Comparative green synthesis and physicochemical characterization of silver nanoparticles using Thymus vulgaris extracts from Syrian and Yemeni sources

Environmentally benign synthesis of silver nanoparticles (AgNPs) using plant-derived materials has emerged as an attractive strategy for producing functional nanomaterials while avoiding hazardous chemical procedures. In the present study, aqueous extracts of Thymus vulgaris obtained from Syrian and Yemeni commercial sources were employed for the green synthesis of AgNPs, followed by a comparative physicochemical characterization. To our knowledge, this is among the few studies comparing the physicochemical characteristics of AgNPs synthesized using T. vulgaris extracts obtained from two different commercial sources. UV-Vis spectroscopy revealed distinct absorption bands at 319.1 nm and 282.9 nm for the Syrian- and Yemeni-derived preparations, respectively. Dynamic light scattering analysis showed hydrodynamic diameters of 84.18 nm and 125.2 nm, whereas zeta potential measurements yielded values of −26.9 mV and −30.1 mV, indicating negatively charged nanoparticle surfaces. Quantitative TEM analysis based on measurements of 50 nanoparticles per sample revealed average particle diameters of 13.38 ± 5.26 nm and 12.34 ± 5.31 nm for Syrian- and Yemeni-derived AgNPs, respectively. SEM and TEM analyses demonstrated predominantly spherical nanoparticles with varying degrees of aggregation. EDS analysis confirmed silver as the major elemental constituent, while XRD analysis verified the crystalline metallic nature of the nanoparticles with a face-centered cubic structure and estimated crystallite sizes of 11.3 nm and 8.3 nm, respectively. Overall, the findings demonstrate that Thymus vulgaris extracts can serve as effective reducing and stabilizing agents for the green synthesis of crystalline silver nanoparticles. Although minor physicochemical differences were observed between the two nanoparticle preparations, further studies incorporating detailed phytochemical characterization are required to clarify the factors underlying these variations.