Green synthesis of assembled silver nanoparticles in nano capsules of Peganum harmala L leaf extract. Antibacterial activity and conjugate investigation

Abstract There are a lot of publications concerning with biosynthesis of well-separated silver nanoparticles (AgNPs) from the aqueous plant extracted lower molecular weight polyol. In this first investigation, Ph.L leaf and seed extract broths were used for “green” synthesis of assembled and well-separated AgNPs, comparatively. AgNP formation from Ag (I) ions was determined by both extract color changes, UV-Vis absorption spectra, and surface plasmon resonance (SPR). The size, size distribution, and elemental and crystalline state of the formed AgNPs were determined by electron microscopy and spectrometry. The obtained results revealed the formation of assembled poly-dispersive spherical AgNPs of size measured 52.6 nm (leaf broth) and well-separated 24.2 nm (seed broth) on average. AgNPs assembled inside diffusible nano-capsules formed from the extracted macromolecules in case of leaf extract broth. Both extracts exhibited good AgNP-protecting active ingredients according to their binding affinity to L-lysine functional groups. Further, these diffusible AgNPs exerted good and comparable antibacterial activity against Staphylococcus aureus and Escherichia coli pathogens. Our results draw attention about assembling or growth of NPs by aqueous plant extracted polyol macromolecules as simple experimental protocol.