Green biosynthesis of silver nanoparticles using Azolla pinnata whole plant hydroalcoholic extract

Abstract

The objectives were to study the potential of Azolla pinnata whole plant in green synthesis of nanoparticles (NPs), and the effect of the extract ethanol concentration on the produced NPs. A. pinnata whole plants were freshly collected, air dried at room temperature, powdered and sieved. Hydroalcoholic extracts (70% and 96%) were prepared by percolation of the plant powder. The reaction mixtures contained (final concentrations): AgNO3 (1 mm) as the substrate, plant extract as the biocatalyst and phosphate buffer (pH=7, 100 mm) as the reaction medium. The aforementioned ingredients were added in appropriate volumes into Duran bottles and were incubated at room temperature. Silver ions were determined using atomic absorption analysis. Samples for transmission electron microscopy (TEM) were prepared by drop-coating the silver NP suspensions onto carbon-coated copper grids. Particle size distribution of NPs was analyzed using Nano-Zeta Sizer. Hydroalcoholic extract (96%) of A. pinnata successfully produced quite small (as small as 0.93 nm and a mean size of 6.5 nm), spherical, and polydispersed silver NPs with low aggregates in the early hours of the biotransformation. The conversion was fast and complete in 5 h. Therefore, this plant and extraction method seems to be attractive for industrial scale production of NPs.

Keywords

• azolla pinnata
• green synthesis
• hydroalcoholic extract
• nanoparticle synthesis
• silver nps