Fungus Mediated Intra- and Extra-Cellular Synthesis of Gold Nanoparticles: a Novel Biological Approach to Nanoparticle Synthesis

Absar Ahmad1, Priyabrata Mukherjee2, Deendayal Mandal2, Satyajyoti Senapati2, Mohammad I. Khan1, Murali Sastry3, and Rajiv Kumar2

1Biochemical Sciences, 2Catalysis, and 3Materials Chemistry Divisions, National Chemical Laboratory, Pune-411 008, Maharashtra, India




Development of green chemistry protocols for the synthesis of inorganic nanoparticles is a problem of topical interest in nanotechnology. In this paper, we report on the development of a new biological method for the synthesis of gold nanoparticles using fungi. Exposure of the fungal biomass to aqueous AuCl4- ions results in either the intracellular or extra-cellular reduction of the metal ions depending on whether the fungus used is Verticillium or Fusarium oxysporum respectively. The gold nanoparticles exhibit tolerable monodispersity (size in the range 5-20 nm) and in the case of particles synthesized extra-cellularly, excellent long term stability as well. The reduction of the metal ions is believed to occur through an enzymatic process thus opening up the exciting possibility of extending the fungal-based method to the synthesis of nanoparticles over a range of chemical compositions in a rational manner. The metal ions were not toxic to the fungal cells and they continued to multiply after biosynthesis of the gold nanoparticles.