Abstract
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.
Highlights
Silver nanoparticles (AgNPs) are characterized by being at least one dimension smaller than 100 nm and having a high surface area to volume ratio
The results clearly showed that AgNPs induced significant accumulation of cells in prophase (85.17 ± 0.77% and 84.32 ± 2.60% for Picea abies and Pinus nigra bark extract derived AgNPs, respectively) in comparison with the bark extracts (75.31 ± 2.32% and 67.40 ± 0.64% for Picea abies and Pinus nigra bark extracts, respectively) and control (53.80 ± 2.90%)
Polyphenols were found to be majorly involved in the synthesis and stabilization of AgNPs but ATR-FTIR and Raman spectroscopic data clearly indicated the contribution of other compounds in bark extracts
Summary
Silver nanoparticles (AgNPs) are characterized by being at least one dimension smaller than 100 nm and having a high surface area to volume ratio. AgNPs can be produced by physical (evaporation and condensation, laser ablation, spray pyrolysis), chemical (chemical reduction, electromagnetic radiation, and electrochemical cell methods), biological (plant extract and microbial reduction) and mechanical (ball milling) methods [1,2]. Both physical and chemical methods have several drawbacks, such as high energy consumption, expensive equipment, long reaction time, use of toxic chemicals and generation of chemical wastes (unreacted chemicals) which have to be discarded [1]. Plant extracts act as reducing and/or capping agents, and as modulators of the biological effects of nanosized metallic Ag [5]. AgNPs synthesized using plant extracts or pure phytochemicals have been reported to develop a wide range of biological activities, such as antibacterial, antifungal and antiviral [6], anti-inflammatory [7], antioxidant [5,7], wound healing [8], anticancer [1,3], anticoagulant [9], cardioprotective [10], liver protective [10], antidiabetic [11], anti-cataractogenic [12] and anti-ageing [13] activities
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