Microwave Aided Synthesis of Silver and Gold Nanoparticles and their Antioxidant, Antimicrobial and Catalytic Potentials

Abstract

Here we reported the extremely simple one-pot synthesis of silver and gold nanoparticles in a rapid manner. Aqueous leaf extract of the most admired energy plant Jatropha curcas is used as reducing agent here. An alternate and safe energy source, house-hold microwave oven constituted the reaction chamber. Silver and gold nanoparticles were characterized by UV-visible, FT-IR, Powder XRD techniques. Surface plasmon resonance peaks corresponding to silver and gold nanoparticles were 428 nm and 543 nm respectively. The XRD patterns were indexed to reflections originated from (111), (200), (220) and (311) faces of FCC nanosilver and nanogold. Microscopic analysis revealed spherical geometry of silver nanoparticles with an average diameter 20.42±12.2 nm. Gold nanometals exhibited uneven shapes with average size 17.12±2.9 nm. In-vitro antioxidant potential assessment by DPPH model gave IC50 values 19.37±0.63 and 16.59±0.29 µg/ mL for silver and gold nanoparticles. The nanometals showed excellent bactericidal activity in agar well diffusion towards microorganisms namely Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus nidulans and Aspergillus flavus. Degradation of methylene blue and rhodamine B by NaBH4 happened within 10 minutes in the catalytic presence of silver/gold nanoparticles offered a new means for purification of industrial dye effluents. Hydrogenation of 4-nitrophenol in presence of the prepared nanoparticles validated their catalytic utility. The reaction followed pseudo-first order kinetics with respect to reactant concentration.