Green synthesis of silver nanoparticles mediated by Pulicaria glutinosa extract

Mujeeb Khan,¹ Merajuddin Khan,¹ Syed Farooq Adil,¹ Muhammad Nawaz Tahir,² Wolfgang Tremel,² Hamad Z Alkhathlan,¹ Abdulrahman Al-Warthan,¹ Mohammed Rafiq H Siddiqui<sup>1

1</sup>Department of Chemistry, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia; ²Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-University of Mainz, Mainz, Germany

Abstract: The green synthesis of metallic nanoparticles (NPs) has attracted tremendous attention in recent years because these protocols are low cost and more environmentally friendly than standard methods of synthesis. In this article, we report a simple and eco-friendly method for the synthesis of silver NPs using an aqueous solution of Pulicaria glutinosa plant extract as a bioreductant. The as-prepared silver NPs were characterized using ultraviolet–visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. Moreover, the effects of the concentration of the reductant (plant extract) and precursor solution (silver nitrate), the temperature on the morphology, and the kinetics of reaction were investigated. The results indicate that the size of the silver NPs varied as the plant extract concentration increased. The as-synthesized silver NPs were phase pure and well crystalline with a face-centered cubic structure. Further, Fourier-transform infrared spectroscopy analysis confirmed that the plant extract not only acted as a bioreductant but also functionalized the NPs' surfaces to act as a capping ligand to stabilize them in the solvent. The developed eco-friendly method for the synthesis of NPs could prove a better substitute for the physical and chemical methods currently used to prepare metallic NPs commonly used in cosmetics, foods, and medicines.

Keywords: surface plasmon resonance, metallic nanoparticles, eco-friendly, capping ligand