Bio-conjugated silver nanoparticles: From Ocimum sanctum and role of cetyltrimethyl ammonium bromide

In this paper we have reported the spectrophotometeric and transmission electron microscopic (TEM) data to the shape-directing role of cetyltrimethylammonium bromide (CTAB) on the green extra-cellular synthesis of bio-conjugated Ag-nanoparticles using Ocimum sanctum leaves extract. TEM images revealed that the nanoparticles are mostly spherical (average particle size ranged from 18 to 35 nm) with some truncated triangular nanoplates, aggregated in a beautiful manner to yield locket-like silver and capped by a thin layer of biomolecules of O. sanctum, whereas nanoparticles are highly poly-dispersed in presence of CTAB. The shape and position of wavelength maxima strongly depends on the reaction time, [leaves extract] and [CTAB]. The visual observations also suggest that the prefect transparent silver sol becomes turbid in presence of CTAB after some time.

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► Ocimum sanctum (medicinal aromatic plant) leaves extract used as a greener reducing agent for the extracellular synthesis of bio-conjugated advanced nano silver.
► Morphology of the silver nanoparticles strongly depends on the nature of stabilizer.
► Faint thin layer of other material was visualized on the surface nanoparticles which might be due to the capping organic material of ocimum leaf broth.