Growth Kinetics and Mechanistic Action of Reactive Oxygen Species Released by Silver Nanoparticles fromAspergillus nigeronEscherichia coli

Abstract

Silver Nanoparticles (AgNPs), the real silver bullet, are known to have good antibacterial properties against pathogenic microorganisms. In the present study AgNPs were prepared from extracellular filtrate of Aspergillus niger. Characterization of AgNPs by UV-Vis spectrum reveals specific surface plasmon resonance at peak 416 nm; TEM photographs revealed the size of the AgNPs to be 20–55 nm. Average diameter of the produced AgNPs was found to be 73 nm with a zeta potential that was −24 mV using Malvern Zetasizer. SEM micrographs showed AgNPs to be spherical with smooth morphology. EDS revealed the presence of pure metallic AgNPs along with carbon and oxygen signatures. Of the different concentrations (0, 2.5, 5, 10, and 15 μg/mL) used 10 μg/mL were sufficient to inhibit 107 CFU/mL of E. coli. ROS production was measured using DCFH-DA method and the the free radical generation effect of AgNPs on bacterial growth inhibition was investigated by ESR spectroscopy. This paper not only deals with the damage inflicted on microorganisms by AgNPs but also induces cell death through the production of ROS released by AgNPs and also growth kinetics of E. coli supplemented with AgNPs produced by A. niger.

Optimization and integration of nanosilver on polycaprolactone nanofibrous mesh for bacterial inhibition and wound healing in vitro and in vivo

“…48,49 Moreover, the interaction between NS and thiol groups of protein may induce the release of reactive oxygen species (ROS), which then inhibits the respiratory enzymes and consequently leads to cell death. 50,51 In addition, the silver ions (Ag + ) released from the NS are able to bind to the negative charge of bacterial cell wall and render bacteria more permeable. 52 Then, silver ions and NS enter the bacterial cell body and damage the sulfhydryl group in protein, which severely interfere with the DNA replication, causing cell death in the end.…”

Assessment of PVA/silver nanocomposite hydrogel patch as antimicrobial dressing scaffold: Synthesis, characterization and biological evaluation

“…AgNPs (MIC value) treated and untreated bacterial cultures (CFU~10 8 cell/mL) were incubated at 37°C, 120 rpm for 6 h. The sample was centrifuged at 300 × g at 4°C for 30 min, and the supernatant was treated with 100 μM DCFDA for 1 h [38,39,67,68]. The ROS generation in the sample was identified at 485/20 nm of fluorescence excitation wavelength, and 528/20 nm of emission wavelength using Fluorescence Multi-Detection Reader (BioTek, USA.…”

Multidimensional effects of biologically synthesized silver nanoparticles in Helicobacter pylori, Helicobacter felis, and human lung (L132) and lung carcinoma A549 cells

“…Induction of ROS synthesis leads to the formation of highly reactive radicals that destroy the cells. The possible mechanisms of H. pylori and H. felis cell death are due to membrane damage by AgNPs which relates to metal depletion, that is, the formation of pits in the outer membrane and change in membrane permeability by the progressive release of lipopolysaccharide (LPS) molecules and membrane proteins [90]. Previous studies proposed that the sites of interaction for AgNPs and membrane cells might be due to sulfur-containing proteins present in the bacterial membrane proteins [91][92][93][94][95].…”