Green biogenic synthesis of silver nanoparticles: a thoroughly exploration of characterization and biological efficacy
Authors:   Department of Chemistry, College of Science, Princess Nourah bint a Abdulrahman University, P.O. Box 84427, Riyadh 11671, Saudi Arabia, Almasoud N. , Alomar T. S. ,   Department of Chemistry, College of Science, Princess Nourah bint a Abdulrahman University, P.O. Box 84427, Riyadh 11671, Saudi Arabia, Aldehaish H. A. ,   Department of Botany and Microbiology, King Saud University, Riyadh, b Kingdom of Saudi Arabia, Awad M. A. , Alwahibi M. S. ,   Department of Botany and Microbiology, King Saud University, Riyadh, b Kingdom of Saudi Arabia, Alsalem K. A. ,   College of Medicine, Imam Mohammad Ibn Saud Islamic University, Riyadh, d Kingdom of Saudi Arabia, Rai S. ,   National Archives, Ministry of Culture, Tourism and Civil Aviation, Government of Nepal, Kathmandu 44600, Nepal, Bhattarai A. ,   National Archives, Ministry of Culture, Tourism and Civil Aviation, Government of Nepal, Kathmandu 44600, Nepal, Almutlaq S. ,   Department of Chemistry, College of Science, Princess Nourah bint a Abdulrahman University, P.O. Box 84427, Riyadh 11671, Saudi Arabia, Alsudairi B. ,   Department of Chemistry, College of Science, Princess Nourah bint a Abdulrahman University, P.O. Box 84427, Riyadh 11671, Saudi Arabia, Alamr R. ,   Department of Chemistry, College of Science, Princess Nourah bint a Abdulrahman University, P.O. Box 84427, Riyadh 11671, Saudi Arabia, Alowais H. ,   Department of Chemistry, College of Science, Princess Nourah bint a Abdulrahman University, P.O. Box 84427, Riyadh 11671, Saudi Arabia
Published: November 2024

Conventional physical and chemical methods for synthesizing silver nanoparticles (AgNPs)
often use reducing agents, and other chemicals that are harmful to the environment because
of their toxic properties. This has prompted significant concern and the need to develop
environmentally acceptable approaches. Due to the constraints of traditional chemicalphysical methods, green synthesis methods are being developed to fill these gaps by utilizing
biological components extracted from plants. These plant-derived biomolecules are highly
specific and facilitate the creation of metal nanoparticles. AgNPs, produced through these
methods, possess a wide variety of metabolites with antibacterial effects. In light of this, the
current investigation aimed to produce AgNPs using aqueous extracts obtained from
Moringa leaves (Ml), Juniper leaves (Jl), and Juniper beans (Jb)via a green chemistry
technique. Various analytical methods, including UV-visible spectrophotometry (UV-Vis),
transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier
transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray spectroscopy (EDX)
analysis, were employed to characterize the synthesized AgNPs. After adding the plant
extracts, the color of the aqueous silver nitrate solution noticeably changed to brown.
Furthermore, a shift in absorption spectra was noted, with absorbance peaks appearing
around λmax = 449.5 nm, 478.5 nm, and 440.5 nm for Juniper leaves, Jb, and Moringa
extracts, respectively. DLS analysis revealed that the synthesized AgNPs varied in size and
polydispersity index (PDI) values, with sizes of 108 nm (PDI = 0.246), 101 nm (PDI =
0.278), and 161 nm (PDI = 0.240) form Jl, Jb, and Ml extracts, respectively. These
nanoparticles displayed no agglomeration and were stable over a long period. Transmission
electron microscope/TEM analysis confirmed the synthesis of well/dispersed AgNPs with
an average sizes of less than 22 nm, displaying different shapes likely due to the variety of
capping agents present in the bean and leaf extracts. Elemental profiles showed a peak at 3
keV for the synthesized AgNPs, indicating a high proportion of silver elements in all three
samples. The synthesized nanoparticles were also subjected to biological screening. The
investigation involved testing their antibacterial activity against various bacterial and fungal
strains. The Jlnano extract exhibited significant antifungal activity. Conversely, the aqueous
and nano-extracts of Ml showed less effectiveness against fungal growth. The plant nano
extracts, in particular, demonstrated a clearer effect against all tested fungi compared to the
plant aqueous extracts. Among the AgNPs synthesized, those from Moringa extract had the
greatest effect on Gram-positive bacteria (S. aureus), with an inhibitory zone diameter of
4.5 mm.