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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.

1-ethyl-3-methylimidazolium acetate (EMIMOAC) and 1-buthyl-3-methylimidazolium acetate (BMIMOAC) ionic liquids have been used as a solvent and stabilizing agent in an attempt to prepare cobalt nanoparticles via chemical reduction method. The SEM and UV-Vis techniques confirm the formation of nanoparticles. XRD reveals the nanocrystalline nature of the products with average crystallite size of 27.5 and 24.1 nm for CoEMIMOAC and CoBMIMOAC, respectively. The SEM and EDAX morphological/atomic weight ratio analyses show not much difference between the nanocrystals formed in EMIMOAC or BMIMOAC. These results indicate that the cationic part of the ionic liquid did not play significant role during nucleation and growth of the particles. The zone of inhibition of CoEMIMOAC obtained against Staphylococcus aureus and Escherichia coli are 23 and 14 mm, respectively whereas that of CoBMIMOAC against the bacterial under investigation is 15 mm. The synthesized nanocrystals have therefore demonstrated great potentials as nanodrugs in the treatment of infections caused by gram-positive microorganisms.