pH dependant fungal proteins in the ‘green’ synthesis of gold nanoparticles

An efficient, simple and environment friendly biosynthesis of gold nanoparticles (GNPs), mediated by fungal proteins of Coriolus versicolor is reported. By altering the reaction conditions, the intracellular synthesis of GNPs on the fungal mycelium, could be well tailored to produce extracellular GNPs in the aqueous medium. The reaction rate and the morphology of the particles were found to depend on parameters such as pH, incubation temperature and concentration of gold solution. The gold nanoparticles were characterized by UV–Vis, SEM and AFM techniques, demonstrating high stability of gold nanoparticles in aqueous media, via the protein layer. The size of the gold nanoparticles using AFM studies was found to be in the range 5–30 nm. These nanoparticles were found to be highly stable as even after prolonged storage for over 6 months they do not show aggregation. A plausible mechanism explaining the role of different possible proteins under different conditions, in the formation of gold nanoparticles has been investigated using FTIR. This study represents an important advancement in the use of fungal protein for the extracellular synthesis of functional gold nanoparticles by a green and mild technique in one pot. Copyright © 2010 VBRI press.