In vitro Evaluation of Antioxidant and Antibacterial Activities of Eco-friendly Synthesized Silver Nanoparticles using Quercus robur Bark Extract.

AIMS: This study reports a simple, cost-effective, and environmentally friendly method to obtain silver nanoparticles (AgNPs) using an aqueous extract of Quercus robur bark. METHODS: AgNPs synthesis conditions such as silver nitrate concentration, extract:AgNO3 volume ratio, pH, temperature, and reaction time have been examined. After optimizing the synthesis, the obtained AgNPs were characterized by different methods such as UV-Vis, TEM, EDX, and FTIR. The antioxidant activity was evaluated using lipoxygenase inhibition capacity and inhibition of erythrocyte hemolysis mediated by peroxyl free radicals tests. The antimicrobial potential of the samples was tested against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. RESULTS: The AgNPs synthesis process is influenced by reaction conditions, the optimum established values being, in this case: concentration of 3 mM AgNO3, 1:9 extract: AgNO3 volume ratio, pH value of 6, 60 ºC temperature, and 90 minutes stirring time. The shape of the synthesized AgNPs was predominantly spherical, with an average size of 50 nm. The SPR band at 432 nm, the strong EDX signal at ~ 3 keV and the zeta potential of -13.88 mV revealed the formation of AgNPs and electrostatic stabilization of the colloidal solution. FTIR analysis confirmed the participation of molecules from the extract in the synthesis and stabilization of AgNPs. The obtained nanoparticles showed improved antioxidant, antifungal and antibacterial activities compared to the extract. CONCLUSION: The results open the possibility of exploring new applications of nanoparticles obtained via green synthesis.

Green Synthesis and Characterization of Silver Nanoparticles Using a Lythrum salicaria Extract and In Vitro Exploration of Their Biological Activities.

This research describes an eco-friendly green route for the synthesis of AgNPs using an aqueous extract of Lythrum salicaria. Taguchi design was used to optimize the synthesis method, taking into account various working conditions. The optimum parameters were established using a 3 mM AgNO3 concentration, a 1:9 extract:AgNO3 volume ratio, a pH value of 8, 60 ℃ temperature, and 180 min reaction time. The synthesized AgNPs were characterized using UV-Vis and FTIR spectroscopy, and TEM and EDX analysis. The SPR band at 410 nm, as well as the functional groups of biomolecules identified by FTIR and the EDX signals at ~3 keV, confirmed the synthesis of spherical AgNPs. The average AgNPs size was determined to be 40 nm, through TEM, and the zeta potential was -19.62 mV. The antimicrobial assay showed inhibition against S. aureus and C. albicans. Moreover, the results regarding the inhibition of lipoxygenase and of peroxyl radical-mediated hemolysis assays were promising and justify further antioxidant studies.