Antibacterial properties of silver nanoparticles synthesized using Pulicaria glutinosa plant extract as a green bioreductant

Mujeeb Khan,¹ Shams Tabrez Khan,² Merajuddin Khan,¹ Syed Farooq Adil,¹ Javed Musarrat,² Abdulaziz A Al-Khedhairy,² Abdulrahman Al-Warthan,¹ Mohammed Rafiq H Siddiqui,¹ Hamad Z Alkhathlan<sup>1

1</sup>Department of Chemistry, ²Zoology Department, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia

Abstract: The antibacterial properties of nanoparticles (NPs) can be significantly enhanced by increasing the wettability or solubility of NPs in aqueous medium. In this study, we investigated the effects of the stabilizing agent on the solubility of silver NPs and its subsequent effect on their antimicrobial activities. Silver NPs were prepared using an aqueous solution of Pulicaria glutinosa plant extract as bioreductant. The solution also acts as a capping ligand. During this study, the antimicrobial activities of silver NPs, as well as the plant extract alone, were tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Micrococcus luteus. Silver NPs were prepared with various concentrations of the plant extract to study its effect on antimicrobial activity. Interestingly, various concentrations of P. glutinosa extract did not show any effect on the growth of tested bacteria; however, a significant effect on the antimicrobial property of plant extract capped silver NPs (Ag-NPs-PE) was observed. For instance, the half maximal inhibitory concentration values were found to decrease (from 4% to 21%) with the increasing concentrations of plant extract used for the synthesis of Ag-NPs-PE. These results clearly indicate that the addition of P. glutinosa extracts enhances the solubility of Ag-NPs-PE and, hence, increases their toxicity against the tested microorganisms.

Keywords: antibacterial activity, silver nanoparticles, plant extract, Pulicaria glutinosa

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