Biosynthesized silver nanoparticles: are they effective antimicrobials?

Abstract

BACKGROUND Silver nanoparticles (AgNPs) are increasingly being used in medical applications. Therefore, cost effective and green methods for generating AgNPs are required.OBJECTIVES This study aimed towards the biosynthesis, characterisation, and determination of antimicrobial activity of AgNPs produced using Pseudomonas aeruginosa ATCC 27853.METHODS Culture conditions (AgNO3 concentration, pH, and incubation temperature and time) were optimized to achieve maximum AgNP production. The characterisation of AgNPs and their stability were evaluated by UV-visible spectrophotometry and scanning electron microscopy.FINDINGS The characteristic UV-visible absorbance peak was observed in the 420–430 nm range. Most of the particles were spherical in shape within a size range of 33–300 nm. The biosynthesized AgNPs exhibited higher stability than that exhibited by chemically synthesized AgNPs in the presence of electrolytes. The biosynthesized AgNPs exhibited antimicrobial activity against Escherichia coli, P. aeruginosa, Salmonella typhimurium, Staphylococcus aureus, methicillin-resistant S. aureus, Acinetobacter baumannii, and Candida albicans.MAIN CONCLUSION As compared to the tested Gram-negative bacteria, Gram-positive bacteria required higher contact time to achieve 100% reduction of colony forming units when treated with biosynthesized AgNPs produced using P. aeruginosa.

Antimicrobial Nanoparticles: applications and mechanisms of action

“…Bacteria, fungi and plants have recently gained much attention due to their ability to biosynthesize metal NPs by an environmentally friendly process. For example, silver nanoparticles have been successfully made from Staphylococcus aureus, Pseudomonas aeruginosa, 7 Escherichia coli, Acinetobacter species, 8 Lactobacillus species, 9 Klebsiella pneumoniae 10 and Enterobacter cloacae 11 . An advantage of biological synthesis methods is the higher stability of the AgNPs compared to chemically synthesized NPs.…”

“…Both chemically synthesized and biosynthesized silver nanoparticles have been shown to inhibit Gram negative and Gram positive bacteria as well as yeasts. 7 Stronger antimicrobial activity was shown against Gram negative bacteria which can be attributed to the thicker cell wall composition of Gram positive bacteria. A number of mechanisms have been attributed to the bactericidal activity of silver NPs.…”

Silver nanoparticles induce Egr‐1‐dependent psoriasin expression via the ERK and p38 pathways

“…Salomoni et al . and Peiris et al . reported that Ag‐NPs showed antibacterial effect against Pseudomonas aeruginosa , Escherichia coli , Salmonella typhimurium , Staphylococcus aureus , Acinetobacter baumannii and Candida albicans .…”

“…Peiris et al 15 reported that Ag-NPs showed antibacterial effect against Pseudomonas aeruginosa, Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Acinetobacter baumannii and Candida albicans. There have been a few suggestions regarding the mechanism of the antimicrobial activity of Ag-NPs.…”

The state of nanomedicine in Sri Lanka: challenges and opportunities

“…However, there is a great potential with the limited number of scientists who are actively associated with research in nano-drug carriers, antibacterial agents, and bone prostheses. These include development of bone prostheses (Rajapakse et al, 2016), drug encapsulation, for example, Vitamin C (Samantha Dissanayake et al, 2015), targeted cancer treatment (Katuwavila et al, 2016a;Weerasuriya et al, 2017;Nwokwu et al, 2017;Manatunga et al, 2017;Manatunga et al, 2018a), and developing antimicrobial agents (Peiris et al, 2017;Rathnayake et al, 2018). Rajapakse et al have actively engaged in nano hydroxyapatite-based biomaterials ( Fig.…”