Search Results (199)

Control of reactive species generation lies at the core of atmospheric pressure plasma processing. In this work, we investigate the ability of a cold RF argon plasma jet source to produce reactive oxygen and nitrogen species (RONS) following the injection of a molecular gas (N₂ or O₂), either premixed with the main gas (Ar) or introduced separately into an already generated Ar discharge. We show that, when reactive gases are injected directly into the Ar discharge, the range of operating parameters—particularly the ratio of reactive gas to main gas—is considerably widened compared to conventional injections through the main argon flow. The plasma characteristics at the source exit were analyzed using optical emission spectroscopy (OES), including the determination of electron density, rotational temperature, and the emission intensities of plasma species such as Ar I, NO(A), OH(A), and N₂(C) for both injection types. Overall, the results show that plasmas generated using in-discharge injection are more stable and capable of sustaining enhanced production of reactive radicals such as NO(A) and OH(A), whereas injection through the main gas can be tuned to selectively enhance NO generation. These findings highlight the potential of plasma sources employing premixed or in-discharge reactive gas injection for surface treatment and for the processing of gas and liquid phases. Full article

This work presents a multifactorial strategy for reusing waste thermoplastics and generating multifunctional filaments for additive manufacturing. Acrylonitrile–butadiene–styrene (ABS) waste and commercial poly(methyl methacrylate) (PMMA) were compounded with carbon black (CB), graphene (G), or graphene foam (GF) at different loadings and extruded into composite filaments. The aim is to couple filler-induced bulk modifications with atmospheric pressure plasma jet (APPJ) surface coatings of TiO₂ and graphene oxide (GO) to obtain waste-derived filaments with tunable morphology, wettability, and thermal stability for advanced 3D-printed architectures. The filaments were subsequently coated with TiO₂ and/or GO using an APPJ process, which tailored surface wettability and enabled the formation of photocatalytically relevant interfaces. Digital optical microscopy and SEM revealed that CB, G, and GF were reasonably well dispersed in both polymer matrices but induced distinct surface and cross-sectional morphologies, including a carbon-rich outer crust in ABS and filler-dependent porosity in PMMA. For ABS composites, static contact-angle measurements show that APPJ coatings broaden the apparent wettability window from ~60–80° for uncoated filaments to ~40–50° (TiO₂/GO) up to >90° (GO), corresponding to a ≈150% increase in contact-angle span. For PMMA/CB composites, TiO₂/GO coatings expand the accessible contact-angle range to ~15–125° while maintaining surface energies around 50 mN m⁻¹. TGA/DSC analyses confirm that the composites and coatings remain thermally stable within typical extrusion and APPJ processing ranges, with graphene showing only ≈3% mass loss over the explored temperature range, compared with ≈65% for CB and ≈10% for GF. Fused deposition modeling trials verify the printability and dimensional fidelity of ABS-based composite filaments, whereas PMMA composites were too brittle for reliable FDM printing. Overall, combining waste polymer reuse, tailored carbonaceous fillers, and APPJ TiO₂/GO coatings provides a versatile route to design surface-engineered filaments for applications such as photocatalysis, microfluidics, and soft robotics within a circular polymer manufacturing framework. Full article

Background: Glucose, a central carbohydrate in higher organisms’ metabolism, can undergo extensive oxidative modification under conditions of excessive inflammation or elevated reactive oxygen and nitrogen species (RONS). Such modifications yield glucose oxidation products (GOPs) with potential biological relevance and toxicity. This study aimed to systematically characterize GOP formation under defined oxidative conditions generated by gas plasma treatment. Methods: D-glucose solutions were prepared at 0.25 mM (hypoglycemic/diabetic range), 2.5 mM (sub-physiological), and 25 mM (peritoneal dialysis fluid). Samples were exposed for up to 20 min to the atmospheric-pressure argon plasma jet kINPen, which produces a wide spectrum of RONS. Treatment time-dependent glucose oxidation was assessed by high-resolution mass spectrometry (HRMS) and tandem mass spectrometry (MS/MS) to identify the oxidation products. Results: Gas plasma exposure generated various oxidation products and their abundance profiles depended on initial glucose concentration and treatment duration. Identified products included 2-keto-D-glucose, 3-deoxyglucosone (3DG), 3,4-dideoxyglucosone-3-ene (3,4DGE), furaldehyde, methylglyoxal, and acetaldehyde. HRMS/MS analysis confirmed diagnostic fragment ions for each GOP and revealed distinct formation across the model scenarios. Conclusions: Cold gas plasma induces a spectrum of glucose oxidation products under biomedically relevant glucose levels. The identified GOPs, many of which have known cytotoxic or signaling properties, provide mechanistic insight into glucose oxidation in inflamed or oxidative microenvironments. These findings support the utility of plasma-based oxidative models for studying GOP-associated biological effects and potential pathophysiological consequences. Full article

The atmospheric pressure plasma jet (APPJ) is a popular type of cold atmospheric plasma (CAP). APPJs based on a pulsed atmospheric arc (PAA) are widely spread in industrial processing. A plasma jet of this type, PlasmaBrush PB3 (PB3), is a subject of diverse research activities. The characteristic feature of PB3 is the generation of a low-current (300 mA), high-voltage (1500 V) pulsed (54 kHz) atmospheric arc. A gas flow vortex is used to stabilize the arc and to sustain the circular motion of the cathodic arc foot. During long periods of operation, nozzles acting as arc discharge cathodes erode. Part of the eroded material is emitted as nanoparticles (NPs). These NPs are not wanted in many processing applications. Knowledge of the number, type, and size distribution of emitted NPs is essential to minimize their emissions. In this study, NPs in the size range of 6 to 220 nm, emitted from four different nozzles operated with PB3, are investigated. The differences between the nozzles are in the eroded surface material (copper, tungsten, and nickel), the diameter of the nozzle orifice, the length of the discharge channel, and the position of the cathodic arc foot. Significant differences in the particle size distribution (PSD) and particle mass distribution (PMD) of emitted NPs are observed depending on the type and condition of the nozzle and their operating time. Monomodal and bimodal PMD models are used to approximate emissions from the nozzles with tungsten and copper cores, respectively. The skew-normal distribution function is deemed suitable. The results of this study can be used to control NP emissions, both to avoid them and to utilize them intentionally. Full article

This review presents recent advancements in cold atmospheric pressure (AP) plasma (CAP) processes for the synthesis and surface treatment of polymer films and metal nanoparticles (NPs) in biomedical applications. We discuss the properties and applications of atmospheric pressure plasma (APP) processes, including dielectric barrier discharge (DBD) and plasma jet methods, highlighting their effectiveness in controlling surface characteristics such as wettability and functionalization. Full article

This research presents an experimental analysis of the influence of atmospheric pressure plasma on the performance of a micro horizontal-axis wind turbine blade. The investigation was conducted using an NACA 4412 airfoil equipped with a dielectric barrier discharge (DBD) plasma actuator. The electrodes were configured asymmetrically, with a 2 mm gap and copper electrodes that are 0.20 mm in thickness. A high voltage of 6 kV was applied, resulting in a current of 0.071 mA and a power output of 0.426 W. Optical emission spectroscopy identified the excited components through the interaction of the high-voltage AC electric field with air molecules: ${\mathrm{N}}_2$, ${\mathrm{N}}_2^{+}$, ${\mathrm{O}}_2^{+}$, and O. The electrohydrodynamic force mainly results from the observed charged ions that, when accelerated by the electric field, transfer momentum to neutral molecules via collisions, leading to the formation of the observed jet plasma. The findings indicated a notable enhancement in aerodynamic performance attributable to the electrohydrodynamic (EHD) flow generated by the plasma. The estimated electrohydrodynamic force ($8.712\times {10}^{-4}$ N) is capable of maintaining the flow attached to the airfoil surface, thereby augmenting flow circulation and, consequently, enhancing the lift force. According to blade element theory, the lift and drag coefficients directly influence the torque and mechanical power generated by the wind turbine rotor. Schlieren imaging was utilized to observe alterations in air density and flow patterns. Lissajous curve analysis was used to examine the electrical discharge behavior, showing that only 7.04% of the input power was converted into heat. This indicates that nearly all input electric energy was transformed into EHD force by the atmospheric pressure plasma. Compared to traditional aerodynamic control methods, DBD actuators are a feasible alternative for small wind turbines due to their lightweight design, absence of moving parts, ability to be surface-embedded without altering blade geometry, and capacity to generate active, dynamic flow control with reduced energy consumption. Full article

Volvariella volvacea, a fungal species of Volvariella within the Pluteaceae family, is predominantly cultivated in southern China. Polysaccharides, the primary bioactive constituents of V. volvacea, exhibit diverse pharmacological activities. However, current cultivation practices face challenges due to the genetic heterogeneity of strains, leading to inconsistent content and compositional variability of polysaccharides and other functional components. ARTP, denoting atmospheric and room-temperature plasma, is a technology capable of generating plasma jets at ambient pressure with temperatures ranging from 25 to 40 °C. These jets feature high concentrations of highly reactive species, including but not limited to excited-state helium atoms, oxygen atoms, nitrogen atoms, and OH radicals. This study aims to develop high-yielding exopolysaccharide (EPS) strains through integrated ARTP mutagenesis and genome shuffling, thereby overcoming current cultivation bottlenecks. ARTP mutagenesis and genome shuffling significantly boosted EPS production in V. volvacea. ARTP generated nine stable mutants with >20% higher EPS yields. Subsequent genome shuffling (three rounds of protoplast fusion) produced the hybrid strain SL212, which achieved 46.85 g/L of EPS, an 111.67% increase over that of the parent strain under identical conditions. Metabolomics and transcriptomics analyses revealed that differential metabolites and genes were mainly enriched in galactose metabolism, ABC transporter pathways, and the tricarboxylic acid cycle. These pathways enhance monosaccharide biosynthesis and generate ATP, providing both precursors and energy for polysaccharide polymerization, thereby driving EPS overproduction. Preliminary mechanistic analysis identified the key contributing factors driving the elevated polysaccharide biosynthesis. Full article

Atmospheric pressure plasma jets (APPJs) enable efficient solvent-free surface modification to enhance the wettability, adhesion, and biocompatibility of polymers. However, conventional APPJs often generate high temperatures and energetic particles, which lead to melting, surface degradation, and molecular damage of thermosensitive polymers, thus limiting their scope of application. This study demonstrates an optimized atmospheric pressure microwave plasma jet (MPJ) operating at 8 W microwave power, achieving gas temperatures as low as 27.5 °C—only 2 °C above ambient. Direct skin contacts with the plasma jet for 150 s resulted in a maximum temperature of 35 °C without discomfort. In addition, the MPJ significantly enhances the surface hydrophilicity of TPU, PVC, and POM materials without causing damage. The designed MPJ has low gas temperature and good discharge stability, providing a new solution for plasma surface modification of thermosensitive materials. Full article

While atmospheric pressure plasma sources are emerging as potentially innovative instruments in medicine, some aspects of the interaction between plasma and biological substrates remain unclear. The high diversity in both sources and applications in the literature, and the lack of a systematic testing protocol, has resulted in a wide variety of devices that cannot be efficiently compared with one another. In this work, an integrated benchmark involving physical, chemical, and biological diagnostics is proposed. The setup is designed to be stable and fixed, while remaining adaptable to different sources. Three different sources, for a total of five configurations, are compared, demonstrating the possibility of obtaining multimodal data. Comparing the biological effects in terms of E. coli abatement between direct and indirect treatments allowed for the exclusion of short-timescale species and phenomena to have a key role in the abatement. The chemical characterisation describes the equilibrium of reactive oxygen and nitrogen species in treated samples, whose presence in the water has been found to be coherent with the plasma operating gas and the nitrogen vibrational temperatures. Nitrate, nitrite and peroxide are excluded from having an autonomous role in the inactivation biochemistry, suggesting the presence of a synergistic effect. Full article

The scope of the antibacterial effects of plasma-activated water (PAW) is not yet fully comprehended. We investigated the activity of PAW produced by the in-house 3-pin atmospheric pressure plasma jet against carbapenem-resistant Klebsiella pneumoniae and vancomycin-resistant Enterococcus faecalis, with a focus on PAW’s potential to promote susceptibility to conventional antibiotics in these bacteria. Bacterial inactivation was determined by the colony count after 15 and 60 min PAW treatments. Minimum inhibitory concentrations (MICs) measured following repeated exposures to PAW across multiple generations of bacteria enabled the assessment of changes in susceptibility to antibiotics. The PAW’s efficacy was also analyzed through the detection of intracellular reactive oxygen and nitrogen species in treated bacteria. Time-dependent significant inactivation efficiency against K. pneumoniae was observed (log reduction 6.92 ± 0.24 after 60 min exposure), while effects on E. faecalis were limited. PAW demonstrated potential to decrease the MICs of crucial antibiotics. Namely, a 50 to 62.5% decrease in the MICs of colistin against K. pneumoniae and a 25% reduction in the MICs of vancomycin against enterococci were recorded. We found a significant increase in the superoxide anion concentration in K. pneumoniae and E. faecalis cells after PAW treatments. This study indicates that PAW’s inactivating efficacy coupled with the capacity for the potentiation of antibiotic effects is a promising combination against multidrug-resistant bacteria. Full article

We report the formation of multi-walled carbon nanotubes (MWCNTs) through the interaction of an atmospheric-pressure plasma jet, generated via a capillary discharge, with a graphite surface. The structural properties of MWCNTs on the graphite anodes demonstrated a clear dependence on discharge power. Utilizing scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy, we observed a progression toward the disordering and interconnection of the nanotubes alongside the emergence of graphitized clusters with increasing discharge energy. The formation of relatively defect-free MWCNTs at minimal discharge energy presents an opportunity for their synthesis with low energy consumption of 4.7 kJ/cm². The suggested energy-efficient, rapid, and straightforward technique for tailoring MWCNT formation significantly reduces the reliance on complex and expensive instrumentation, presenting a promising pathway for effective surface modification. Full article

Black locust (Fabaceae family) seeds are known for their strong dormant state and are an excellent candidate for studying and developing methods to break dormancy. We investigated overcoming the dormancy using several different sources of non-thermal plasma, which, by modifying, etching, or disrupting the waxy seed coat, allowed water to penetrate the seeds and initiate germination. All plasma sources tested enhanced seed germination to varying degrees, with over 80% germination observed when using a dielectric barrier discharge, while control seeds showed no germination. Non-thermal plasma treatment significantly decreased the water contact angle of the seed surface from an initial 120° (for untreated seeds) to complete wetting when using a dielectric barrier discharge or atmospheric-pressure plasma jet. The experiments indicate two mechanisms for the modification of the waxy seed coat by a non-thermal plasma: hydrophilization of the wax surface through the binding of oxygen particles and etching of narrow channels in the wax layer, allowing water to penetrate the seed. Full article

Cold atmospheric plasma (CAP) treatment induces cancer cell death through the generation of reactive oxygen and nitrogen species (RONS). However, the efficacy of RONS delivery into cells remains limited by membrane permeability. Here, we investigated whether combining CAP with pulsed electric fields (PEFs) could enhance cancer cell death through increased intracellular RONS uptake. HeLa cells were treated with argon atmospheric pressure plasma jet (Ar-APPJ), PEF, or their combination. The combined treatment showed significantly enhanced cell death compared to single treatments. While PEF treatment alone induced membrane permeabilization, the combination with Ar-APPJ resulted in more pronounced and sustained membrane disruption, as evidenced by increased calcein leakage. This enhanced effect was attributed to Ar-APPJ-induced lipid peroxidation interfering with membrane resealing after PEF-induced electroporation. We also demonstrated that PEF-induced membrane electroporation facilitates the intracellular uptake of CAP-generated RONS. These findings provide mechanistic insights into the synergistic effects of combined CAP and PEF treatments, suggesting enhanced cell death via multiple pathways. Full article

In view of a constant growth in the human population on Earth, the provision of a necessary amount of high-quality food looks challenging. As over 10% of the crop yields are annually lost due to the presence of phytopathogens, the development of novel, eco-friendly methods of pest eradication might contribute to avoiding nutritional shortages. Here, we propose a controlled application of cold atmospheric pressure plasma (CAPP) generated in the form of an atmospheric pressure plasma jet (APPJ), for which we conducted multivariate optimization of the working parameters with the use of the design of experiments (DoE) in addition to the response surface methodology (RSM). After estimating the optimal operating conditions of APPJ, we determined the inactivation rates caused by 2 min CAPP exposure towards bacterial phytopathogens from three species Dickeya solani, Pectobacterium atrosepticum and Pectobacterium carotovorum artificially inoculated on the surface of plant seeds from four species. Logarithmic reductions, as a key result of this work, were enclosed in the range of 1.61–4.95 in the case of Cucumis sativus, Pisum sativum, and Vigna radiata, while for the bacteria-inoculated Zea mays seeds, lower antibacterial properties of APPJ equaling 0.86–1.12 logs were noted. The herein applied exposure to APPJ did not reveal any statistically significant detrimental effects on the germination of plant seeds, seed coat integrity, or early plant growth. Even plant growth promotion by 20.96% was observed for the APPJ-exposed Zea mays seeds. By applying colorimetric assays and optical emission spectrometry (OES), we determined the oxidative potential in addition to identifying the reactive oxygen species (ROS) ^•OH, ^•HO₂, ^•O₂⁻, O₃, and ¹O₂ and the reactive nitrogen species (RNS) N, NO₂, and NO₃ responsible for the antibacterial properties of APPJ. In summary, universal antiphytopathogenic properties of the APPJ treatment reached due to proper optimization of the working conditions were revealed against three bacterial strains from the family Pectobacteriaceae inoculated on the seeds from diverse plant species. The data presented herein may contribute to future development of the plasma agriculture field and provide alternatives to pesticides or the prevention-based control methods towards plant pathogenic bacteria. Full article

The industrial and artisanal textile industries necessitate the adoption of sustainable dyeing practices. Although the natural dye derived from Dactylopius coccus presents a viable option, its traditional application requires metallic mordants that pose environmental and health risks. This study investigates the utilization of atmospheric-pressure plasma jet (APPJ) technology for dyeing wool with Dactylopius coccus dye, with the objective of optimizing the process and minimizing its environmental impact. The APPJ technique was employed for wool dyed with Dactylopius coccus dye, and the textile properties, medullation, and colorimetry were evaluated using an optical fiber diameter analyzer (OFDA) and a spectrometer with an integrating sphere. The results demonstrated that the APPJ enhanced the color intensity and uniformity, facilitating improved dye penetration into the fibers. Plasma treatment darkened the fiber, generated reddish and yellowish tones, and increased the color saturation and intensity. The wool samples treated with plasma exhibited an increase in DMF and SF but a decrease in IC and greater size variability. The APPJ reduces total medullation in wool dyed with cochineal dye. In conclusion, the APPJ was demonstrated to be a promising method for dyeing wool with Dactylopius coccus dye, offering an effective and sustainable alternative to traditional methods, with enhanced color vibrancy and uniformity and reduced resource utilization. Full article