Amrina Suleman

Nanotechnology has received a lot of attention from the scientific community because of the greater surface-to-volume ratio of nanomaterials, which phenomenally increases their efficacy in practical applications. Among the various synthesis techniques, the biogenic or green synthesis of nanomaterials shows advantages over other techniques such as physical, chemical, etc. This study reports the biogenic synthesis of silver nanoparticles (AgNPs) using aqueous bark extract of Aesculus indica. The as-synthesized NPs were characterized by UV–visible, FT-IR, XRD, and SEM, and then tested for their antioxidant and antimicrobial potency. We have identified phenols, flavonoids, tannins, saponins, and carbohydrates in the bark extract of A. indica. The extract-loaded-AgNPs showed the highest inhibition for Staphylococcus aureus (28.0 mm), Pseudomonas aeruginosa (17.66 mm), Escherichia coli (14.33 mm), Acetobacter serratia (14.00 mm), and Klebsiella pneumoniae (12.33 mm). The methanolic bark extract inhibited S. aureus (24.33 mm), P. aeruginosa (10.66 mm), E. coli (11.33 mm), A. serratia (9.66 mm), and K. pneumoniae (11.66 mm). Aqueous bark extract inhibited S. aureus (22.33 mm), P. aeruginosa (8.33 mm), E. coli (9.33 mm), A. serratiaa (8.33 mm), and K. pneumoniae (9.66 mm). Its aqueous extract showed the highest antioxidant potency; IC₅₀ (0.175 µg/mL) followed by the methanolic extract; IC₅₀ (0.210 µg/mL) and extract-loaded nanoparticles; IC₅₀ (0.901 µg/mL). Our findings provide meaningful interest for antioxidant, anti-microbial applications of, and AgNPs synthesis by, aqueous bark extract of A. indica.

Herein, we report the green synthesis of silver nanoparticles using the aqueous extract of root of Angilica glauca Edgew. UV-vis and FT-IR spectroscopies, X-ray diffraction analysis and scanning electron microscopy technique were employed to structurally and morphologically characterize the green synthesized silver nanoparticles. The nanoparticles were found to be spherical in shape with an average size of ∼21 nm. The extract was found to be rich in phenolic and flavonoid contents. Both the extract and the extract-loaded silver nanoparticles inhibited the growth of both Pseudomonas aeruginosa (inhibition zone 13.0 ± 1.6 and 4.0 ± 0.9 mm, respectively) and Escherichia coli (inhibition zone 12.0 ± 1.1 and 3.0 ± 0.6 mm, respectively) at 9.0 µg/mL. The antioxidant potential of the extract (IC₅₀ = 30.79 ± 3.2 µg/mL) was determined via DPPH radical scavenging assay. These nanoparticles are concluded to possess antibacterial potentials.