Antimicrobial and antibiofilm activity of green synthesized silver nanoparticles by using aqueous leaf extract of Thymus serpyllum

Abstract

Recently, metal nanoparticles have attracted the attention of researchers due to their unique properties when compared with bulk materials and have become used in many fields of application. In this study, green synthesis of Ag nanoparticles (AgNPs) was investigated by using aqueous extract of Thymus serpyllum leaves. In addition, antimicrobial and antibiofilm activities of the synthesized AgNPs were evaluated in this study. Further, UV-vis spectrophotometer, FTIR, DLS, SEM with EDX and TEM were used for characterization of the green synthesized AgNPs. The UV-vis spectrum of the synthesized AgNPs had a maximum peak at 467 nm. Also, TEM analysis indicated spherical particles with an average size of 25.2 nm. The synthesized AgNPs have higher stability (zeta potential: -29.5 mV). The antimicrobial activity of the green synthesized AgNPs was investigated on both Gram-positive and Gram-negative bacteria, such as Bacillus cereus, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium using agar well diffusion assay. According to the results of the study, Gram-positive bacteria showed larger inhibition zones compared to Gram-negative bacteria. Finally, the AgNPs were explored for the inhibition of S. aureus biofilms. AgNPs at 100 μg/mL concentration showed a high inhibition value of about 73% for S. aureus biofilm formation. So, it is concluded that the synthesized AgNPs might be potentially used in many applications due to their antimicrobial and antibiofilm properties.