Plant-Mediated Synthesis of Silver Nanoparticles and Their Stabilization by Wet Stirred Media Milling

Matej Baláž,Yaroslav Shpotyuk,Ľudmila Balážová,Zdenka Bujňáková,Nina Daneu,Erika Dutková,Miriama Balážová

doi:10.1186/s11671-017-1860-z

Abstract

Within this study, a stable nanosuspension of silver nanoparticles (Ag NPs) was prepared using a two-step synthesis and stabilization approach. The Ag NPs were synthesized from a silver nitrate solution using the Origanum vulgare L. plant extract as the reducing agent. The formation of nanoparticles was finished upon 15 min, and subsequently, stabilization by polyvinylpyrrolidone (PVP) using wet stirred media milling was applied. UV-Vis spectra have shown a maximum at 445 nm, corresponding to the formation of spherical Ag NPs. Infrared spectroscopy was used to examine the interaction between Ag NPs and the capping agents. TEM study has shown the formation of Ag NPs with two different average sizes (38 ± 10 nm and 7 ± 3 nm) after the plant-mediated synthesis, both randomly distributed within the organic matrix. During milling in PVP, the clusters of Ag NPs were destroyed, the Ag NPs were fractionized and embedded in PVP. The nanosuspensions of PVP-capped Ag NPs were stable for more than 26 weeks, whereas for the non-stabilized nanosuspensions, only short-term stability for about 1 week was documented.

Highlights

Silver nanoparticles are in the spotlight of researchers these days [1, 2]
Preparation Plant-Mediated Synthesis of Ag NPs (Ag/O. vulgare L. Water Extract (ORE)) The course of the Ag nanoparticle synthesis was observed by the measurement of the Vis spectra, which were taken every minute during the synthesis (Fig. 1)
The Vis spectra show that almost immediately after the mixing of O. vulgare L. water extract and AgNO3 solution, the absorbance at 445 nm appears

Summary

Introduction

Silver nanoparticles are in the spotlight of researchers these days [1, 2]. Their multidisciplinary application is generally known [3], their utilization as antibacterial agents is probably the most widely studied [4, 5].There are various synthetic methods to obtain silver NPs [6], e.g., laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods [7]. Silver nanoparticles are in the spotlight of researchers these days [1, 2]. Their multidisciplinary application is generally known [3], their utilization as antibacterial agents is probably the most widely studied [4, 5]. There are various synthetic methods to obtain silver NPs [6], e.g., laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods [7]. Regarding the silver precursors for the Ag NPs synthesis, most often silver nitrate is used, as it is inexpensive and well accessible. A reducing agent has to be applied in order to transform silver from ionic to elemental form. In the so-called green approach, the reduction procedure is performed by a natural-based material, most commonly a plant extract containing substances with the reducing properties.

Methods

Results

Conclusion