Search Results (97)

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

Tracheal stenosis (i.e., the abnormal narrowing of the trachea) can occur due to a variety of inflammatory and infectious processes as well as due to therapeutic procedures undertaken by the patient. The most common cause of tracheal obstruction in patients has been prolonged intubation. Depending on the extent of the stenosis and its exact location, the surgical insertion of a tracheal stent is the only option for addressing this issue. The Montgomery T-tube implant is a valuable tracheal stent made from medical-grade silicone that provides a functional airway while supporting the tracheal mucosa. However, its performance is subject to gradual deterioration due to biofilm colonization of the stent’s inner wall, which may explain the discomfort claimed by many patients and clinical failures. Recently, cold atmospheric plasmas (CAPs) have emerged as an alternative technology to many conventional medical procedures, such as wound healing, skin treatment, decontamination of medical devices, etc. Here, we report on plasma-induced surface modification of the inner wall of a T-tube implant, considering future biomedical applications. To generate the plasma, we employed a cold atmospheric pressure plasma jet in gas helium, which was directly inserted into the T-tube implant. To assess the treatment uniformity, the degree of surface modification and its extension along the stent’s inner wall was analyzed using different process parameters. Full article

Oral mucositis associated with candidiasis can causes systemic candidemia, posing a risk to cancer patients administered antineoplastic therapy. Cold atmospheric pressure plasma jets (CAPPJs) have antifungal and anti-inflammatory properties. This study evaluated the effects CAPPJs in preventing systemic fungal dissemination in a murine model of oral mucositis associated with candidiasis. Forty Wistar rats were divided into groups: CAPPJs (treated) and non-treated controls (for comparison), with subgroups subject to 24 and 72 h of treatment (n = 10 each). Four cycles of chemotherapy (cisplatin and 5-fluorouracil (5-FU)) were administered, followed by oral inoculation of Candida albicans for 3 days. Mucosal damage was induced on the lateral side of tongue with 50% acetic acid. CAPPJ treatment was performed on the lesion for 5 min (2 days). Body weight was assessed daily. Fungal dissemination was conducted using organ macerates and plated on Sabouraud Agar with chloramphenicol. Blood samples were obtained for blood count tests. Chemotherapy affected the general health of the animals, as evidenced by body weight loss. Treatment with CAPPJs showed an inhibitory effect on C. albicans, with a significant reduction in fungal recovery from the tongue after 24 h (p < 0.05). Interestingly, systemic fungal dissemination was significantly reduced after 24 and 72 h of treatment when compared to control (p < 0.05). Taken together, these results suggest that CAPPJs have potential for clinical application in patients with oral mucositis at risk of candidemia. Full article

This study evaluated the effectiveness of atmospheric pressure plasma jet (APPJ) treatment on the surface characteristics and bond strength of zirconia and lithium disilicate ceramics for CAD-on restorations. A total of 70 cylindrical-shaped specimens of lithium disilicate and 70 disc-shaped specimens of Y-TZP zirconia were machined, thermally processed, surface-treated, and then resin-bonded. The specimens were grouped according to the following surface treatments: no surface treatment, sandblasting, plasma, sandblasting followed by plasma, sandblasting followed by universal adhesive, plasma followed by universal adhesive, and sandblasting and plasma treatment followed by universal adhesive. The treated surfaces were subjected to a wettability assessment via contact angle measurement and a topography assessment using scanning electron microscopy (SEM). The cemented assembly was subjected to shear bond strength testing with a universal testing machine, and the results were imported to SPSS 23.0 for statistical analysis. The results show that APPJ treatment induced a significantly low contact angle for both ceramics with no surface alteration upon scanning. Moreover, APPJ treatment produced a bonded assembly with a shear bond strength comparable to sandblasting. In conclusion, APPJ treatment should be considered an efficient surface treatment with a non-destructive nature that surpasses sandblasting with the provision of a high shear bond strength between CAD-on ceramics. Full article

Atmospheric pressure plasma jets (APPJs) have attracted significant attention due to their ability to generate plasma without vacuum systems, facilitating their use in small areas of plasma processing applications across various fields, including medicine, surface treatment, and agriculture. In this study, we investigate the interaction between two helium plasma jets, focusing on the effects of varying flow rate, voltage, and directional angle. By examining both in-phase and out-of-phase configurations, this research aims to elucidate the fundamental mechanisms of plasma plume merging, which has critical implications for optimizing plasma-based material processing systems. We demonstrate that while increasing voltage and flow rate for the in-phase condition leads to an extended plasma plume length, the plumes do not merge, maintaining a minimal gap. Conversely, plasma plume merging is observed for the out-of-phase condition, facilitated by forming a channel between the jets. This study further explores the impact of these merging phenomena on plasma chemistry through optical emission spectroscopy, revealing substantial differences in the emission intensities of OH, the second positive system of ${\mathrm{N}}_2$, and the first negative system of ${\mathrm{N}}_2^{+}$. These findings offer valuable insights into controlling plasma jet interactions for enhanced efficiency in plasma-assisted processes, particularly where plume merging can be leveraged to improve the treatment area and intensity. Full article

The Solid-State Linear Transformer Driver (SSLTD) is a nanosecond pulse power source characterized by its fast rise time and adjustable output waveform. It can generate uniform and stable atmospheric plasma jets, which is suitable for material surface modification. In this study, a 15-stage SSLTD was designed and assembled, which can produce a stable nanosecond pulse voltage up to 15 times the amplitude of the charging voltage at high frequencies, with a rise time of approximately 10 ns. This device can be used to generate stable atmospheric pressure Ar plasma jets with an electron density in the range of 10¹⁵~10¹⁶ cm⁻³ and gas temperatures close to room temperature. After the modification treatment by the plasma jets, the content of the C=O groups on the surface of the epoxy resin significantly increased in the wavelength range of 1720~1740 cm⁻¹, and its flashover resistance was noticeably enhanced. The optimal comprehensive modification effect was achieved at a charging voltage of 600 V, pulse width of 50 ns, and pulse frequency in the range of 800~1000 Hz. Full article

The use of Atmospheric Pressure Plasma Jet (APPJ) technology for surface treatment of carbon fabrics is investigated to estimate the increase in the fracture toughness of carbon-fiber composite materials. Nitrogen and a nitrogen–hydrogen gas mixture were used to size the carbon fabrics by preliminarily optimizing the process parameters. The effects of the APPJ on the carbon fabrics were investigated by using optical and chemical characterizations. Optical Emission Spectroscopy, Fourier Transform Infrared-Attenuated Total Reflection, X-ray Photoelectron Spectroscopy and micro-Raman spectroscopy were adopted to assess the effectiveness of ablation and etching effects of the treatment, in terms of grafting of new functional groups and active sites. The treated samples showed an increase in chemical groups grafted onto the surfaces, and a change in carbon structure was influential in the case of chemical interaction with epoxy groups of the epoxy resin adopted. Flexural test, Double Cantilever Beam and End-Notched Flexure tests were then carried out to characterize the composite and evaluate the fracture toughness in Mode I and Mode II, respectively. N₂/H₂ specimens showed significant increases in G_IC and G_IIC, compared to the untreated specimens, and slight increases in P_max at the first crack propagation. Full article

We fabricate lithium tin-based oxide Li₂SnO₃ on carbon cloth from a gel-state precursor containing LiCl and SnCl₂·2H₂O using a nitrogen atmospheric-pressure plasma jet (APPJ). APPJ treatment provides both a high-temperature environment for the conversion of precursor into Li₂SnO₃ and nitrogen plasma reactive species for electrode surface modification. Here, the best electrochemical performance for the Li₂SnO₃ Li-ion hybrid supercapacitors (Li–HSCs) is achieved with 480 s of APPJ processing. The areal capacity of the 480 s APPJ-processed Li₂SnO₃ Li–HSCs reached 46.113 mC/cm². The results indicate that APPJ is an effective tool for the rapid conversion processing of Li₂SnO₃ electrodes for Li–HSCs. Full article

The extensive utilization of dyes across diverse industries has resulted in environmental pollution, leading to the degradation of water bodies. To prevent environmental contamination, the use of eco-friendly dyes and innovative processes for dye degradation is crucial. This study aimed to investigate the color removal process of cochineal dye (Dactylopius coccus Costa) using the atmospheric pressure plasma jet (APPJ: Atmospheric Pressure Plasma Jet) technique. The dye extracted from the cochineal insect was treated with APPJ and the resulting color removal process was analyzed. Optical emission spectroscopy (OES) was used to investigate the plasma emission lines, and UV-Vis spectroscopy was used to monitor the color removal process. The results revealed that the decolorization of cochineal dye was a result of an oxidative degradation process caused by the interaction of the reactive species (NO₃⁻ and NO₂⁻) generated by the APPJ plasma discharge with the dye molecules. This color removal process occurs in an acidic medium, leading to a pH change from 5.4 to 2.7. These pH changes can be attributed to fluctuations in the concentrations of reactive species such as nitrates and nitrites in the liquid phase. UV-Vis spectroscopy measurements showed that 90% of the cochineal color was removed within the first 10 min of treatment. This study enhances our understanding of natural color removal and provides insights into its mechanism, opening up possibilities for controlled modification and applications in various fields. Full article

Methicillin-resistant Staphylococcus aureus (MRSA) often causes serious infections in hospitals. Vancomycin is widely accepted as the standard therapy for MRSA infection, but its widespread use has resulted in the generation of vancomycin-resistant S. aureus (VRSA). To reduce the potential risk of MRSA and VRSA emergence in aquatic environments, we investigated the degradation of methicillin and vancomycin by cold atmospheric pressure plasma jet (APPJ) irradiation using N₂, O₂, and CO₂ gases. The concentrations of methicillin and vancomycin in distilled water were decreased in a time-dependent manner by the plasma jet irradiation; that is, compared with the pre-treatment levels, the concentrations of methicillin and vancomycin were reduced by 20 to 50% after plasma jet irradiation for 10 s. No methicillin and vancomycin signals were detected after 300 s irradiation. Reactive species generated from the plasma jet electrophilically attacked and fragmented the antibiotic molecules. The present method realizes direct plasma ignition in a solution, and therefore, the reactive species can easily react with antibiotic molecules. In addition, plasma can be generated from various gas species that are abundant in the atmosphere. Therefore, cold APPJ irradiation can be a powerful, cost-effective, and environmentally friendly means for the treatment of antibiotics in aqueous samples. Full article