Environmentally green synthesis of stable polyvinyl pyrrolidone (PVP)-capped silver nanoparticles (PVP-AgNPs) was successfully carried out. The present study focused on investigating the influence of adding PVP during the synthesis process on the size, optical properties and antibacterial effect of silver nanoparticles produced. An aqueous extract of Eucalyptus camaldulensis leaves was used as a reducing agent. The effects of different PVP concentrations and reducing time on the synthesis of nanoparticles (NPs) were characterized by UV–Vis spectrophotometry, scanning electron microscopy (SEM), energy dispersive spectrum (EDX), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and nano tracker analysis (NTA). The addition of PVP was studied. The prepared PVP-AgNPs were spherical with an average size of 13 nm. FTIR analysis confirmed that PVP protects AgNPs by a coordination bond between silver nanoparticles and both N and O of PVP. DLS results indicated the good dispersion of silver nanoparticles. PVP-AgNPs were found to be stable for nearly 5 months. Antibacterial studies through the agar well diffusion method confirmed that silver nanoparticles synthesized using PVP had no inhibitor activity toward Gram-positive and Gram-negative bacteria as opposed to silver nanoparticles prepared without adding PVP, which showed a significant antibacterial activity towards some of the tested pathogens.

Ghmkin Hassan, Issam Kasem, Chadi Soukkarieh, Majd Aljamali. IJSC 2017;10:184-92. https://doi.org/10.15283/ijsc.2017.10.2.184

This study is one of the few studies that presents an ecofriendly procedure for biosynthesis of AgNPs via aqueous extract Eucalyptus camaldulensis leaves (AEECL). The main of current work was to ensure the ability of AEECL as reducing agent for synthesis of AgNPs. Characterization of AgNPs was carried out by UV-Vis, FTIR and XRD, SEM, EDX, DLS, and Zeta value. The surface Plasmon at 450 nm is the primary confirmation for the formation of Ag. Characterization studies by SEM found the synthesized AgNPs were spherical shape with size about 28 nm. The EDX analysis of the AgNPs confirmed strong signals for silver atoms. According XRD analysis, synthesis of Silver nanocrystals with size ∼16 nm was confirmed. The FT-IR study confirmed that the ECL extract acts both role as a reducing agent and a stabilizer of AgNPs. The DLS results confirmed the monodispersity of AgNPs with mean size of 68 nm.