaning extremely small. The use of nanoparticles is gaining impetus in the present century as they posses defined chemical, optical and mechanical properties. Among them, the metallic nanoparticles are most promising as they contain remarkable antibacterial properties due to their large surface area to volume ratio, which is of interest to researchers due to the growing microbial resistance against metal ions, antibiotics, and the development of resistant strains (Rai et al., 2009; Gong et al., 2007). Different types of nanomaterials like copper, zinc, titanium (Schabes-Retchkiman et al., 2006), magnesium, gold (Gu et al., 2003), alginate (Ahmad et al., 2005) and silver have been developed but silver nanoparticles (Nano-Ag) have proved to be most effective as they exhibit potent antimicrobial efficacy against bacteria, viruses and eukaryotic micro-organisms. However, Nano-Ag used as a disinfectant drug also has some risks as the exposure to silver can cause argyrosis or argyria; it can be toxic to mammalian cells (Gong et al., 2007). 15

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The Silver Nanoparticle (Nano-Ag): a New Model for Antifungal Agents

The metastasis of hematogenous cancer cells is associated with abnormal glycosylation such as sialyl lewis antigens. Although the hepatitis B virus X protein (HBx) plays important role in liver disease, the precise function of HBx on aberrant glycosylation for metastasis remains unclear. The human hepatocellular carcinoma tissues, HBx transgenic mice and HBx-transfected cells were used to check the correlation of expressions between HBx and Sialyl lewis antigen for cancer metastasis. To investigate whether expression levels of glycosyltransferases induced in HBx-transfected cells are specifically associated with sialyl lewis A (SLA) synthesis, which enhances metastasis by interaction of liver cancer cells with endothelial cells, ShRNA and siRNAs targeting specific glycosyltransferases were used. HBx expression in liver cancer region of HCC is associated with the specific synthesis of SLA. Furthermore, the SLA was specifically induced both in liver tissues from HBx-transgenic mice and in in vitro HBx-transfected cells. HBx increased transcription levels and activities of α2-3 sialyltransferases (ST3Gal III), α1-3/4 fucosyltransferases III and VII (FUT III and VII) genes, which were specific for SLA synthesis, allowing dramatic cell-cell adhesion for metastatic potential. Interestingly, HBx specifically induced expression of N-acetylglucosamine-β1-3 galactosyltransferase V (β1-3GalT 5) gene associated with the initial synthesis of sialyl lewis A, but not β1-4GalT I. The β1-3GalT 5 shRNA suppressed SLA expression by HBx, blocking the adhesion of HBx-transfected cells to the endothelial cells. Moreover, β1-3GalT 5 silencing suppressed lung metastasis of HBx-transfected cells in in vivo lung metastasis system. HBx targets the specific glycosyltransferases for the SLA synthesis and this process regulates hematogenous cancer cell adhesion to endothelial cells for cancer metastasis.

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Hepatitis B virus X protein specially regulates the sialyl lewis a synthesis among glycosylation events for metastasis

http://koreascience.or.kr:80/article/JAKO201717447647929.pdf

Jong Guk Kim

Papers

Antifungal activity and mode of action of silver nano-particles on Candida albicans

Antifungal effect of silver nanoparticles on dermatophytes.

The Silver Nanoparticle (Nano-Ag): a New Model for Antifungal Agents

Hepatitis B virus X protein specially regulates the sialyl lewis a synthesis among glycosylation events for metastasis

Photoprotective Effect of Grape Pruning Stem Extracts on the UVB Induced HR-1 Mice Skin