Biomimetic Synthesis of Silver Nanoparticles Using the Lichen Ramalina Dumeticola and the Antibacterial Activity

Silver nanoparticles (AgNPs) has been successfully synthesized by reduction of silver nitrate with an aqueous extract of the lichen Ramalina dumeticola. The aqueous extract of Ramalina dumeticola was treated with 45 mL of 1 mM silver nitrate at room temperature (24-25 degree Celsius) for 24 hours. The ultraviolet-visible (UV-Vis) absorption spectroscopy has been used to monitor the formation of AgNPs. Physical appearance of AgNPs characterized by transmission electron microscopy (TEM) showed formation of AgNPs with average particle size of 13 nm. X-ray diffraction (XRD) techniques displayed the AgNPs as cubic structure. The UV-Vis absorption spectroscopy results showed a strong resonance centered on the surface of AgNPs at approximately 433 nm. The in vitro antibacterial activity of the synthesized AgNPs was investigated against eight bacterial strains using a disc diffusion method and its showed inhibition against all of them. The results revealed that the above AgNPs have potential as antibacterial agent. (author)