doi:10.1038/nindia.2008.207 Published online 21 May 2008
Indian researchers have found an environment-friendly way to mass-produce silver nanoparticles. The researchers from Gulbarga University have used a marshland fungus to churn out the nanoparticles. With no toxic chemicals employed, this process may meet the future demands of silver nanoparticles, widely used in catalysis, biosensors and coatings for medical devices.
It is cumbersome and expensive to recover nanoparticles through extracellular synthesis. To overcome this, the researchers used the fungi Fusarium semitectum from marshlands in the extracellular synthesis of silver nanoparticles.
The fungus was grown in culture medium, its biomass sieved and washed and filtrate made to react with silver nitrate solution. In a day's time, the colour of the solution turned from colourless to brown indicating the formation of silver nanoparticles. The silver ions were reduced to silver nanoparticles in the solution.
The nanoparticles are spherical in shape with sizes between 10 and 60 nm. The nanoparticles were found to be stable even after 6-8 weeks of their formation. The proteins secreted from the fungus probably form a coat covering the metal particles to prevent clumping and stabilize them in solution.
"The benefit of the method is that the entire process is carried out at room temperature with very minimum equipment involved," says lead researcher Abbaraju Venkataraman. Chemical synthesis of nanoparticles may produce undesired toxic chemicals, which may get adsorbed on to their surface resulting in adverse effects in medical applications, he says. Synthesis of nanoparticles from microorganisms or plant can eliminate this problem enhancing biocompatibility, he concludes.