Biofabrication of Silver Nanoparticles by Opuntia ficus-indica: In vitro Antibacterial Activity and Study of the Mechanism Involved in the Synthesis

We report Opuntia ficus-indica mediated synthesis of colloidal silver nanoparticles. Detection and characterization of nanoparticles were carried out by UV-Vis- and Fourier Transform Infra Red Spectroscopy, Scanning Electron Microscopy and X-ray Diffraction analysis respectively. The aim of the present study was synthesis of silver nanoparticles, assessment of their antibacterial activity, and study of possible mechanism involved. The silver nanoparticles in combination with commercially available antibiotics showed a remarkable antibacterial activity. Some of the commercially available antibiotics in combination with silver nanoparticles showed remarkable activity. However, the maximum activity was demonstrated by Ampicillin followed by Streptomycin and Vancomycin. On the basis of the information obtained in this work, two-step mechanism has been proposed as bioreduction and formation of an intermediate complex leading to formation of capped nanoparticles.