Iranian Journal of Chemical Engineering (IJChE)

Abstract This study presents the premier report of gold nanoparticle (AuNP) synthesis using Teucrium polium (T. polium) plant extract, investigating the antimicrobial activity of both aqueous and methanolic T. polium extracts and the synthesized AuNPs. Additionally, the effect of different concentrations of synthesized AuNPs on the phytochemical properties of T. polium plant extract was examined. The results of Ultraviolet-visible spectroscopy (UV-Vis spectroscopy), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared (FTIR) tests on AuNPs confirmed their synthesis. SEM and TEM images showed that the AuNPs were spherical in shape with an average size of 22.89 nm. The surface plasmon resonance (SPR) peak of the UV-Vis spectroscopy corresponding to the synthesized AuNPs appeared at 420 nm. The optimal pH of the reaction solution was also equal to 5. According to the results, the methanolic extract exhibited significantly higher antibacterial and antifungal activity compared to the aqueous extract, with the maximum inhibition zone diameters observed for Escherichia coli (14±1.4 mm) and Aspergillus Niger (15±0.7 mm). Moreover, the antimicrobial activity of AuNPs showed that these nanoparticles have relatively good ability to inhibit gram-negative bacteria, with the largest inhibition zone diameters observed for Escherichia coli (18±0.7 mm) and Aspergillus niger (20±0.9 mm). The antioxidant and reducing power activity (phenolic flavonoids content) of T. polium plant extract treated with different concentrations of synthesized AuNPs increased with increasing nanoparticle concentrations up to 60 ppm (IC50=9.94 µg/mL and reducing power= 16.85 mMFe²⁺/mg sample), and decreased at higher concentrations.

Abstract In contemporary society, a plethora of human industries are fundamentally dependent on the antibacterial capabilities of various nanoparticles, rendering their absence in contemporary applications nearly unimaginable. Silver nanoparticles (AgNPs) are widely used for their potent antibacterial properties in various applications, including medical and industrial settings. Controlling microbial growth is critical to prevent health and environmental issues. In this study, AgNPs is biosynthesized using the Celtis caucasica leaf extract, optimizing synthesis parameters to achieve high purity and uniform particle size. The ideal synthesis parameters involved combining 1.5 mL of plant leaf extract with 10 mL of a 3 mM AgNO3 solution, maintaining a pH of 7, and heating the mixture at 70 °C for 45 minutes.UV-Vis, FTIR, and TEM analyses verified the synthesis of nearly spherical AgNPs with a mean size of approximately 20 nm, displaying a typical SPR absorption peak at 425 nm. FTIR data revealed key bioactive groups in the extract that enabled Ag⁺ ion reduction. The AgNPs showed robust antibacterial effects against Staphylococcus aureus (MIC 12.5 µg/mL) and Escherichia coli (MIC 25 µg/mL).