Green Synthesis of Silver Nanoparticles with Dalbergialatifolia Plant Leaves as Reductant and Its Antimicrobial Properties

Abstract

Green synthesis of nanoparticles has evolved as a low-cost environment friendly, non-toxic and large scale up process. This investigation was carried out on the synthesis of AgNPs using Dalbergialatifolia (DL) aqueous plant leaves extract for the bioreduction of silver ions to nanoparticles, with AgNO3 as the precursor. The bioreduction process was carried out varying certain operational parameters; pH, reaction time, AgNO3 concentration and ratio of extract to silver nitrate solution. UV-Vis spectrophotometer was used to monitor the reaction. Characterization of the synthesized AgNPs was done using Ultravisible/Visible Spectrophotometer (Uv/Vis), Fourier Transform Infra-Red (FTIR), X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analyses. The surface plasmon resonance (SPR) band for the AgNPs was observed to be at 450nm. The optimum conditions for the synthesis of AgNPs with the plant extract were obtained to be; 45 minutes synthesis time, acidic pH, 1mM AgNO3 concentration and ratio 1:1 of plant extract to AgNO3 solution. FTIR analysis for the plant extract revealed the presence of O-H, C=O, C-H, C-N, N-H functional groups as well as the benzyl ring which are found in compounds like flavonoids, phenols and terpenoids. The characteristic peaks for these functional groups were also observed in the synthesized AgNPs, but had almost disappeared, which may indicate that these compounds, present in the plant extract were responsible for efficient reduction, capping and stabilization of the obtained AgNPs. SEM analysis revealed that the synthesized AgNPs were quassi spherical in shape and uniformly distributed. The XRD patterns of the AgNPs revealed Braggs reflections representing b111N, b200N, b220N and b311N planes for fc crystal structure for metallic silver with reference to the JCPDS data. Antimicrobial activity of the nanoparticles was studied against; Staphylococcusaureus, Esterichiacoli, Bacillussubtilus, Pseudomonasaeruginose, Klebsiella, Salmonellaetyphi, Candidaalbican, Aspergillusniger, Rhizophusstolomite and Penicilliumnotatum which in turn showed good inhibition against the microbes at both high and low concentrations. Dalbergialatifolia plant leaves extract proves to be a good option as reductant for AgNPs synthesis, and the synthesized AgNPs were found to be very effective antimicrobial agent.