2.6 Synthesis of silver nanoparticl

2.6 Synthesis of silver nanoparticlesA 25 mL (50% v/v) of each extract solution was used for thereduction process and was added to 25 mL of aqueous AgNO3solution of 100 mg/L concentration. The solutions were keptat 60 °C during the reduction process and similar conditionswere maintained for each extract. The color change of thecolloidal solution was monitored by visual inspection.Digital images of the samples were also captured with a digitalstill camera (Cannon 550D) at an optical zoom of × 4.2.7 Characterizations of AgNPsThe nanoparticle formation was monitored periodically usinga UV–vis spectrophotometer (Shimadzu 4520) at a wave￾length in between 300 to 600 nm. The characteristic plasmonresonance peak of monodispersed AgNPs appeared around ~420 nm. The morphology and size of the AgNPs were ob￾served under a JEOL JEM-1400. High-resolution transmis￾sion electron microscopy (HRTEM) operated at 200 KVequipped with Olympus Soft Imaging Solutions GmbH (soft￾ware: iTEM; TEM Camera: Morada 4008 × 2672-pixel max)recording system. For HRTEM analysis, the samples wereprepared by placing one drop of the colloidal solution on acarbon-coated grid and dried at ambient temperature. Energy￾dispersive X-ray spectroscopy (EDAX) studies were also car￾ried out in parallel to find evidence for the presence of Ag innanoparticles. The structural morphology of the bacteria wasstudied using STEREOSCAN 360 (Cambridge scientific in￾dustries) scanning electron microscope (SEM), with goldcoating.