Phyto-Functionalized Silver Nanoparticles Derived from Conifer Bark Extracts and Evaluation of Their Antimicrobial and Cytogenotoxic Effects

Silver nanoparticles synthesized using plant extracts as reducing and capping agents showed various biological activities. In the present study, colloidal silver nanoparticle solutions were produced from the aqueous extracts of Picea abies and Pinus nigra bark. The phenolic profile of bark extracts was analyzed by liquid chromatography coupled to mass spectrometry. The synthesis of silver nanoparticles was monitored using UV-Vis spectroscopy by measuring the Surface Plasmon Resonance band. Silver nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, Raman spectroscopy, dynamic light scattering, scanning electron microscopy, energy dispersive X-ray and transmission electron microscopy analyses. The antimicrobial and cytogenotoxic effects of silver nanoparticles were evaluated by disk diffusion and Allium cepa assays, respectively. Picea abies and Pinus nigra bark extract derived silver nanoparticles were spherical (mean hydrodynamic diameters of 78.48 and 77.66 nm, respectively) and well dispersed, having a narrow particle size distribution (polydispersity index values of 0.334 and 0.224, respectively) and good stability (zeta potential values of -10.8 and -14.6 mV, respectively). Silver nanoparticles showed stronger antibacterial, antifungal, and antimitotic effects than the bark extracts used for their synthesis. Silver nanoparticles obtained in the present study are promising candidates for the development of novel formulations with various therapeutic applications.