Application of Silver Nanostructures Synthesized by Cold Atmospheric Pressure Plasma for Inactivation of Bacterial Phytopathogens from the Genera Dickeya and Pectobacterium.

Anna Dzimitrowicz,Weronika Babinska,Wojciech Sledz,Agata Motyka,Piotr Jamroz,Ewa Lojkowska,Dominik Terefinko,Pawel Pohl

doi:10.3390/ma11030331

Abstract

Pectinolytic bacteria are responsible for significant economic losses by causing diseases on numerous plants. New methods are required to control and limit their spread. One possibility is the application of silver nanoparticles (AgNPs) that exhibit well-established antibacterial properties. Here, we synthesized AgNPs, stabilized by pectins (PEC) or sodium dodecyl sulphate (SDS), using a direct current atmospheric pressure glow discharge (dc-APGD) generated in an open-to-air and continuous-flow reaction-discharge system. Characterization of the PEC-AgNPs and SDS-AgNPs with UV/Vis absorption spectroscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction revealed the production of spherical, well dispersed, and face cubic centered crystalline AgNPs, with average sizes of 9.33 ± 3.37 nm and 28.3 ± 11.7 nm, respectively. Attenuated total reflection-Fourier transformation infrared spectroscopy supported the functionalization of the nanostructures by PEC and SDS. Antibacterial activity of the AgNPs was tested against Dickeya spp. and Pectobacterium spp. strains. Both PEC-AgNPs and SDS-AgNPs displayed bactericidal activity against all of the tested isolates, with minimum inhibitory concentrations of 5.5 mg∙L−1 and 0.75–3 mg∙L−1, respectively. The collected results suggest that the dc-APGD reaction-discharge system can be applied for the production of defined AgNPs with strong antibacterial properties, which may be further applied in plant disease management.

Highlights

Nanoparticles (NPs) exhibit unique thermal, chemical, optical, and mechanical [1] properties in comparison to the corresponding macroscopic scale forms
In the era of rapidly spreading antibiotic resistance among microorganisms, there is a high demand for efficient eradication methods effective against multiple bacterial species, and for which the emergence of resistant strains would be unlikely
Over 250 consumer products belonging to diverse sectors take advantage of the unique properties of AgNPs [29]; their more extensive usage within plant disease management is only a matter of time

Summary

Introduction

Nanoparticles (NPs) exhibit unique thermal, chemical, optical, and mechanical [1] properties in comparison to the corresponding macroscopic scale forms. Their noteworthy features are related to their high surface to volume ratio that increases as the average size of the NPs decrease. To meet the requirements of such diverse industries, numerous methods involving chemical (i.e., photo-, thermo-, sono-, and electrochemical), physical (i.e., laser ablation), and biological (i.e., green synthesis) procedures have been used in order to obtain stable-in-time AgNPs [2]. The biological synthesis procedures instead take advantage of plant extracts or essential oils as the reducing and stabilizing compounds, or involve soil microorganisms that are capable of synthesizing AgNPs from an appropriate precursor [1,3,4]

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