Green Synthesis of Silver Nanoparticles Using Azadirachta indica Leaf Extract: Characterization, Antibacterial, and Antioxidant Properties

Abstract

In this work, we present a sustainable, green synthesis of silver nanoparticles (AgNPs) using an aqueous extract of Azadirachta indica (neem) leaves, leveraging the rich phytochemical content of flavonoids and terpenoids as both reducing and stabilizing agents under mild conditions with no hazardous chemicals Characterization by ultraviolet–visible spectroscopy revealed a sharp surface plasmon resonance peak at approximately 429 nm, confirming nanoparticle formation, while transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses indicated predominantly spherical particles with an average diameter of 18 ± 2.5 nm and a face-centered cubic crystalline structure, respectively. Antibacterial assays against Enterococcus faecalis demonstrated an inhibition zone of 16 ± 0.6 mm at 50 µg/mL, and against Staphylococcus aureus an inhibition zone of 20 ± 0.5 mm at 75 µg/mL, outperforming many chemically synthesized AgNP analogues due to enhanced surface reactivity and improved ion-release profiles The biosynthesized AgNPs also exhibited strong antioxidant activity, achieving 62 % DPPH radical scavenging efficiency comparable to ascorbic acid standards highlighting their dual therapeutic potential in combating oxidative stress–related disorders. Our findings support the application of neem-mediated AgNPs as eco-friendly antimicrobial and antioxidant agents for biomedical and environmental uses.