Phytosynthesis, Characterization and Antimicrobial Studies of Silver Nanoparticles Using Aqueous Extracts of Olax Subscorpioidea

In this study, aqueous extracts of the leaf and root of Olax subscorpioidea were used as solvent, reducing and stabilizing agents in synthesizing silver nanoparticles (AgNPs). The change in color from colorless to dark brown indicated the AgNPs formation. The UV-Vis spectra showed active absorption at 460 nm for the root extract mediated AgNPs attributed to the surface plasmon resonance of the AgNPs. This absorbance is quite intense compared to that of the leaf, which is slightly shifted to a higher wavelength of 465 nm. The FTIR spectra showed absorption bands attributed to O-H and N-H stretching vibrations of the phenolic/amide groups. In addition, the bands due to symmetric stretching vibrations of C-H and carbonyl (C=O) groups are also observed. The bioactive molecules present in the plant extracts do stabilized not only the metal nanoparticles but also play the role of modifying the surface of the particles owing to their different functionalities. The textural properties studied using Brunauer-Emmett-Teller (BET) method gave a specific surface area of 22.84 and 39.8 m2/g, respectively for root and leaf mediated AgNPs. Scanning electron microscopy (SEM) revealed monodisperse microspheres AgNPs, while the transmission electron microscopy (TEM) showed particles in the nanosize regime. The results of the antimicrobial activities showed the Olax subscorpioidea mediated-AgNPs to be effective in inhibiting the growth of bacterial strains more than the antibiotic drugs under investigation.