A safe, efficient and environment friendly biosynthesis of silver nanoparticles using Leucaena leucocephala seed extract and its antioxidant, antimicrobial, antifungal activities and potential in sensing

One step green synthesis of silver nanoparticles (AgNPs) from silver nitrate (AgNO3) using Leucaena leucocephala seeds extract as the reducing agent at room temperature was performed. The bioreduced NPs were characterized by UV-vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) coupled with energy dispersive spectrophotometry, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) techniques. Qualitative information of major components in the seed extract was obtained through its phytochemical screening. The phytochemical data of L. leucocephala revealed the presence of terpenes, flavonoids, coumarins and sterols. The reaction was optimized for AgNO3, extract concentration and time duration for the reaction. The obtained NPs showed a characteristic UV peak of AgNPs at 420 nm. TEM and SEM images showed the spherical shaped NPs over which the extract coating was very prominent. The binding of L. leucocephala seeds extract onto NPs was tested using FTIR and TGA. The antifungal activity of the as-synthesized NPs against two fungal species, namely Phlebiopsis gigantea and Echinodontium taxodii, was studied. The antimicrobial effect of the as-synthesized NPs was ascertained against Escherichia coli and Staphylococcus aureus. The antioxidant potential of the AgNPs was tested with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. Also, the sensitivity of the NPs towards Fe3+ ions was tested in aqueous media.