Biological activity of green-synthesized silver nanoparticles depends on the applied natural extracts: a comprehensive study

Abstract

Andrea Rónavári,1,* Dávid Kovács,2,* Nóra Igaz,2,* Csaba Vágvölgyi,3 Imre Miklós Boros,2,4 Zoltán Kónya,1,5 Ilona Pfeiffer,3 Mónika Kiricsi2 1Department of Applied and Environmental Chemistry, 2Department of Biochemistry and Molecular Biology, 3Department of Microbiology, University of Szeged, 4Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, 5MTA-SZTE Reaction Kinetics and Surface Chemistry Research Group, Szeged, Hungary *These authors contributed equally to this work Abstract: Due to obvious disadvantages of the classical chemical methods, green synthesis of metallic nanoparticles has attracted tremendous attention in recent years. Numerous environmentally benign synthesis methods have been developed yielding nanoparticles via low-cost, eco-friendly, and simple approaches. In this study, our aim was to determine the suitability of coffee and green tea extracts in green synthesis of silver nanoparticles as well as to compare the performance of the obtained materials in different biological systems. We successfully produced silver nanoparticles (C-AgNP and GT-AgNP) using coffee and green tea extracts; moreover, based on our comprehensive screening, we delineated major differences in the biological activity of C-AgNPs and GT-AgNPs. Our results indicate that although GT-AgNPs exhibited excellent antimicrobial activity against all the examined microbial pathogens, these particles were also highly toxic to mammalian cells, which limits their potential applications. On the contrary, C-AgNPs manifested substantial inhibitory action on the tested microbes but were nontoxic to human and mouse cells, indicating an outstanding capacity to discriminate between potential pathogens and mammalian cells. These results clearly show that the various green materials used for stabilization and for reduction of metal ions have a defining role in determining and fine-tuning the biological activity of the obtained nanoparticles. Keywords: green synthesis, silver nanoparticles, antimicrobial activity, toxicity

Keywords

• green synthesis
• silver nanoparticles
• antimicrobial activity
• toxicity