Characterization, antioxidant, antibacterial, and antibiofilm properties of biosynthesized Ag/AgCl nanoparticles using Origanum ehrenbergii Boiss

Abstract

In the current study, silver/silver chloride nanoparticles (Ag/AgCl-NPs) were synthesized using the leaf extract of the endemic Lebanese plant, Origanum ehrenbergii Boiss, as the reducing medium. The structure, morphology, and physiochemical characteristics of the synthesized AgNPs were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet–visible (UV) absorption spectroscopy, and Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL). The antioxidant activity of the AgNPs was assessed according to the 2, 2-diphenyl−1-picrylhydrazyl (DPPH) assay. The antibacterial effect of the AgNPs was investigated using the broth microdilution method, agar well diffusion, Time-kill test, and biofilm inhibition and eradication assays. This is the first report dealing with the characterization, antioxidant, and antibacterial properties of biosynthesized Ag/AgCl-NPs using the plant Origanum ehrenbergii Boiss. The findings demonstrated the synthesis of face-centered cubic (fcc) Ag/AgCl-NPs with a mean particle size of 15 nm that displayed remarkable antioxidant capacity and inhibitory activities against eight bacteria; 3 g-positive (Enterococcus faecium, Staphylococcus aureus, and Staphylococcus haemolyticus) and 5 g-negative bacteria (Pseudomonas aeruginosa, Citrobacter braakii, Escherichia coli, Stenotrophomonas maltophilia, and Klebsiella pneumoniae). The synthesized AgNPs inhibited the growth of bacteria after 3 h. Ag/AgCl-NPs exhibited inhibitory effects on the bacterial biofilms’ formation as well as on pre-formed biofilms. These results highlight the potential to use these biosynthesized Ag/AgCl-NPs as antibacterial, antibiofilm, and antioxidant agents.