GREEN SYNTHESIS OF SILVER AND SILVER OXIDE NANOPARTICLES FROM CEDRUS LIBANI: BIOLOGICAL ACTIVITY AND INFLUENCE OF FILM THICKNESS ON OPTICAL PROPERTIES

Silver and silver oxide nanoparticles (Ag/AgO-NPs) exhibit remarkable optical and antibacterial properties, making them valuable for a range of industrial and biomedical applications.Synthesis and characterization of Ag/AgO-NPs extracted from Cedrus libani leaves with an emphasis on film thickness effects (100, 200, and 300 nm) are reported in this study.The nanoparticles were characterized using photoluminescence (PL), X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR).PL spectra exhibited emission peaks around 400 nm, which are implications of surface defects and phytochemical stabilization.FTIR confirmed the reduction and capping of functional groups, while TEM indicated an average particle size of 20.38 nm (range: 10-40 nm).The peaks at 38.05°, 44.25°, and 64.35° indicate face-centered cubic Ag/AgO NPs, as confirmed by XRD analysis.There was also over 90% transmittance at 1000 nm and above, as well as film thickness-dependent band gaps of 1.22-1.27eV.Biological assays indicated substantial antibacterial, antioxidant, and antibiofilm activity.Ag/AgO-NPs had minimum inhibitory concentrations of 0.375 mg/mL and minimum bactericidal concentrations of 0.75 mg/mL against S. aureus and E. coli.The time-kill test showed complete growth inhibition after 24 hours.There was also approximately 41% biofilm inhibition at approximately the subdoses, and a maximum of 70% of preformed biofilms were killed.Antioxidant activity was assessed.The results showed 59.68% and 77.5% radical scavenging at 100 and 200 µg/mL, respectively.Thus, Ag/AgO-NPs derived from Cedrus libani exhibit antimicrobial, antibiofilm, and antioxidant activities, highlighting their promise for both photonic and biomedical applications.