Green synthesis of highly stabilized nanocrystalline silver particles by a non-pathogenic and agriculturally important fungus T. asperellum

• Published in: Nanotechnology Vol. 19; no. 7; p. 075103
• Main Authors: Mukherjee, P, Roy, M, Mandal, B P, Dey, G K, Mukherjee, P K, Ghatak, J, Tyagi, A K, Kale, S P
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 20.02.2008
• ISSN: 0957-4484; 1361-6528
• DOI: 10.1088/0957-4484/19/7/075103

A controlled and up-scalable biosynthetic route to nanocrystalline silver particles with well-defined morphology using cell-free aqueous filtrate of a non-pathogenic and commercially viable biocontrol agent Trichoderma asperellum is being reported for the first time. A transparent solution of the cell-free filtrate of Trichoderma asperellum containing 1 mM AgNO(3) turns progressively dark brown within 5 d of incubation at 25 °C. The kinetics of the reaction was studied using UV-vis spectroscopy. An intense surface plasmon resonance band at ∼410 nm in the UV-vis spectrum clearly reveals the formation of silver nanoparticles. The size of the silver particles using TEM and XRD studies is found to be in the range 13-18 nm. These nanoparticles are found to be highly stable and even after prolonged storage for over 6 months they do not show significant aggregation. A plausible mechanism behind the formation of silver nanoparticles and their stabilization via capping has been investigated using FTIR and surface-enhanced resonance Raman spectroscopy.