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|a In the present study, gold (AuNPs) and gold-silver bimetallic nanoparticles (Au-Ag BMNPs) were fabricated by using aqueous leaf extract of Triticum aestivum L. - a crop plant, and their bactericidal potency was checked against selected pathogenic bacterial strains. The phytofabricated AuNPs and BMNPs were analyzed for their physical attributes using UV-Visible and Fourier transformed infrared spectroscopy (FTIR), Dynamic light scattering (DLS), High-resolution transmission electron microscopy (HRTEM), and En-ergy-dispersive X-ray spectroscopy (EDX). Bactericidal efficiency of synthe-sized NPs was evaluated using agar-well diffusion and XTT (2,3-Bis-(2- Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide)-colorime tric assays against Klebsiella pneumoniae, Salmonella typhimurium, Entero-bacter aerogenes, Escherichia coli, Micrococcus luteus, Staphylococcus aure-us, Streptococcus mutans and Staphylococcus epidermidis. HRTEM analysis revealed that both kinds of nanoparticles (NPs) were highly crystalline in nature and of spherical to oval-shaped. AuNPs size was found in the range of 5-40 nm, whereas BMNPs showed their size in the range of 5-30 nm. HRTEM results were corroborated by DLS results which revealed the aver-age hydrodynamic diameter of AuNPs and BMNPs in the range of 29.08 and 26.56 nm respectively. UV-visible spectroscopy showed high-intensity single spectral peaks at 540 and 480 nm for AuNPs and BMNPs respectively. FTIR analysis demonstrated that protein, flavanones, hydroxyl, carboxylate groups and reducing sugars were responsible for reducing and capping of both NPs. K. pneumonia and S. typhimurium were found to be the most sen-sitive bacteria towards BMNPs-mediated (MIC: 400 μg/ml) and AuNPs-mediated toxicity (MIC: 800 μg/ml). It was observed that BMNPs generally possessed more powerful bactericidal effect against all bacterial strains in comparison to AuNPs. Minimum inhibitory concentration (MIC) and Mini-mum bactericidal concentration (MBC) values were observed in the concen-tration range of 400 μg/ml-1.5 mg /ml for different bacterial strains. Further-more, it was demonstrated that phytosynthesized AuNPs have their own bactericidal effect, but at higher concentrations (>100 μg/ml) and bacteri-cidal effect of BMNPs was due to the synergistic effect of both Ag and Au ions, which was also observed to be dose-dependent. © 2022 Horizon e-Publishing Group. All rights reserved.
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