Antibacterial activity of silver nanoparticles synthesized using Amaranthus viridis twig extract

Abstract

Development of nano biotechnology is generating interest of researchers toward ecofriendly, cost effective and biological synthesis of nanoparticles. In this study, synthesis of stable silver nanoparticles was done using Amaranthus viridis twig extract. These rapid biological synthesized silver nanoparticles were characterized with the help of UV–Vis spectrophotometer, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy-Energy dispersive spectroscopy (SEM-EDX), Transmission Electron Microscopy (TEM) and X-Ray diffraction spectroscopy (XRD). Stability of reduced silver nanoparticles was analyzed using UV–Vis spectra shown that the absorption peak, occurring due to Surface Plasmon Resonance (SPR), exists at 423.5nm and their antibacterial activity was screened against both gram-negative and gram-positive bacteria. It was observed that Amaranthus viridis twig extract reduced silver ions into silver nanoparticles within 10 min of time. Thus, this method is rapid and eco- friendly. The TEM and SEM analysis inferred that the rapid biologically synthesized silver nanoparticles are spherical in shape and have an average size of 5-20nm. The antibacterial activity of silver nanoparticles against both gram positive and gram negative bacteria was performed in Luria–Bertani (LB) medium on solid agar plates and in liquid systems supplemented with different concentrations of nano-sized silver particles. These particles were shown to be an effective bactericide. Test for protein and nucleic acids leakage were performed to study the bio- cidal action of this nano sized particles. The results confirmed that the treated bacterial cells were damaged, showing leakage of proteins and nucleic acids into LB media. These nanoparticles, which can be prepared in a simple, rapid and cost-effective manner, are suitable for the formulation of new types of bactericidal materials.