Artemisia afra (Ariti) Leaf Extract–Mediated Ag/SiO ₂ Nanocomposites for Antibacterial Activity

Nanotechnology is the science and engineering that is responsible for antibacterial activity. In this study, we used the green method to synthesize Ag/SiO 2 nanocomposites (NCs) for antibacterial activity. In the synthesis method, Artemisia afra is employed as stabilizing, capping, and reducing agents. The synthesized materials were characterized using UV‐visible spectroscopy; x‐ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) instruments. UV‐visible spectroscopy was used to estimate optical properties of the fabricated materials and showed the formation of Ag/SiO 2 NCs at an absorption band of 390 nm and 411 nm. From the XRD spectra, the average crystallite size of silver nanoparticles (AgNPs) and Ag/SiO 2 NCs were 16.68 nm and 8.99 nm, respectively. The functional group of AgNPs and Ag/SiO 2 NCs were confirmed by the FTIR spectroscopic technique. The materials exhibited 3369 cm −1 from stretching vibration of ‐OH functional groups and 539 cm −1 from interaction of Ag with protein molecules in the extract. The SEM image was confirmed the surface morphological structure of the synthesized materials. The results showed that the AgNPs were spherical in shape with a little aggregation and the NCs were spherical in shape. The antibacterial activity tests were conducted by using disc diffusion methods and showed better activity (21.0 ± 0.25 for S. pyogenes , 20.0 ± 0.12 for S. aureus , 18 ± 0.1 for E. coli , and 17 ± 0.1 for P. aeruginosa ) on composites than Ag NCs. This might be due to SiO 2 increasing the stability and preventing the aggregation of AgNPs.