Efficient and robust biofabrication of silver nanoparticles by cassia alata leaf extract and their antimicrobial activity

Biosynthesis of green nanomaterials and their characterization comprise an emerging field of nanotechnology, due to their wide range of applications. The present study deals with the synthesis of silver nanoparticles (AgNPs) using an aqueous leaf extract of Cassia alata. The AgNPs are characterized using UV–Visible spectroscopy. The surface plasmon resonance spectrum of AgNPs was obtained at 434 nm, and scanning electron microscopy coupled with X-ray energy dispersive spectroscopy (EDX) data revealed that AgNPs were uniformly spherical in shape. EDX data show very strong silver signal and weak signals to other elements, and X-ray diffraction patterns reveal that the particles are crystalline in nature with face-centered cubic structure. Fourier transform-infrared spectroscopy reveals that the carbonyl group (C = O, 1637.07 cm−1) is involved in the reduction of Ag+ to Ag. The synthesized AgNPs were crystalline in nature and spherical in shape, with an average of >41 nm size. The stability of AgNPs is due to its high negative zeta potential, which is –50.7 mV. Further, atomic force microscopy studies also revealed that the average particle size was 47 nm which correlates with the above result of particle size analysis. The present study also indicates that AgNPs have considerable antibacterial activity and exceptionally superior antifungal activity, in comparison with standard antimicrobial drugs. © 2014, The Author(s).