Antimicrobial activity of fluorescent Ag nanoparticles

Abstract

Significance and Impact of the Study: This study aims to demonstrate the size and shape-dependent antimicrobial activity of Ag nanoparticles. It is shown for the first time that the fluorescent Ag nanoparticles of 1Á5 nm have superior antimicrobial activity with respect to the larger particles. The shape and size of the particles actually control their activity. The smaller particles can easily penetrate the cell wall and have pronounced activity. These findings may be useful in the development of potential antimicrobial agents. AbstractThe antimicrobial activity of fluorescent Ag nanoparticles of 1Á5 nm (nAg-Fs) is demonstrated and compared with the other Ag nanoparticles of different shapes and size. The antimicrobial activity was evaluated using Gram-positive (Staphylococcus epidermidis NCIM2493 and Bacillus megaterium) and Gramnegative bacteria (Pseudomonas aeruginosa ATCC27853 and Escherichia coli) and fungal strains (Candida albicans and Aspergillus niger). Insights into the possible mechanism were investigated using fluorescence microscope and cytoplasmic materials release assay. The fluorescence microscopic measurements show that the nAg-Fs are localized at the centre of the cell, and 50% decrease in the fluorescence intensity was observed upon 2-h incubation. Maximum cytoplasmic release was observed with spherical Ag nanoparticles of 10 nm. Although the nAg-F shows minimum cytoplasmic release, it has the highest activity. The microbial killing effect of nAg-Fs is actually originates from its intracellular activity. The antimicrobial activity of nAg-Fs is significantly higher than the other synthesized nanoparticles of different shapes and size. The activity of the nanoparticles has been rationalized by considering the shape, size and surface structure of the particles.

Silver nanoparticle-enriched diamond-like carbon implant modification as a mammalian cell compatible surface with antimicrobial properties

“…Silver susceptibility of microbes depends on species- or even strain-specific mechanisms reflecting variations in metabolizing silver or repairing silver-related cell damages. Antimicrobial properties of silver and silver nanocomposites towards many different microbes including also methicillin-resistant S. aureus (MRSA) have been well documented by others 28 29 30 31 . Interestingly, the acting molecular mechanisms of silver toxicity are complex and not limited to specific pathways offering therefore a broader antimicrobial profile and virtually no bacterial resistance in contrast to antibiotics 31 32 .…”

Application of Light Scattering Techniques to Nanoparticle Characterization and Development

“…Different authors have explored this issue, even in polymeric-coated magnetic NPs, which were consider less toxic than the uncoated, but high dosages during a larger period of time increase cytotoxic and genotoxic effects on macrophages (Jena et al, 2012 ; Mohanty et al, 2012 ). With nanoparticles activity being dependent of their physicochemical properties, namely size, shape, and surface, their toxicity toward cells is also dependent of these properties (Bera et al, 2014 ; Sun et al, 2014 ; Rajchakit and Sarojini, 2017 ). A strategy followed to deal with these problems has been the development of different types of nanoparticles, including polymeric nanoparticles, micelles, or liposomes, with the advantage of being possible to shape their properties to increase the efficacy in targeting or drug delivering (Xie et al, 2014 ; Bilal et al, 2017 ; Solairaj et al, 2017 ).…”

Recent Nanotechnology Approaches for Prevention and Treatment of Biofilm-Associated Infections on Medical Devices

“…Silver in ionic or NP form has an oligodynamic effect with broad spectrum antibacterial activity and is especially effective against microbial colonizations associated with biomedical infections. The antibacterial mechanism of silver NPs (Ag NPs) is probably due to interactions between silver ions with bacterial wall sulfhydryl groups that interfere with and disrupt bacterial cell membranes [158], enzyme activities [159], respiratory chains [160], and cell proliferation [161]. Ag NPs have also been shown to disrupt biofilm matrices by perturbing intermolecular forces.…”