Akademik Veri Yönetim Sistemi
PLASMONICS, cilt.20, sa.11, ss.10691-10710, 2025 (SCI-Expanded, Scopus)
In this study, gold (Au) and silver (Ag) nanoparticles were synthesized from an aqueous solution of catechin extract obtained by sequential microwave extraction (MAE) and supercritical fluid extraction (SFE) for the first time at different temperatures (25, 35, 45 degrees C) in accordance with the characteristics of green chemistry. For the synthesis of Ag and Au nanoparticles at three different temperatures, 100 mL of an aqueous 1 mM AgNO3 solution was added to different volumes (0.5-4 mL) of catechin extract solutions. In the biosynthesis of Ag and Au nanoparticles, 1 mM AgNO3 solution and 0.5 mM HAuCl4.3H2O at 25 degrees C and 0.5 mL extract volume were determined as the best parameters. The crystalline structures of AgNP and AuNP nanoparticles synthesized using catechin extract in accordance with green chemistry principles were confirmed by X-ray diffraction (XRD) analysis. The average crystallite sizes were determined to be 18.82 nm for AgNPs and 14.31 nm for AuNPs. Transmission electron microscopy (TEM) revealed size distributions of 19.50 +/- 5.52 nm for AgNPs and 20.06 +/- 5.38 nm for AuNPs. Dynamic light scattering (DLS) analysis showed that the hydrodynamic diameters were 37.61 +/- 1.25 nm for AgNPs and 37.9 +/- 0.26 nm for AuNPs. The zeta potential values were measured as -20.4 mV for AgNPs and -22.6 mV for AuNPs. The PDI (polydispersity index) values were found to be 0.271 +/- 0.006 for AgNPs and 0.295 +/- 0.004 for AuNPs. The effects of various concentrations of AgNPs and AuNPs on DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity were determined. At a concentration of 0.91 mg/mL, AgNPs exhibited a high antioxidant activity of 89.24%, while AuNPs showed 70.46% activity at 2.677 mg/mL. In comparison, the standard antioxidant Trolox demonstrated 91.19% inhibition at a concentration of 0.012 mg/mL. The IC50 values of green-synthesized AgNPs, AuNPs, and standard Trolox were calculated as 1.151, 1.485, and 0.006 mg/mL, respectively. The results obtained from this study indicate that biologically synthesized AgNPs and AuNPs can be effectively used as potent antioxidants.