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Description
This study deals with the green synthesis of AgNPs in an aqueous solution using leaf extract of Allium ampeloprasum to reduce silver ions and stabilize the formed nanoparticles while also determining the antioxidant activity of the nanoparticles by DPPH radical scavenging assay. The fresh leek leaves were extracted by boiling 25 g of leaves in 100 mL deionized water for 45 min at 80 °C. For the synthesis of AgNPs, 5 mL of the prepared plant extract was mixed with 45 mL of 0.1 M silver nitrate solution. The initial pH of the reaction mixture was 5.5 and it was adjusted to 12.0 using sodium hydroxide. The whole reaction mixture was then allowed to proceed at room temperature for 45 min.
The formation of AgNPs was first observed when the color changed to honey-brown/dark brown, which is due to the reduction of Ag⁺ ions. The nanoparticles were further characterized by UV–visible spectroscopy, FTIR, SEM, XRD, AFM, and DPPH assay. FTIR spectra confirmed the presence of phenolic hydroxyl, carboxyl, and protein-related amide groups in the process of reduction, capping, and stabilization. The SEM images displayed mainly spherical but aggregated nanoparticles; the crystalline nature of AgNPs was confirmed by XRD, which estimated an average size of about 45 nm. AFM images further supported the phytochemical coverage on the nanoparticle surface. The biosynthesized AgNPs showed moderate DPPH radical scavenging activity compared to ascorbic acid, which proves to be a good antioxidant. In general, the leaf extract of A. ampeloprasum is a good green synthesizer for stable AgNPs with antioxidant activity.
