Pulse-Modulated Radio-Frequency Alternating-Current-Driven Atmospheric-Pressure Glow Discharge for Continuous-Flow Synthesis of Silver Nanoparticles and Evaluation of Their Cytotoxicity toward Human Melanoma Cells

Abstract

An innovative and environmentally friendly method for the synthesis of size-controlled silver nanoparticles (AgNPs) is presented. Pectin-stabilized AgNPs were synthesized in a plasma-reaction system in which pulse-modulated radio-frequency atmospheric-pressure glow discharge (pm-rf-APGD) was operated in contact with a flowing liquid electrode. The use of pm-rf-APGD allows for better control of the size of AgNPs and their stability and monodispersity. AgNPs synthesized under defined operating conditions exhibited average sizes of 41.62 ± 12.08 nm and 10.38 ± 4.56 nm, as determined by dynamic light scattering and transmission electron microscopy (TEM), respectively. Energy-dispersive X-ray spectroscopy (EDS) confirmed that the nanoparticles were composed of metallic Ag. Furthermore, the ξ-potential of the AgNPs was shown to be −43.11 ± 0.96 mV, which will facilitate their application in biological systems. Between 70% and 90% of the cancerous cells of the human melanoma Hs 294T cell line underwent necrosis following treatment with the synthesized AgNPs. Furthermore, optical emission spectrometry (OES) identified reactive species, such as NO, NH, N2, O, and H, as pm-rf-APGD produced compounds that may be involved in the reduction of the Ag(I) ions.

Production of antimicrobial silver nanoparticles modified by alkanethiol self‐assembled monolayers by direct current atmospheric pressure glow discharge generated in contact with a flowing liquid anode

“…Additionally, atomic lines of hydrogen (H α at 656.2 nm, H β at 486.1 nm) and oxygen (O I at 777.2; 777.4 and 844.6 nm) were identified. Similar reactive species were also found in the OES spectrum acquired for pm‐rf‐APGD incorporated for synthesis of Ag nanostructures stabilized by pectins . Reactive species identified in the above‐mentioned OES spectrum mostly resulted from excitation, dissociation, synthesis, and ionization processes of species coming from the liquid and surrounding air atmosphere.…”

“…A convenient solution to the abovementioned problems can be to apply a cold atmospheric pressure plasma (CAPP)‐based bottom‐up approach, based on generation of selected reactive oxygen and nitrogen species along with hydrated electrons and H radicals, which are involved in reducing AgNPs precursor ions . CAPP‐based methods have been utilized for environment‐friendly AgNP production by several research groups . In the above‐cited studies, different CAPPs are operated either in liquids or in contact with liquids, but in all cases stationary (nonflow‐through) reaction‐discharge systems are used.…”

“…Ag nanostructures’ production via the CAPP‐based bottom‐up approach has been typically carried out in the presence of capping agents, preventing their sedimentation and aggregation . Natural stabilizers such as gelatin, dextran, pectins, sucrose, fructose, or surfactants like sodium dodecyl sulfate, have been used to stabilize NPs synthesized in CAPP‐based systems. Alkanethiols are example of ligands that have been used to cap versatile noble metal nanostructures produced with the aid of non‐CAPP based synthesis procedures .…”

“…TMA allows to obtain stable nanoparticles, as well as noncytotoxic AgNPs with antimicrobial potential . Previously, dc‐APGD or pulse‐modulated radio‐frequency atmospheric pressure glow discharge (pm‐rf‐APGD), operated between the surface of flowing liquid electrodes and pin‐type W electrodes or a gaseous nozzle jet, was used in our group to synthesize Ag or Ag‐Au core‐shell nanostructures. Until now, operating conditions for production of size‐defined Ag nanostructures have only been optimized for the pm‐rf‐APGD reaction‐discharge system; no dc‐APGD reaction‐discharge system has been previously been optimized for that purpose.…”

Activation of the Normal Human Skin Cells by a Portable Dielectric Barrier Discharge-Based Reaction-Discharge System of a Defined Gas Temperature

“…Over the past few years, the interest of the controlled applications of CAPPs has rapidly increased. They include not only the utilization of CAPPs in dermatology [5][6][7][8][9][10][11][12][13][14][15][16][17][18], but also application of CAPP in the synthesis of nanomaterials [19][20][21], the germination of seeds [22], inhibiting the proliferation of cancers cell lines [23,24], and so on. This is possible because CAPP operation results in the generation of different reactive oxygen species (ROS, i.e., O 3 , H 2 O 2 , O•, O − 2 , OH•) and reactive nitrogen species (RNS, i.e., NO, NO 2 ), in addition to the emission of UV radiation and heat [7-9, 18, 25, 26].…”