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In this work, the effects of cold atmospheric‐pressure plasma (CAP) on glioblastoma are evaluated comprehensively. After CAP treatment, U251 cell viability, migration, and invasion functions were inhibited, while an appropriate dose of CAP had no inhibitory effect on human brain glial cell line cells. Western blots indicated that expression of caspase‐3 was upregulated with ki‐67 expression downregulated. Moreover, mitochondrial membrane potential decreased, and energy metabolisms of U251 cells were influenced afterward. TUNEL assays and comet assays suggested the DNA damage of U251 cells after CAP treatment. Furthermore, as one of the DNA damage responses associated pathways, the AKT (AKT8 virus oncogene cellular homolog) signaling pathway was also indicated in the work. The findings raise great promise for clinical applications of CAP in glioblastoma treatments. [ABSTRACT FROM AUTHOR]

Background: Tooth whitening with peroxide is linked to a number of negative consequences. This study aimed to evaluate the effect of tooth bleaching and color safety using no-ozone cold atmospheric-pressure plasma (NCP) with distilled water (DW) and to assess the microhardness and mineral composition of the treated teeth. Methods: The enamel of 90 extracted human teeth were randomly assigned to three groups (n = 30): Group 1 (no treatment), Group 2 (NCP + DW), and Group 3 (only DW). The overall color change (ΔE) was observed at 10 min, 20 min, 30 min, 1 day, 7 days, 1 month, 3 months, and 6 months after treatment and quantified. Six cadavers treated with NCP and DW for 30 min were evaluated for color change using ShadeEye NCC and the VITA Easyshade. Furthermore, the microhardness and mineral composition of the teeth were evaluated using a Vickers hardness tester and an electro micro analyzer, respectively. All statistical data were analyzed at a significance level of 5%. Results: Group 1 showed no color change. The ΔE values of Group 2 were 17.67 and 5.62 times higher than those of Group 3 after 30 min and 6 months, respectively. Methylene blue solution revealed that the concentration of hydroxyl radicals was higher in Group 2. The average ΔE value using ShadeEye NCC for cadaveric teeth was 4.0. Evaluation via VITA Easyshade showed that the brightness was increased by 5 levels. No significant differences were observed among the groups in terms of the microhardness of the enamel and dentin or the Ca, P, Na, Cl, Zn, and Mg values in the enamel and dentin. Conclusions: Tooth bleaching using NCP with DW exhibited high efficacy without inducing damage or demineralization in the dental hard tissue.

Despite notable advances in anticancer drug development, their manufacture and use pose environmental and health risks due to toxic byproducts, drug residue contamination, and cytotoxicity to normal cells. Therefore, developing cost-effective anticancer treatments with fewer toxic side effects and higher selectivity is essential to the advancement of highly effective anticancer therapies. Plasma-activated water (PAW) offers a green alternative to conventional chemical treatments as it reverts to water within days. However, the limited duration and dose of reactive oxygen and nitrogen species (RONS) in acidified PAW restrict its clinical deployment and the full understanding of their mechanism. In this study, we propose alkaline PAW as an innovative enhancement of the RONS technology. The alkaline PAW generated markedly superior RONS, with about 10 times higher levels of NO 2 - , H 2 O 2 , and ONOO - /O 2 •- than acidic PAW. The possible RONS generation pathways in alkaline PAW are analyzed by scavengers. In conventional acidic PAW, 70% of the H 2 O 2 concentration is contributed by • OH but only about 20% in alkaline PAW. ONOO - is mainly formed through the reaction of O 2 •- with NO in alkaline pH, while in acidic PAW, it mainly forms from NO 2 - and H 2 O 2 . The results unveiled the synergistic and formidable anticancer effects of alkaline PAW against cancer cells, typified by an increase in intracellular ROS/RNS levels. Furthermore, alkaline PAW injection also effectively prevented xenograft tumor growth in mice. We systematically investigated this high-dose anticancer solution without using noble gases, toxic reagents, or extra energy consumption and successfully demonstrated the possibility of alkaline PAW being an effective and environmentally friendly therapeutic technology. The activity is closely linked to the RONS dose, and the generation pathway provides much-needed insight into the fundamental aspects of PAW chemistry required for the optimization of the biochemical activity of PAW.

Non-thermal atmospheric-pressure plasma has emerged as a useful tool in life science research and medicine. Plasma irradiation generates reactive oxygen and nitrogen species (RONS) that stimulate various cellular responses. In this study, we investigated oxidative damage to nuclear and mitochondrial DNA in A549 human lung cancer cells exposed to a helium atmospheric-pressure plasma jet (APPJ). APPJ irradiation decreased the viability of A549 cells and increased intracellular RONS levels. The formation of 8-oxoguanine (8-oxoG), a representative oxidized form of a DNA base, was observed in nuclear DNA. Pretreatment of A549 cells with an antioxidant reagent prior to APPJ irradiation suppressed the increase in 8-oxoG level. The 8-oxoG level gradually decreased during cell culture, suggesting that 8-oxoG was removed from nuclear DNA after APPJ irradiation. Formation of 8-oxoG was also observed in mitochondrial DNA, indicating the accumulation of RONS in mitochondria. [ABSTRACT FROM AUTHOR]

The arbitrary electron energy distribution function (EEDF) of cold atmospheric-pressure plasma is determined from optical emission spectroscopy measurement. Using the electron-neutral bremsstrahlung-dominated continuum spectrum and relevant cross-section data, a partial arbitrary EEDF can be reconstructed through the reinforcement learning-based visible bremsstrahlung inversion method. From an atmospheric-pressure argon dielectric barrier discharge plasma emission spectrum (440â€"900 nm), a partial arbitrary EEDF can be determined with a resolution of 0.2 eV. The resemblance between the obtained arbitrary EEDF and a two-temperature Maxwellian was found with T e  = 0.26 and 2.2 eV. The EEDF range is mostly constrained by the spectrum wavelength range. [ABSTRACT FROM AUTHOR]

Aims: This study aimed to compare the efficacy of plasma‐activated water (PAW) generated by two novel plasma reactors against pathogenic foodborne illness organisms. Methods and results: The antimicrobial efficacy of PAW produced by a bubble spark discharge (BSD) reactor and a dielectric barrier discharge‐diffuser (DBDD) reactor operating at atmospheric conditions with air, multiple discharge frequencies and Milli‐Q and tap water, was investigated with model organisms Listeria innocua and Escherichia coli in situ. Optimal conditions were subsequently employed for pathogenic bacteria Listeria monocytogenes, E. coli and Salmonella enterica. DBDD‐PAW reduced more than 6‐log of bacteria within 1 min. The BSD‐PAW, while attaining high log reduction, was less effective. Analysis of physicochemical properties revealed that BSD‐PAW had a greater variety of reactive species than DBDD‐PAW. Scavenger assays designed to specifically sequester reactive species demonstrated a critical role of superoxide, particularly in DBDD‐PAW. Conclusions: DBDD‐PAW demonstrated rapid antimicrobial activity against pathogenic bacteria, with superoxide the critical reactive species. Significance and impact of study: This study demonstrates the potential of DBDD‐PAW produced using tap water and air as a feasible and cost‐effective option for antimicrobial applications, including food safety. [ABSTRACT FROM AUTHOR]

Systemic infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are life-threatening due to their strong multidrug resistance, especially since the biofilms formed by MRSA are more difficult to inactivate by antibiotics, causing long term recurrence of infection. Plasma-activated saline (PAS), a derived form of cold atmospheric-pressure plasma, can effectively inactivate bacteria and cancer cells and has been applied to sterilization and cancer treatment. Previous studies have demonstrated that the pretreatment of MRSA with PAS could promote the action of antibiotics. Here, the PAS was used as an antibiotic adjuvant to promote the inactivation of MRSA biofilms by rifampicin and vancomycin, and the combined treatment reduced approximately 6.0-log10 MRSA cells in biofilms. The plasma-activated saline and rifampicin synergistically and effectively reduced the systemic infection in the murine model. The histochemical analysis and the blood hematological and biochemical test demonstrated that the combined treatment with plasma-activated saline and rifampicin improved the blood hematological and biochemical parameters of infected mice by reducing the infection. Therefore, PAS based on plasma technology represents a new strategy for the treatment of infectious disease caused by multidrug-resistant bacteria and alleviating antibiotic resistance.

Biofilms formed by multidrug-resistant bacteria are a major cause of hospital-acquired infections. Cold atmospheric-pressure plasma (CAP) is attractive for sterilization, especially to disrupt biofilms formed by multidrug-resistant bacteria. However, the underlying molecular mechanism is not clear. In this study, CAP effectively reduced the living cells in the biofilms formed by methicillin-resistant Staphylococcus aureus, and 6 min treatment with CAP reduced the S. aureus cells in biofilms by 3.5 log10. The treatment with CAP caused the polymerization of SaFtsZ and SaClpP proteins in the S. aureus cells of the biofilms. In vitro analysis demonstrated that recombinant SaFtsZ lost its self-assembly capability, and recombinant SaClpP lost its peptidase activity after 2 min of treatment with CAP. Mass spectrometry showed oxidative modifications of a cluster of peaks differing by 16 Da, 31 Da, 32 Da, 47 Da, 48 Da, 62 Da, and 78 Da, induced by reactive species of CAP. It is speculated that the oxidative damage to proteins in S. aureus cells was induced by CAP, which contributed to the reduction of biofilms. This study elucidates the biological effect of CAP on the proteins in bacterial cells of biofilms and provides a basis for the application of CAP in the disinfection of biofilms.

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of serious nosocomial infections, and recurrent MRSA infections primarily result from the survival of persister cells after antibiotic treatment. Gas plasma, a novel source of ROS (reactive oxygen species) and RNS (reactive nitrogen species) generation, not only inactivates pathogenic microbes but also restore the sensitivity of MRSA to antibiotics. This study further found that sublethal treatment of MRSA with both plasma and plasma-activated saline increased the antibiotic sensitivity and promoted the eradication of persister cells by tetracycline, gentamycin, clindamycin, chloramphenicol, ciprofloxacin, rifampicin, and vancomycin. The short-lived ROS and RNS generated by plasma played a primary role in the process and induced the increase of many species of ROS and RNS in MRSA cells. Thus, our data indicated that the plasma treatment could promote the effects of many different classes of antibiotics and act as an antibiotic sensitizer for the treatment of antibiotic-resistant bacteria involved in infectious diseases.

Cold atmospheric-pressure plasma (CAP) has been emerging as a promising tool for cancer therapy in recent times. In this study, we used a CAP device with nitrogen gas (N 2 CAP) and investigated the effect of the N 2 CAP on the viability of cultured cells. Moreover, we investigated whether N 2 CAP-produced hydrogen peroxide (H 2 O 2 ) in the medium is involved in N 2 CAP-induced cell death. Here, we found that the N 2 CAP irradiation inhibited cell proliferation in the human embryonic kidney cell line HEK293T and that the N 2 CAP induced cell death in an irradiation time- and distance-dependent manner. Furthermore, the N 2 CAP and H 2 O 2 increased intracellular calcium levels and induced caspase-3/7 activation in HEK293T cells. The N 2 CAP irradiation induced a time-dependent production of H 2 O 2 and nitrite/nitrate in PBS or culture medium. However, the amount of H 2 O 2 in the solution after N 2 CAP irradiation was too low to induce cell death. Interestingly, carboxy-PTIO, a nitric oxide scavenger, or BAPTA-AM, a cell-permeable calcium chelator, inhibited N 2 CAP-induced morphological change and cell death. These results suggest that the production of reactive nitrogen species and the increase in intracellular calcium were involved in the N 2 CAP-induced cell death. [ABSTRACT FROM AUTHOR]

Viruses are serious pathogenic contamination that severely affect the environment and human health. Cold atmospheric-pressure plasma efficiently inactivates pathogenic bacteria, however, the mechanism of virus inactivation by plasma is not fully understood. In this study, surface plasma in argon mixed with 1% air and plasma-activated water were used to treat water containing bacteriophages. Both agents efficiently inactivated bacteriophages T4, Φ174, and MS2 in a time-dependent manner. Prolonged storage had marginal effects on the anti-viral activity of plasma-activated water. DNA and protein analysis revealed that the reactive species generated by plasma damaged both nucleic acid and proteins, in consistent with the morphological examination showing that plasma treatment caused the aggregation of bacteriophages. The inactivation of bacteriophages was alleviated by the singlet oxygen scavengers, demonstrating that singlet oxygen played a primary role in this process. Our findings provide a potentially effective disinfecting strategy to combat the environmental viruses using cold atmospheric-pressure plasma and plasma-activated water. [ABSTRACT FROM AUTHOR]

Reactive oxygen and nitrogen species (ROS and RNS) generated by cold atmospheric-pressure plasma could damage genomic DNA, although the precise types of these DNA damage induced by plasma are poorly characterized. Understanding plasma-induced DNA damage will help to elucidate the biological effect of plasma and guide the application of plasma in ROS-based therapy. In this study, it was shown that ROS and RNS generated by physical plasma could efficiently induce DNA-protein crosslinks (DPCs) in bacteria, yeast, and human cells. An in vitro assay showed that plasma treatment resulted in the formation of covalent DPCs by activating proteins to crosslink with DNA. Mass spectrometry and hydroperoxide analysis detected oxidation products induced by plasma. DPC formation were alleviated by singlet oxygen scavenger, demonstrating the importance of singlet oxygen in this process. These results suggested the roles of DPC formation in DNA damage induced by plasma, which could improve the understanding of the biological effect of plasma and help to develop a new strategy in plasma-based therapy including infection and cancer therapy. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of serious nosocomial infections, and recurrent MRSA infections primarily result from the survival of persister cells after antibiotic treatment. Gas plasma, a novel source of ROS (reactive oxygen species) and RNS (reactive nitrogen species) generation, not only inactivates pathogenic microbes but also restore the sensitivity of MRSA to antibiotics. This study further found that sublethal treatment of MRSA with both plasma and plasma-activated saline increased the antibiotic sensitivity and promoted the eradication of persister cells by tetracycline, gentamycin, clindamycin, chloramphenicol, ciprofloxacin, rifampicin, and vancomycin. The short-lived ROS and RNS generated by plasma played a primary role in the process and induced the increase of many species of ROS and RNS in MRSA cells. Thus, our data indicated that the plasma treatment could promote the effects of many different classes of antibiotics and act as an antibiotic sensitizer for the treatment of antibiotic-resistant bacteria involved in infectious diseases. [ABSTRACT FROM AUTHOR]

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.

Plasma is ionized gas, which is found in various forms in nature and can also be generated artificially. A variety of cold atmospheric-pressure plasmas are currently being investigated for their clinical utility, and first studies reporting on the treatment of patients showed that plasma treatment may support the wound healing process. One of the benefits of plasma treatment is the effective inactivation of bacteria including tenacious pathogens such as Pseudomonas aeruginosa or multiresistant Staphylococcus aureus (MRSA). Neither the molecular mechanisms promoting wound healing nor those underlying bacterial inactivation are fully understood yet. The review has a focus on plasma jets, a particular type of cold atmospheric-pressure plasma sources featuring an indirect treatment whereby the treated substrates do not come into contact with the plasma directly but are exposed to the plasma-emitted reactive species and photons. Such plasma jets are being employed as tools in basic research regarding the effects of plasmas on biological samples. This review provides a brief overview on the recent clinical investigations into the benefits of cold atmospheric-pressure plasmas. It then describes our current understanding of the mechanisms leading to bacterial inactivation and inactivation of biomacromolecules gained by employing plasma jets. [ABSTRACT FROM AUTHOR]

The main focus of current research was on the effect of cold atmospheric-pressure plasma (CAP) on the rheological properties of gum Arabic (GA). GA powder was treated by dielectric barrier discharge (DBD) plasma with ambient air at different times (20, 40, and 60 min). The rheological properties of both natural and treated-gum dispersions were specified. The results showed the CAP treatment time had a notable and non-linear effect on the rheological parameters of the treated gums. Compared with control, all treated-gum dispersions showed higher apparent viscosity within the applied shear rate range (0.01–400 s−1). The highest viscosity (50 s−1) belonged to the dispersion of the gum treated for 20 min. CAP treatment significantly (p < 0.05) increased the shear-thinning behavior of the treated-gum dispersions. Power-law was the best model for describing the flow behavior of natural GA and treated-gum dispersions. The obtained dynamic rheological parameters (G′ and tan δ) revealed that CAP treatment reinforced the elastic properties of treated-gum dispersions, and the shortest treatment time, 20 min, was more effective in this case. Overall, it was found that the CAP-treated gums by strengthening the elastic features of dispersions could be obtained for new applications in the production of foodstuffs especially beverages. [Display omitted] • Plasma improved the viscosity and elastic-like behavior of gum Arabic. • Flow behavior of both natural and treated-gums well defined by Power-law. • Cold plasma treatment was not able to change the liquid-like behavior of GA. • Treatment time had a significant effect on the rheological properties. • Shortest treatment time was more effective in structural strength of dispersion. [ABSTRACT FROM AUTHOR]

Systemic infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are life-threatening due to their strong multidrug resistance, especially since the biofilms formed by MRSA are more difficult to inactivate by antibiotics, causing long term recurrence of infection. Plasma-activated saline (PAS), a derived form of cold atmospheric-pressure plasma, can effectively inactivate bacteria and cancer cells and has been applied to sterilization and cancer treatment. Previous studies have demonstrated that the pretreatment of MRSA with PAS could promote the action of antibiotics. Here, the PAS was used as an antibiotic adjuvant to promote the inactivation of MRSA biofilms by rifampicin and vancomycin, and the combined treatment reduced approximately 6.0-log10 MRSA cells in biofilms. The plasma-activated saline and rifampicin synergistically and effectively reduced the systemic infection in the murine model. The histochemical analysis and the blood hematological and biochemical test demonstrated that the combined treatment with plasma-activated saline and rifampicin improved the blood hematological and biochemical parameters of infected mice by reducing the infection. Therefore, PAS based on plasma technology represents a new strategy for the treatment of infectious disease caused by multidrug-resistant bacteria and alleviating antibiotic resistance. [ABSTRACT FROM AUTHOR]

Biofilms formed by multidrug-resistant bacteria are a major cause of hospital-acquired infections. Cold atmospheric-pressure plasma (CAP) is attractive for sterilization, especially to disrupt biofilms formed by multidrug-resistant bacteria. However, the underlying molecular mechanism is not clear. In this study, CAP effectively reduced the living cells in the biofilms formed by methicillin-resistant Staphylococcus aureus, and 6 min treatment with CAP reduced the S. aureus cells in biofilms by 3.5 log10. The treatment with CAP caused the polymerization of SaFtsZ and SaClpP proteins in the S. aureus cells of the biofilms. In vitro analysis demonstrated that recombinant SaFtsZ lost its self-assembly capability, and recombinant SaClpP lost its peptidase activity after 2 min of treatment with CAP. Mass spectrometry showed oxidative modifications of a cluster of peaks differing by 16 Da, 31 Da, 32 Da, 47 Da, 48 Da, 62 Da, and 78 Da, induced by reactive species of CAP. It is speculated that the oxidative damage to proteins in S. aureus cells was induced by CAP, which contributed to the reduction of biofilms. This study elucidates the biological effect of CAP on the proteins in bacterial cells of biofilms and provides a basis for the application of CAP in the disinfection of biofilms. [ABSTRACT FROM AUTHOR]

Simple Summary: One fundamental feature that has emerged from in vitro application of cold plasmas in cancer treatment is the key role of the liquid phase covering the cells. In the present work, we investigated the effect of direct and indirect plasma treatments on two cancer and three normal cell lines to assess the benefits of one treatment over the other in terms of death of tumor versus healthy cells. Our results demonstrate that indirect plasma treatment is as efficient at killing tumor cells as an appropriate combination of H2O2, NO2− and acidic pH in ad hoc solutions, while sparing normal cells. However, direct plasma treatment is far more efficient at killing normal than tumor cells, and we provide evidence that short- and long-lived reactive species contribute synergistically to kill normal cells, while having an additive effect regarding tumor cell death. Collectively, our results call the use of plasma-activated liquid in cancer treatment into question. (1) Plasma-activated liquids (PAL) have been extensively studied for their anti-cancer properties. Two treatment modalities can be applied to the cells, direct and indirect plasma treatments, which differ by the environment to which the cells are exposed. For direct plasma treatment, the cells covered by a liquid are present during the plasma treatment time (phase I, plasma ON) and the incubation time (phase II, plasma OFF), while for indirect plasma treatment, phase I is cell-free and cells are only exposed to PAL during phase II. The scope of this work was to study these two treatment modalities to bring new insights into the potential use of PAL for cancer treatment. (2) We used two models of head and neck cancer cells, CAL27 and FaDu, and three models of normal cells (1Br3, NHK, and RPE-hTERT). PBS was used as the liquid of interest, and the concentration of plasma-induced H2O2, NO2− and NO3−, as well as pH change, were measured. Cells were exposed to direct plasma treatment, indirect plasma treatment or reconstituted buffer (PBS adjusted with plasma-induced concentrations of H2O2, NO2−, NO3− and pH). Metabolic cell activity, cell viability, lipid peroxidation, intracellular ROS production and caspase 3/7 induction were quantified. (3) If we showed that direct plasma treatment is slightly more efficient than indirect plasma treatment and reconstituted buffer at inducing lipid peroxidation, intracellular increase of ROS and cancer cell death in tumor cells, our data also revealed that reconstituted buffer is equivalent to indirect plasma treatment. In contrast, normal cells are quite insensitive to these two last treatment modalities. However, they are extremely sensitive to direct plasma treatment. Indeed, we found that phase I and phase II act in synergy to trigger cell death in normal cells and are additive concerning tumor cell death. Our data also highlight the presence in plasma-treated PBS of yet unidentified short-lived reactive species that contribute to cell death. (4) In this study, we provide strong evidence that, in vitro, the concentration of RONS (H2O2, NO2− and NO3−) in combination with the acidic pH are the main drivers of plasma-induced PBS toxicity in tumor cells but not in normal cells, which makes ad hoc reconstituted solutions powerful anti-tumor treatments. In marked contrast, direct plasma treatment is deleterious for normal cells in vitro and should be avoided. Based on our results, we discuss the limitations to the use of PAL for cancer treatments. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the effect of cold atmospheric-pressure plasma (CAP) on the structural aspects and some physicochemical properties of gum arabic (GA), with emphasis on its surface properties. GA was treated at dielectric barrier discharge (DBD) plasma with ambient air for different times (20, 40, and 60 min). The optical emission spectroscopy (OES) was utilized to scope present active species in the plasma. Upon treatment, the structural, thermal and morphological variations, as well as changes in water contact angle, surface and interfacial tension, molecular weight, solubility, moisture content and color of the treated gums, were studied. Compared with GA, overall significant changes in the spectra of all treated gums were recognized, particularly in the range of 1200–1750 cm−1. Elemental analysis of surface demonstrated that both oxygen and nitrogen content of treated gum increased time-dependently. Plasma had no pronounced effect on the amorphous nature of GA. Water contact angle data showed that plasma treatment was surprisingly capable of transforming GA hydrophilic nature into hydrophobic. The surface roughness of the treated gums powder time-dependently increased. The molecular weight, solubility, and moisture content of treated gum nonlinearly decreased with increasing treatment duration. The surface and interfacial tension significantly decreased after CAP treatment. The thermal properties and color of the treated gums changed after CAP treatment. In total, this study confirmed that the CAP treatment was an efficient approach to improve surface properties of gum arabic. Image 1 • Plasma treatment improved surface properties of gum arabic. • DBD-air plasma treatment turned hydrophilic gum into hydrophobic. • Interfacial tension of all treated gums linearly decreased with increasing treatment time. • A sharp reduction in surface tension was observed at the lowest plasma treatment duration. • FT-IR, DSC, contact angle, surface tension, and interfacial tension results confirmed plasma treatment changed the proportion of polar-apolar groups in gum structure. [ABSTRACT FROM AUTHOR]

We report experiments in which reactive oxygen species (ROS) from a 20 kHz HV discharge in Ar/O2 (90/10) gas mixture at atmospheric pressure were directly bubbled into highly concentrated aqueous suspensions of cyanobacteria Dolichospermum, green algae Scenedesmus and BMAA toxin, simulating extreme algal blooms. It has been found that even quite short treatment durations, up to 6 min, could greatly reduce the numbers of viable cells and completely destroy the BMAA toxin. Perhaps even more important, "plasma‐activated water" (PAW) was found to continue its effectiveness after 24 h, even 4 days after terminating the discharge. We report the outstanding effects of "plasma‐activated water" (PAW), obtained with Ar/O2 (90/10) atmospheric pressure discharges generated at water/bubbles interfaces, on suspensions of cyanobacteria Dolichospermum, green algae Scenedesmus and BMAA toxin, simulating extreme algal blooms. Quite short treatment durations (up to 6 min) could greatly reduce the numbers of viable cells and completely destroy the BMAA toxin. Perhaps even more important, PAW was found to continue its effectiveness even 4 days after terminating the discharge. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Viruses cause serious pathogenic contamination that severely affects the environment and human health. Cold atmospheric-pressure plasma efficiently inactivates pathogenic bacteria; however, the mechanism of virus inactivation by plasma is not fully understood. In this study, surface plasma in argon mixed with 1% air and plasma-activated water was used to treat water containing bacteriophages. Both agents efficiently inactivated bacteriophages T4, Φ174, and MS2 in a time-dependent manner. Prolonged storage had marginal effects on the antiviral activity of plasma-activated water. DNA and protein analysis revealed that the reactive species generated by plasma damaged both nucleic acids and proteins, consistent with the morphological examination showing that plasma treatment caused the aggregation of bacteriophages. The inactivation of bacteriophages was alleviated by the singlet oxygen scavengers, demonstrating that singlet oxygen played a primary role in this process. Our findings provide a potentially effective disinfecting strategy to combat the environmental viruses using cold atmospheric-pressure plasma and plasma-activated water. IMPORTANCE Contamination with pathogenic and infectious viruses severely threatens human health and animal husbandry. Current methods for disinfection have different disadvantages, such as inconvenience and contamination of disinfection by-products (e.g., chlorine disinfection). In this study, atmospheric surface plasma in argon mixed with air and plasma-activated water was found to efficiently inactivate bacteriophages, and plasma-activated water still had strong antiviral activity after prolonged storage. Furthermore, it was shown that bacteriophage inactivation was associated with damage to nucleic acids and proteins by singlet oxygen. An understanding of the biological effects of plasma-based treatment is useful to inform the development of plasma into a novel disinfecting strategy with convenience and no by-product., (Copyright © 2018 Guo et al.)