Biosynthesis of Silver Nanoparticles by Aspergillus niger

The role of nanomaterials in building future technology is immense and its application in a plethora of fields makes it interesting to explore more in this area. An important aspect of nanotechnology concerns the development of experimentally reliable protocols for the synthesis of nanoparticles. An attractive perspective would be the use of microorganisms to synthesize nanoparticles. Extracellular synthesis of silver nanoparticles by Aspergillus niger was carried out under varying concentrations of glucose in the medium. It was found that the A. niger reduced silver nitrate to silver nanoparticles in solution by a shuttle quinone extracellular process. The HPTLC (High performance thin layer chromatography) analysis of the filtrate obtained by filtering the biomass in milli-Q water on silica gel 60 plates using Ethyl acetate- Methanol- Water (100:13.5:10) showed a spot with Rf value of 0.65 corresponding to 2-acetyl-3,8- dihydroxy-6-methoxy anthraquinone or its isomers. Also, the maximum yield of silver nanoparticles was obtained at glucose concentration of 2.75g/l. This is the first time that the biosynthesis of silver nanoparticles by A. niger is reported and the potentialities of this nanotechnological design are vast including anti-cancer and anti-bacterial activities.