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Allergic contact dermatitis (ACD) is a common inflammatory skin disease that accounts for approximately 20% of all occupational skin diseases. As an adverse and recurrent inflammatory dermatological agent, ACD shows insufficient response to current therapies largely owing to abnormal inflammatory activation and accompanying bacterial infection in lesions. Cold atmospheric plasma is a noninvasive fledgling reactive oxygen and nitrogen species (RONS)-based therapeutic technique for ACD treatment; however, its clinical adoption has been hindered due to the risk of electrical burns and insufficient delivery of the plasma-generated RONS. To address these limitations, we constructed plasma-activated AVC (PA-AVC) hydrogels loaded with plasma-generated RONS for ACD treatment as an alternative to the common direct plasma irradiation treatment. The proposed PA-AVC hydrogels were produced on a biodegradable acryloyldimethylammonium taurate/VP copolymer (AVC) with the aid of a novel air discharge plasma without the involvement of any catalyst. In vitro data showed that abundant RONS were produced and incorporated into the PA-AVC hydrogels via complex gas-liquid reactions between the air discharge plasma and hydrosolvent; additionally, the PA-AVC hydrogels exhibited excellent storage, slow release and transdermal delivery of RONS as well as good antibacterial effects. Moreover, in vivo experiments demonstrated that PA-AVC hydrogels effectively alleviated the ACD symptoms, such as skin redness and swelling, reduced epidermal thickening and inhibited mast cell infiltration and IL-9, TNF-α, and TSLP expression with no evident systemic toxicity. Our results revealed that long-acting plasma-activated AVC hydrogels could be effective therapeutic agents for local ACD treatment.

Cold atmospheric plasma (CAP) is a fledgling therapeutic technique for psoriasis treatment with noninvasiveness, but clinical adoption has been stifled by the insufficient production and delivery of plasma-generated reactive oxygen and nitrogen species (RONS). Herein, patches of air-discharge plasma-activated ice microneedles (PA-IMNs) loaded with multiple RONS are designed for local transdermal delivery to treat psoriasis as an alternative to direct CAP irradiation treatment. By mixing two RONS generated by the air-discharge plasma in the NO x mode and O 3 mode, abundant high-valence RONS are produced and incorporated into PA-IMNs via complex gas-gas and gas-liquid reactions. The PA-IMNs abrogate keratinocyte overproliferation by inducing reactive oxygen species (ROS)-mediated loss of the mitochondrial membrane potential and apoptosis of keratinocytes. The in vivo transdermal treatment confirms that PA-IMNs produce significant anti-inflammatory and therapeutic actions for imiquimod (IMQ)-induced psoriasis-like dermatitis in mice by inhibiting the release of associated inflammatory factors while showing no evident systemic toxicity. Therefore, PA-IMNs have a large potential in transdermal delivery platforms as they overcome the limitations of using CAP directly in the clinical treatment of psoriasis.

The disinfection of fabrics is crucial in preventing the spread of infectious diseases caused by pathogenic microorganisms to maintain public health. A previous study proved that plasma-activated nebulized mist (PANM) could effectively inactivate microorganisms both in aerosol and attached to the surface. In this study, the PANM driven by different plasma gases were employed to inactivate microorganisms on diverse fabrics. The PANM could efficiently inactivate a variety of microorganisms, including bacteria, fungi, and viruses, contaminating different fabrics, and even across covering layers of different fabrics. The mites residing on the cotton fabrics both uncovered and covered with various types of fabrics were also effectively inactivated by the PANM. After 30 times repeated treatments of the PANM, notable changes were observed in the color of several fabrics while the structural integrity and mechanical strength of the fabrics were unaffected and maintained similarly to the untreated fabrics with slight changes in elemental composition. Additionally, only trace amounts of nitrate remained in the fabrics after the PANM treatment. Therefore, the PANM treatment supplied an efficient, broad-spectrum, and environmentally friendly strategy for industrial and household disinfection of fabrics., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The release of toxic fluoride byproducts is a seemingly unavoidable artifact of surface engineering, causing severe environmental and human health problems. Here we propose and implement a new "upcycle hazard against other hazard" concept in the case study of cold atmospheric plasma surface modification of fluoropolymers such as polytetrafluorethylene (PTFE). Capitalizing on the excellent controllability, precision and energy efficiency of the plasma surface processing, complemented with the recently discovered ability of plasmas to activate water to produce a potent electrochemical disinfectant, referred to as the plasma-activated water (PAW), we demonstrate a radically new solution to capture the hazardous gaseous fluorides into the PAW and use the as-fluorinated PAW (F-PAW) as a very effective antimicrobial disinfectant. A customized surface discharge reactor is developed to evaluate the effects of fluorides released from the plasma etching of PTFE on the chemistries in gas-phase plasmas and F-PAW, as well as the antibacterial effect of F-PAW. The results show that gaseous fluorides, including COF 2 , CF 3 COF, and SiF 4 are produced in gas-phase plasmas, and the dissolution of thus-generated fluorides into PAW has a strong effect on inactivating catalase and destroying the oxidation resistance of bacterial cells. As a result, the antibacterial effect of PAW-fluorides against the methicillin-resistant Staphylococcus aureus (MRSA) is enhanced by > 5 log reductions, suggesting that otherwise hazardous fluorides from the plasma processing of PTFE can be used to enhance the microbial disinfection efficiency of PAW. The demonstrated approach opens new avenues for sustainable hazard valorization exemplified by converting toxic fluoride-etching products into potent antimicrobial and potentially anti-viral disinfectants., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Cold atmospheric plasma (CAP) represents a promising therapy for selectively cancer killing. However, the mechanism of CAP-induced cancer cell death remains unclear. Here, we identified the tumor necrosis factor-family members, especially Fas, and overloaded intracellular nitric oxide participated in CAP induced apoptosis in A375 and A875 melanoma cell lines, which was known as extrinsic apoptosis pathway. This progress was mediated by antagonistic protein of reactive oxygen species, Sestrin2. The over expression of Sestrin2 induced by plasma treatment resulted in phosphorylation of p38 mitogen-activated protein kinase (MAPK), followed by increased expression of nitric oxide synthase (iNOS), Fas and Fas ligand. Depletion of Sestrin2 reduced iNOS and Fas expression, which was associated with reduction of plasma-induced apoptosis. In contrast, inhibition of iNOS activity and phosphorylation of p38 did not alter Sestrin2 expression in plasma-treated melanoma cells. Taken together, cold atmospheric plasma increases Sestrin2 expression and further activates downstream iNOS, Fas and p38 MAPK signaling to induce apoptosis of melanoma cell lines. These findings suggest a previously unrecognized mechanism in melanoma cells response to cold atmospheric plasma therapy., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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.)

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.

Cold atmospheric plasma was shown to induce cell apoptosis in numerous tumor cells. Recently, some other biological effects, such as induction of membrane permeation and suppression of migration, were discovered by plasma treatment in some types of tumor cells. In this study, we investigated the biological effects of plasma treatment on multiple myeloma cells. We detected the detachment of adherent myeloma cells by plasma, and the detachment area was correlated with higher density of hydroxyl radical in the gas phase of the plasma. Meanwhile, plasma could promote myeloma differentiation by up-regulating Blimp-1 and XBP-1 expression. The migration ability was suppressed by plasma treatment through decreasing of MMP-2 and MMP-9 secretion. In addition, plasma could increase bortezomib sensitivity and induce myeloma cell apoptosis. Taking together, combination with plasma treatment may enhance current chemotherapy and probably improve the outcomes., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Plasma is highly efficient in the inactivation of microorganisms and is tried to be applied to the treatment of wounds. The gas activated by plasma, named plasma-activated gas, can also effectively inactivate microorganisms and get rid of the limitations of direct plasma treatment. However, the details of the interaction of plasma-activated gas on the tissue are still unclear. In this study, the agarose gel models in the presence of microorganisms to simulate the infected tissues were used to study the inactivation effects and mechanisms of plasma-activated gas. The inactivation depths in the gel models in the presence of microorganisms were related to the types of plasma-activated gas and the species of microorganisms. The Mixed-gas exhibited the strongest inactivation effects, and the inactivation depths in the gel models in the presence of bacteria were deeper than those in the presence of fungi. The long-lived species in the plasma-activated gas penetrated to more than 5.2 mm while the short-lived species only penetrated less than 2.3 mm, demonstrating the distinct roles of reactive species in the inactivation process. Moreover, the pig muscle was covered on the gel models to assess the penetration depths of the plasma-activated gas in muscle tissue and the focused plasma-activated gas could penetrate 1–1.5 mm of pig muscle. This study explored the inactivation effects and mechanisms on the gel models and the penetration depths in the real tissues of plasma-activated gas, which supplied the theoretical basis for the further application of plasma-activated gas in biomedical fields. [ABSTRACT FROM AUTHOR]

Gliding arc is a promising plasma technology for water activation due to its high energy efficiency for producing reactive nitrogen species (RNS), which is believed as the key agent for the sustained bactericidal effect of plasma-activated water (PAW). Nitric oxide (NO) is the major product of gliding arc and also widely exists in PAW, but the production mechanism of aqueous NO and its role in sterilization have been little investigated before. In this paper, NO-rich plasma effluent gas is produced by gliding arc discharge and introduced into water to produce PAW. The concentrations of gaseous and aqueous reactive species are detected, which decrease with the increasing air flowrate of the gliding arc. To clarify the contribution of plasma-induced RNS on water activation, the NO + air mixed gas is used to simulate the plasma effluent gas, and the results show that the two gases have similar gaseous composition and aqueous NO yield. Compared with the NO + Ar mixed gas with the same NO proportion, the NO + air mixed gas produces much more aqueous NO, implying that the presence of O2 significantly enhances the production of aqueous NO. The sterilization experiments demonstrate the key role of aqueous NO in sterilization, but an acidic environment is necessary for aqueous NO to achieve a potent bactericidal effect. [ABSTRACT FROM AUTHOR]

Gliding arc is a promising plasma technology for water activation due to its high energy efficiency for producing reactive nitrogen species (RNS), which is believed as the key agent for the sustained bactericidal effect of plasma-activated water (PAW). Nitric oxide (NO) is the major product of gliding arc and also widely exists in PAW, but the production mechanism of aqueous NO and its role in sterilization have been little investigated before. In this paper, NO-rich plasma effluent gas is produced by gliding arc discharge and introduced into water to produce PAW. The concentrations of gaseous and aqueous reactive species are detected, which decrease with the increasing air flowrate of the gliding arc. To clarify the contribution of plasma-induced RNS on water activation, the NO + air mixed gas is used to simulate the plasma effluent gas, and the results show that the two gases have similar gaseous composition and aqueous NO yield. Compared with the NO + Ar mixed gas with the same NO proportion, the NO + air mixed gas produces much more aqueous NO, implying that the presence of O2 significantly enhances the production of aqueous NO. The sterilization experiments demonstrate the key role of aqueous NO in sterilization, but an acidic environment is necessary for aqueous NO to achieve a potent bactericidal effect. [ABSTRACT FROM AUTHOR]

An argon plasma jet with gas admixtures of 0.2% ethanol (EtOH) and 0.08% oxygen, which has promising prospects in sterilization and anti-infection, is studied. EtOH can convert an argon plasma jet from filamentary mode into diffuse mode, as reported previously, and O2 can further enhance its bactericidal effect dramatically. Compared to the Ar+EtOH plasma jet, the Ar+EtOH+O2 plasma jet is still in diffuse mode, but its bactericidal effect increases by more than five orders of magnitude when used to treat Methicillin-resistant Staphylococcus aureus (MRSA) suspensions (∼1 × 108 CFU ml−1). Such a strong bactericidal effect can also be achieved by using deionized water activated by an Ar+EtOH+O2 plasma jet, even when the plasma-activated water has been stored for 3 min before mixing with the MRSA suspension. This implies that some new antibacterial species are produced by the Ar+EtOH+O2 plasma jet compared to the Ar+EtOH plasma jet, which plays a crucial role in sterilization. Compared to the Ar+EtOH plasma jet, the Ar+EtOH+O2 plasma jet decomposes more EtOH molecules, and some new gaseous species, such as CO2, CH3COOOH, CH3COCH2+, COOO−, HCOOO− and CH3COOO−, are produced. CH3COOOH also exists in plasma-activated water with a lifetime of 3–10 min and is deduced to be the key antibacterial species. Finally, the chemical profile of EtOH decomposition in the Ar+EtOH+O2 plasma jet is deduced and compared with that in the Ar+EtOH plasma jet. [ABSTRACT FROM AUTHOR]

Aqueous reactive species induced by gas plasmas play a dominant role in many plasma applications such as water purification and biomedicine, but their production mechanism is so far not well understood. In this paper, an experimental setup is designed to study the interaction between an AC helium plasma jet and PBS, which allows a decoupling analysis of the plasma-liquid processes on the production of aqueous reactive species. The processes include the dissolution of neutral reactive species, the electron absorption by dissolved oxygen, the deposition of positive ions, etc. Four aqueous reactive species including H2O2, OH and peroxynitrite (ONOOH/ONOO−) are detected, among which the peroxynitrite should originate from the air impurity in helium. It is found that the aqueous H2O2 and peroxynitrite are mainly dissolved from the gas phase, the aqueous is mainly generated by the electron absorption by dissolved oxygen, and the aqueous OH is mainly generated by the deposition of positive ions. [ABSTRACT FROM AUTHOR]

In this paper, a one-dimensional fluid model of He + O2 dielectric barrier discharge is established. As the oxygen concentration increases from 0.2% to 0.7% and 1.2%, the plasma transforms from triple-breakdowns to single-breakdown per half-cycle. In the mode of multi-breakdowns, the first pulse produces more particles although dissipates more power, thus making remarkable differences in the energy efficiencies in producing charged species but can hardly affect neutral species. We also operate the model in another way that the plasma is held in the mode of single-breakdown, by changing the oxygen concentration and voltage amplitude at the same time, so the impact of mode transformation is removed. In this way, the production efficiency of the electron decreases significantly, probably owing to the enhanced electron attachment with O2 and O3. After analyzing the main chemistry process of both charged and neutral species, it is suggested that the decreasing efficiency of the electron and the increasing oxygen concentration impose opposite impacts on the energy efficiencies of other species. Almost all charged species decrease more or less in their efficiencies, but O3- is the exception. For neutral species, the efficiencies vary slightly for O and O* but increase more than 250% for O2* and O3. [ABSTRACT FROM AUTHOR]

In this paper atmospheric-pressure rf He+O2 cold plasmas are studied by means of a 1-D fluid model. 17 species and 60 key reactions selected from a study of 250+ reactions are incorporated in the model. O2+, O3-, and O are the dominant positive ion, negative ion, and reactive oxygen species, respectively. Ground state O is mainly generated by electron induced reactions and quenching of atomic and molecular oxygen metastables, while three-body reactions leading to the formation of O2 and O3 are the main mechanisms responsible for O destruction. The fraction of input power dissipated by ions is ∼20%. For the conditions considered in the study ∼6% of the input power is coupled to ions in the bulk and this amount will increase with increasing electronegativity. Radial and electrode losses of neutral species are in most cases negligible when compared to gas phase processes as these losses are diffusion limited due to the large collisionality of the plasma. The electrode loss rate of neutral species is found to be nearly independent of the surface adsorption probability p for p > 0.001 and therefore plasma dosage can be quantified even if p is not known precisely. [ABSTRACT FROM AUTHOR]

Biofilm infections in wounds seriously delay the healing process, and methicillin-resistant Staphylococcus aureus is a major cause of wound infections. In addition to inactivating micro-organisms, low-temperature gas plasma can restore the sensitivity of pathogenic microbes to antibiotics. However, the combined treatment has not been applied to infectious diseases. In this study, low-temperature gas plasma treatment promoted the effects of different antibiotics on the reduction of S. aureus biofilms in vitro. Low-temperature gas plasma combined with rifampicin also effectively reduced the S. aureus cells in biofilms in the murine wound infection model. The blood and histochemical analysis demonstrated the biosafety of the combined treatment. Our findings demonstrated that low-temperature gas plasma combined with antibiotics is a promising therapeutic strategy for wound infections. [ABSTRACT FROM AUTHOR]