Synthesis and Characterization of Silver Nanoparticles from Escherichia coli MTCC 118

This paper aims to report the synthesis and characterization of silver nanoparticles using the extract of Escherichia coli MTCC 118. The cell extract from this new strain is used for the first time for the synthesis of silver nanoparticles. This method of synthesis is a biological synthesis method by adding silver nitrate into the cell extract. This method is nontoxic, low cost and energy efficient compared to physical and chemical procedures [1]. Using the biological method, silver ions are bioreduced into silver nanoparticles from the cell extract of Escherichia coli MTCC 118. The formation of silver nanoparticles was then confirmed by indication of change in colour from colourless to reddish brown. This colour change was observed using UV-Vis Spectroscopy. UV-Visible spectrum of the aqueous medium containing silver ions was observed at the peak at 440-445nm corresponding to the surface plasmon absorbance of silver nanoparticles. The silver nanoparticles thus formed were further analyzed and characterized by FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction Analysis) and AFM (Atomic force Microscopy). The average diameter of the silver nanoparticles was found to be in the range of 93-170nm using AFM. Samples given for further characterization of size and morphology of silver nanoparticles using TEM (Transmission Electron Microscopy) and SEM (Scanning Electron Microscopy). Further the synthesized silver nanoparticles were tested against common bacterial pathogens. These biosynthesized silver nanoparticles may be used to develop a biosensor model for the detection of bacteria [2].