Phytosynthesis of silver nanoparticles using Zingiber officinale extract: evaluation of their catalytic and antibacterial activities

Aqueous extract of the rhizome of ginger (Zingiber officinale) has been used to prepare silver nanoparticles. The aqueous dispersion of as-synthesized silver nanoparticles was stable. Almost spherical particles having average diameter 5.28 +/- 1.29 nm along with few large aggregates have been revealed from transmission electron microscopic image. Evidence of the existence of such small nanoparticles has also been demonstrated by their UV-Vis spectral analysis where characteristic Surface Plasmon Resonance Band (SPR) of silver nanoparticles appeared at 432 nm. Cyclic voltammetry (CV) study was performed to know the reducing ability of the aqueous extract of the rhizome. The interaction of the ingredients present in the extract with the surface of nanoparticles was studied using FT-IR spectroscopy. Catalysis and antibacterial activity, two very important applications of such nanoparticles were studied. The silver nanoparticles exhibited antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Catalytic efficiency of the nanoparticles was evaluated and reported in terms of catalytic activity parameter (kappa), against the degradation of common environmental pollutants 4-nitrophenol (4-NP) and common organic dyes like Eosine blue (EB), Brilliant Cresyl Blue (BCB), Eriochrome Black T (EBT). The obtained kappa values are 549, 218, 1054, 280 s(-1) g(-1) for 4-NP, EB, BCB and EBT, respectively and some of these values are comparable with the values of kappa reported in literature suggesting the good catalytic efficiency of nanoparticles.