Shape-directing role of cetyltrimethylammonium bromide on the morphology of extracellular synthesis of silver nanoparticles

Oriental plane leaf extracts were used as a reducing-, stabilizing- and capping-agent for the preparation of silver nanoparticles (AgNPs) for the first time. The size, shape, size distribution and optical properties strongly depend on the experimental conditions, absence, and presence of shape-directing cetyltrimethylammonium bromide (CTAB). UV–vis spectroscopy, transmission electron microscopy and selected electron diffraction ring patterns were used to determine the morphology of resulting AgNPs at different time intervals. The spectra showed a surface Plasmon resonance (SPR) peak at 450 nm which is the characteristic of spherical AgNPs (diameter ranging from 10 to 30 nm). The peak shifted to shorter wavelength (blue shift) from 450 to 425 nm and sharpness of the peak also decreases in the presence of CTAB which might be due to the capping action of CTAB. A layer of ca. 3 nm around a group of the AgNPs in which the inner layer is bound to the AgNPs surface via the active groups of the extract has been observed.