Biological synthesis of gold and silver nanoparticles mediated by the bacteria Bacillus subtilis.

Biological synthesis of gold and silver nanoparticles was carried out using the bacteria Bacillus subtilis. The reduction processes of chloroaurate and silver ions by B. subtilis were found to be different.

Synthesis of gold nanoparticles via an environmentally benign route using a biosurfactant.

Anionic biosurfactant surfactin-mediated gold nanoparticles were synthesized for the first time in this study. Differing proton concentrations is believed to cause structural changes in the lipopeptide surfactin used to stabilize the gold nanoparticles in aqueous solution, the effects of which on the morphology of the nanoparticles were investigated. Synthesis of gold nanoparticles by borohydrate reduction was performed at three pH levels (pH 5, 7 and 9) and two different temperatures, and the nanoparticles were characterized by UV-visible spectroscopy, X-ray diffraction and transmission electron microscopy.