Abstract

GREEN SYNTHESIS OF GOLD NANOPARTICLES USING CASSIA ALATA LEAF EXTRACT AND EVALUATION OF ANTIMICROBIAL ACTIVITIES

Le Thi Thanh, Thejesh Kumar M. P. and Rajkumar H. Garampalli*

Abstract

In present study gold nanoparticles with average particle size of 12.3 nm was synthesized by an easy, simple and ecofriendly method using leaf extract of Cassia alata. The synthesis of gold nanoparticles was primarily confirmed by visible colour change of reaction mixture from yellowish to purple /wine red colour and intense peak at λ-max 539 nm due to surface plasmon resonance arising by the collective oscillation of conduction electron on the particle surface. Further the synthesized particles were characterized for structure, size, and possible biomolecules responsible for synthesis, elemental composition and presence of elemental gold by XRD, SEM, FTIR and EDAX respectively. Synthesized gold nanoparticles were proved to be effective against pathogenic bacteria and phyto-pathogenic fungi. Bacillus subtilis and Escherichia coli both found to be more susceptible to gold nanoparticles with 13.33 mm of inhibition. Phytopathogenic Aspergillus flavus was found to be more susceptible with 53.11% inhibition followed by Didymella bryoniae (50.07 % inhibition) and Fusarium oxysporum (41.92 % inhibition) respectively.

Keywords: Green synthesis, gold, nanoparticles, Cassia alata, antimicrobial activity.