title: Antibacterial effect of silver nanoparticles on Staphylococcus aureus.
abstract: Antibacterial activity of silver nanoparticles (AgNPs) was investigated using Staphylococcus aureus PTCC1431 as a model of Gram-positive bacteria. The mechanism of antibacterial activity of AgNPs was then studied by analyzing the growth, morphology, and molecular variations in the cell wall. Experimental data showed that AgNPs at a concentration of 4 μg/ml completely inhibited bacterial growth. Transmission electron microscopy results confirmed cell wall damage produced by AgNPs as well as accumulation of AgNPs in the bacterial membrane. Meanwhile, the AgNP-treated bacteria were monitored by circular dichroism to reveal peptidoglycan variations. Some degree of variation in the α-helix position of the peptide chain was observed. Moreover, increasing the AgNP concentration to 8 μg/ml resulted in release of muramic acid (MA) into the medium, which could be attributed to cell wall distraction. A gas chromatography-tandem mass spectrometry analysis and release of MA, as a bacterial indicator, showed that glycan strands may also be decomposed as a result of AgNP treatment.
authors.affiliation: Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, G.C. Evin, P.O. Box: 19835-389, Tehran, Iran. f_mirzajnai@scientist.com
authors.forename: Fateme
authors.initials: F
authors.lastname: Mirzajani
authors.forename: Alireza
authors.initials: A
authors.lastname: Ghassempour
authors.forename: Atousa
authors.initials: A
authors.lastname: Aliahmadi
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Esmaeili
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008826:Microbial Sensitivity Tests; D012834:Silver / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D012834:Silver