Green synthesis of silver nanoparticles using aganonerion polymorphum leaves extract and evaluation of their antibacterial and catalytic activity

Abstract

This study provides a fast, eco-friendly and low-cost method to synthesize stable colloidal solution of silver nanoparticles (AgNPs) using the extract of Aganonerion polymorphum (AP) leaves as a reducing and capping agent. Major parameters affecting the formation of biosynthesized AgNPs including AP leaf/water ratio, reaction time, temperature and pH were optimized at 60 g/4 00 ml, 10 min, 70 °C and 8, respectively. The AgNPs synthesized at these optimum parameters were carefully characterized using transmission electron microscopy (TEM), dynamic light scattering (DLS), powder x-ray diffraction (XRD), dispersive x-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) techniques. TEM and DLS analysis revealed that the synthesized AgNPs were formed in multi-shapes with an average size of about 30 nm. Besides, XRD data showed a highly crystalline face-centered cubic structure of silver, while EDS spectra contained strong characteristic signals of silver element. Especially, the biosynthesized AgNPs demonstrated a good antibacterial ability toward E. coli and B. cereus after just one hour of exposure with high destroying efficiency up to 99.94% and 99.75%, respectively. It’s also been found that the biosynthesized AgNPs have a good catalytic activity for the reduction of 4-nitrophenol into 4-aminophenol by NaBH4 in accordance with a pseudo first-order rate constant of 0.31 min−1.