Introduction: There has been growing interest in using environmentally friendly methods of synthesizing nanoparticles without using substances risky to the environment and human health. The aims of this study were biosynthesis of silver nanoparticles using different tree gum extracts and evaluation of the toxicity of nanoparticles and their salts against two bacteria: Escherichia coli and Staphylococcus aureus.
 
Materials & Methods: In this study, silver nanoparticles (SNPs) synthesized from manna of Quercus, Cerasus avium, and Prunus armeniaca gum extracts were investigated for their antibacterial activity. Silver nanoparticles were prepared from the reduction of silver nitrate. Copper nanoparticles (CuNPs) were formed by reduction of CuCl₂ with L-ascorbic acid. Prepared nanoparticles were characterized by ultraviolet-visible spectroscopy and TEM techniques. Antibacterial activities of the nanoparticles were tested against Staphylococcus aureus and Escherichia coli.
Findings: In the present study, biosynthesis and characterization of SNPs using Cerasus avium and Prunus armeniaca gum extracts is reported for the first time. The spectrum of the reaction mixture showed a strong absorption peak at 420 nm. TEM image showed that Ag-NPs (SNPs) formed were well dispersed with a spherical structure and 10 to 30 nm particle size range. Bacteria (E. coli and S. aureus) showed clear hypersensitivity to silver and copper nanoparticles, and the effects of SNPs were more notable than those of CuNPs. Data analysis showed that CuCl₂ and AgNO₃ nanoparticles had a lower inhibitory effect.
 
Discussion & Conclusions: Our results showed these microorganisms had sensitivity against the tested nanoparticles; however, E. coli showed higher sensitivity than S. aureus to both nanoparticles.