Biosynthesis and characterization of silver nanoparticles using root extract of Saussurea lappa (Decne.) Clarke and their antibacterial activity

Aim: To synthesize and characterize stable silver nanoparticles (AgNPs) from the root extract of Saussurea lappa, a medicinally important plant. The AgNPs was further evaluated for their antibacterial activity. Methodology: The biosynthesised AgNPs were characterised by change in colour pattern and confirmed by UV–Visible spectroscopy, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Results: UV-Vis spectroscopy study showed characteristic surface plasmon band (SPR) of synthesized AgNPs at 418 nm. FTIR studies revealed presence of some biomolecules responsible for reduction, stabilization and capping agents towards these synthesized AgNPs. TEM analysis revealed that the size of AgNPs ranged between 7.13 – 24.0 nm and had spherical shape. XRD data showed face-centered cubic (fcc) nature of AgNPs. The synthesized AgNPs showed significant antibacterial activity against one Gram positive (Bacillus cereus) and one Gram negative (Escherichia coli) bacterial strain. Interpretation: The biologically synthesized nanoparticles from the root extract of S. lappa were stable and showed enhanced antibacterial activity against both type of bacterial strains and could be utilized for industrial and remedial purposes.