Several studies have been shown that leaf extracts are responsible for the reduction of silver ions for the synthesis of silver nanoparticles. The absorption peak at 1,636 cm-1 is close to that reported for native proteins [36] which suggest that proteins are interacting with biosynthesized nanoparticles. It is well-known that proteins can bind to gold nanoparticles either through free amine groups or cysteine residues in the proteins [37]. A similar mechanism could be possible, the leaf extract from A. cobbe cap the silver nanoparticles, thereby stabilizing them. Similar FTIR pattern was also observed for synthesis of silver nanoparticles using Geranium leaf extract [38], selleck chemical Ocimum sanctum leaf extract [6, 26, 39]. Figure 3 FTIR
spectra of A. cobbe leaf broth (A), silver nanoparticles synthesized by A. cobbe leaf broth (B). XPS analysis of AgNPs X-ray photoelectron spectroscopy (XPS) was utilized to investigate the chemical state of the leaf extract-mediated synthesis of AgNPs. The quantitative Ag/C atomic ratios of the samples RGFP966 were determined using the peak area ratio of the corresponding XPS core levels and the sensitivity factor (SF) of each element in XPS. Figure 4 shows high-resolution XPS
spectra of the C(1 s) core level for the AgNPs. The binding energies of Ag(3d5/2) and Ag(3d3/2) peaks were found at binding energies of 368.0 and 374.0 eV, respectively. To further understand the chemical state of the AgNPs on the surface, a detailed deconvolution of the Ag(3d) peak was also performed. The binding energy of the Ag(3d5/2) core level for Ag, Ag2O, and AgO is 368.5, 368.3, and 367.7 eV, respectively. Based on the Ag(3d5/2) peak analysis, we have found that about
93% of the silver atoms on the surface were in the Ag0 (metallic) state, while only about 1% and 6% of the silver atoms were in the Ag+ and Ag2+ chemical states, respectively. These values are in good agreement with published values for AgNPs. Figure 4 XPS analysis of AgNPs. Particle size distribution analysis of AgNPs TEM images are captured under high vacuum conditions with a dry sample; Thymidylate synthase before analysis of AgNPs using TEM, dynamic light scattering (DLS) was carried out to determine particle size in aqueous solutions using DLS. The characterization of nanoparticles in solution is essential before assessing the in vitro toxicity [40]. Particle size, size distribution, particle morphology, particle composition, surface area, surface chemistry, and particle reactivity in solution are important factors in assessing nanoparticle toxicity [40]. DLS is a valuable technique to evaluate particle size, and size distribution of nanomaterials in solution. In the present study, DLS was used, in conjunction with TEM, to evaluate the size distribution of AgNPs. The AgNPs showed with an average size of 5 nm, which exactly matches with TEM observation (Figure 5). The DLS pattern revealed that leaf extract-mediated synthesized AgNPs showed with an average size of 5 ± 4 nm. Singhal et al.