Evaluation of the Effect of the Size of Ramalina fraxinea Based Ag NPs on the Antimicrobial Activity.

For the first time in this study, the effect of nanoparticles (NP) sizes on the antimicrobial activity of Ag NPs of different sizes obtained by the reaction of Ramalina fraxinea(R. fraxinea) extract and silver nitrate (AgNO3) at different concentrations was evaluated. For this purpose, characteristic light absorption points, and charge of the surface were determined by ultraviolet-visible spectroscopy (UV-Vis), and zeta potential, hydrodynamic diameters by dynamic light scattering (DLS) analysis, morphology, and diameters of NPs were determined by scanning electron microscope (SEM) analysis. The crystal structures of Ag NPs were confirmed by the X-ray diffraction (XRD) analysis map. The functional groups of the R. fraxinea extract, which plays an active role in the synthesis of Ag NP, were revealed by the peaks obtained by Fourier transform infrared spectroscopy (FT-IR) analysis. As a result of the characterization tests, the average diameter of Ag NPs increased from 14 nm to 48 nm with the increase in Ag NO3 concentration used in the synthesis of Ag NP (from 10-3 M to 5*10-2 M). The antimicrobial activity of Ag NPs against Staphylococcus aureus, Escherichia coli, and Candida albicans strains was evaluated depending on the size of the NPs. The antimicrobial effect of small-sized Ag NPs against the studied strains was quite effective compared to large-sized Ag NPs. As a result, it is seen that Ag NPs synthesized by using R. fraxinea extract in different sizes with a biologically inexpensive and eco-friendly method exhibit antimicrobial activity depending on the size. It is thought that the study data will be a guide for nanotechnology and biomedical field studies. [ABSTRACT FROM AUTHOR]