Cold Atmospheric Plasma Research Articles

High-efficiency and low-damage modification of engineering metal materials by oxygen-mixing atmospheric pressure cold plasma jets

Engineering metal materials have been widely developed and applied in aviation, aerospace and biomedicine fields. Wettability improvement of these materials can alleviate problems caused by low adhesion and poor bioactivity, thereby facilitating their practical applications. Compared with other methods, atmospheric pressure cold plasma treatment has better versatility and can efficiently improve wettability without causing serious damages, and has therefore been widely used in polymer hydrophilization. However, when treating metal materials, the cold plasma may induce surface breakdown or have low efficiency. In this paper, we developed a new cold plasma jet by mixing oxygen into working gas to achieve high-efficiency and low-damage modification. When oxygen mixing ratio was 0.4 %, the cold plasma jet could modify TC4 titanium alloy surface to be superhydrophilic within 20 s, which was much more efficient than traditional plasma jet (120 s). We then further investigated the mechanism contributing to higher efficiency, and found that the oxygen-mixing plasma jet did not cause serious damages, while generating more polar groups by higher-concentration active particles, as confirmed by surface energy calculation and optical emission spectra. Besides titanium alloy, the oxygen-mixing plasma jet could also achieve rapid hydrophilization of various engineering metal materials, showing promising application prospects.

Trehalose enhanced cold atmospheric plasma-mediated cancer treatment

Cold atmospheric plasma (CAP) is a unique form of physical plasma that has shown great potential for cancer therapy. CAP uses ionized gas to induce lethal oxidative stress on cancer cells; however, the efficacy of CAP therapy continues to be improved. Here, we report an injectable hydrogel-mediated approach to enhance the anti-tumor efficacy of CAP by regulating the phosphorylation of eIF2α. We discovered that reactive oxygen and nitrogen species (ROS/RNS), two main anti-tumor components in CAP, can lead to lethal oxidative stress on tumor cells. Elevated oxidative stress subsequently induces eIF2α phosphorylation, a pathognomonic marker of immunogenic cell death (ICD). Trehalose, a natural disaccharide sugar, can further enhance CAP-induced ICD by elevating the phosphorylation of eIF2α. Moreover, injectable hydrogel-mediated delivery of CAP/trehalose treatment promoted dendritic cell (DC) maturation, initiating tumor-specific T-cell mediated anti-tumor immune responses. The combination therapy also supported the polarization of tumor-associated macrophages to an M1-like phenotype, reversing the immunosuppressive tumor microenvironment and promoting tumor antigen presentation to T cells. In combination with immune checkpoint inhibitors (i.e., anti-programmed cell death protein 1 antibody, aPD1), CAP/trehalose therapy further inhibited tumor growth. Importantly, our findings also indicated that this hydrogel-mediated local combination therapy engaged the host systemic innate and adaptive immune systems to impair the growth of distant tumors.

Cold atmospheric pressure plasma assisted rapid assembly of peptide-based structures: a molecular scaffold to form supramolecular architectures

The use of cold atmospheric pressure plasma (CAPP) technology in the production of peptide-based materials has shown great potential in modern technology. Herein, two aggregation-prone oligopeptides, GNNQQNY and KLVFFA, were subjected to CAPP treatment to form supramolecular assemblies/aggregates. Through peptide engineering and biophysical techniques, the effect of CAPP-generated reactive oxygen and nitrogen species on the oligopeptides were investigated for different treatment times revealing that the formation of these aggregates were primarily driven by electrostatic interactions without any chemical modifications. Field emission-scanning electron microscopy and Thioflavin T (ThT) binding assay confirmed the presence of distinct β-strands, particularly in the aggregates of the KLVFFA peptide upon CAPP irradiation. The combination of CAPP technology with peptide self-assembly process and the characterization techniques employed in this study holds promise for the development of such peptide supramolecular structures based on the specific amino acid sequences.

Evaluating atmospheric pressure cold plasma decontamination techniques for packaging materials: a systematic review and meta-analysis

Evaluating atmospheric pressure cold plasma decontamination techniques for packaging materials: a systematic review and meta-analysis

Cold Plasma Deposition of Tobramycin as an Approach to Localized Antibiotic Delivery to Combat Biofilm Formation.

Hospital-acquired infections (HAIs) remain a significant factor in hospitals, with implant surfaces often becoming contaminated by highly resistant strains of bacteria. Recent studies have shown that electrical plasma discharges can reduce bacterial load on surfaces, and this approach may help augment traditional antibiotic treatments. To investigate this, a cold atmospheric plasma was used to deposit tobramycin sulphate onto various surfaces, and the bacterial growth rate of K. pneumoniae in its planktonic and biofilm form was observed to probe the interactions between the plasma discharge and the antibiotic and to determine if there were any synergistic effects on the growth rate. The plasma-deposited tobramycin was still active after passing through the plasma field and being deposited onto titanium or polystyrene. This led to the significant inhibition of K. pneumoniae, with predictable antibiotic dose dependence. Separate studies have shown that the plasma treatment of the biofilm had a weak antimicrobial effect and reduced the amount of biofilm by around 50%. Combining a plasma pre-treatment on exposed biofilm followed by deposited tobramycin application proved to be somewhat effective in further reducing biofilm growth. The plasma discharge pre-treatment produced a further reduction in the biofilm load beyond that expected from just the antibiotic alone. However, the effect was not additive, and the results suggest that a complex interaction between plasma and antibiotic may be at play, with increasing plasma power producing a non-linear effect. This study may contribute to the treatment of infected surgical sites, with the coating of biomaterial surfaces with antibiotics reducing overall antibiotic use through the targeted delivery of therapeutics.

Cold atmospheric plasma attenuates skin cancer via ROS induced apoptosis.

Cold atmospheric plasma (CAP) has been widely used in biomedical research, especially in vitro cancer therapy. Cutaneous squamous cell carcinoma (CSCC) is a malignant tumor originating from epidermal keratinocytes. However, the mechanism of CAP therapy on CSCC remains unclear. The animal models of CSCC induced by 7,12-dimethylbenz(a) anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) were constructed. For the CAP treatment group, after each TPA application, CAP was administered for 3min twice weekly after drying. HE staining were used to detect the pathological status of tumor tissue in each group. The levels of PCNA, Bcl-2, Bax, MMP2 and MMP9 were evaluated by western blot and qPCR. TUNEL staining were used to detect apoptosis in tumor tissues. In vivo, serum samples were used for ELISA of total ROS. MTT assay was used to detect the viability of A431 cells. Western blot and qPCR were used to detect the levels of PCNA, Bcl-2, Bax, MMP2 and MMP9 in A431 cells. A431 cell proliferation was examined by colony formation assay. The proportions of apoptosis of A431 cells were detected by flow cytometry. Transwell assessed the ability of A431 cells migration and proliferation. We found that CAP could induce skin cancer cells apoptosis and inhibit the progress of skin cancer. Through experiments in vitro, reactive oxygen species (ROS) generated by N-acetylcysteine (NAC) and CAP inhibited the proliferation and migration of A431 skin cancer cells while promoting apoptosis. These evidences suggest the protective effect of CAP in CSCC, and CAP has the potential clinical application of CSCC.

Unveiling the interaction mechanisms of cold atmospheric plasma and amino acids by machine learning

AbstractPlasma medicine has attracted tremendous interest in a variety of medical conditions, ranging from wound healing to antimicrobial applications, even in cancer treatment, through the interactions of cold atmospheric plasma (CAP) and various biological tissues directly or indirectly. The underlying mechanisms of CAP treatment are still poorly understood although the oxidative effects of CAP with amino acids, peptides, and proteins have been explored experimentally. In this study, machine learning (ML) technology is introduced to efficiently unveil the interaction mechanisms of amino acids and reactive oxygen species (ROS) in seconds based on the data obtained from the reactive molecular dynamics (MD) simulations, which are performed to probe the interaction of five types of amino acids with various ROS on the timescale of hundreds of picoseconds but with the huge computational load of several days. The oxidative reactions typically start with H‐abstraction, and the details of the breaking and formation of chemical bonds are revealed; the modification types, such as nitrosylation, hydroxylation, and carbonylation, can be observed. The dose effects of ROS are also investigated by varying the number of ROS in the simulation box, indicating agreement with the experimental observation. To overcome the limits of timescales and the size of molecular systems in reactive MD simulations, a deep neural network (DNN) with five hidden layers is constructed according to the reaction data and employed to predict the type of oxidative modification and the probability of occurrence only in seconds as the dose of ROS varies. The well‐trained DNN can effectively and accurately predict the oxidative processes and productions, which greatly improves the computational efficiency by almost ten orders of magnitude compared with the reactive MD simulation. This study shows the great potential of ML technology to efficiently unveil the underpinning mechanisms in plasma medicine based on the data from reactive MD simulations or experimental measurements.

Cold Plasma Treatment of Little Millet Flour: Impact on Bioactives, Antinutritional Factors and Functional Properties.

This study delves into the transformative effects of atmospheric cold plasma (CP) treatment on little millet flour (LMF), specifically exploring alterations in bioactive compounds, antinutritional factors, and functional properties. Foaming and emulsification properties experienced noteworthy enhancements with plasma treatment, manifesting in significant increases in foaming capacity (up to 51.47 ± 0.49%), foaming stability, emulsification ability, and emulsion stability (up to 47.02 ± 0.35%). The treatment also positively influenced water absorption index and swelling power. Antinutritional factors, including tannins and saponins, exhibited substantial reductions following plasma treatment. Saponin content, for instance, decreased by an impressive 58% after exposure to 20kV for 20min. Conversely, bioactive compounds such as phenolic content and antioxidant activity saw significant increases. Total phenolic content (TPC) rose from 527.54 ± 8.94 to 575.82 ± 3.58mg GAE/100g, accompanied by a remarkable 59% boost in antioxidant activity. Interestingly, plasma treatment did not exhibit a discernible effect on pasting properties. These findings collectively underscore the potential of atmospheric CP treatment as a novel and effective method for enhancing the functional and nutritional attributes of LMF, thereby opening new avenues for its application in food science and technology.

Potential Applications of Cold Atmospheric Plasma (CAP) Technologies to Improve the Phytochemical Content of Fresh Fruits and Vegetables.

Potential Applications of Cold Atmospheric Plasma (CAP) Technologies to Improve the Phytochemical Content of Fresh Fruits and Vegetables.

Recent Developments in the Use of Plasma in Medical Applications

A detailed review of the scientific literature was undertaken to examine the most recent developments in plasma processing in the field of medicine. The first part of the review includes a detailed breakdown of the different types of coatings that can be applied onto medical devices using plasma, with a specific focus on antimicrobial surfaces. The developments in plasma-deposited biocompatibles, drug delivery and adhesive coatings in 2023 are described, and specific applications in additive manufacturing are highlighted. The use of plasma and plasma-activated liquids as standalone therapeutics continues to evolve, and pertinent advances in this field are described. In addition, the combination of plasma medicine with conventional pharmaceutical interventions is reviewed, and key emerging trends are highlighted, including the use of plasma to enhance drug delivery directly into tissue. The potential synergies between plasma medicine and chemotherapeutics for oncology and infection treatment are a growing area, and recent advancements are noted. Finally, the use of plasma to control excess antibiotics and to intentionally degrade such materials in waste streams is described.

Atmospheric cold plasma-induced mortality in Sitophilus oryzae (L.)

The rice weevil, Sitophilus oryzae, is a common pest in grain storage and agriculture, causing considerable damage to stored grains. Increasing resistance of rice weevils to current fumigation methods continues to occur, necessitating the development of alternative control strategies. In this study, we investigated the impact of atmospheric cold plasma (ACP) on the mortality of rice weevils. ACP generates non-thermal ionized gas at or near room temperature and has been effective in inactivating microorganisms and pests, including rice weevils. We hypothesized that ACP treatment would have detrimental effects on the weevils, leading to a high mortality rate. To evaluate this hypothesis, we applied a treatment voltage of 80 kV and treatment times of 0, 3, 5, 8, and 10 min across all life stages of rice weevils, including the egg, larval (1st – 4th instars), pupal, and adult phases. Additionally, we examined post-treatment retention times of 0, 24, 48, and 72 h to assess how long the treated weevils survived after exposure. We observed that both treatment time and post-treatment retention time impacted, especially for weevils treated with shorter durations. Higher treatment times (5,8, and 10 min) showed that eggs failed to hatch, larvae and pupae were unable to emerge, and adults either died immediately after treatment (depending on the treatment duration) or within 24–48 h post-treatment. Based on these findings, we can conclude that ACP has detrimental effects on rice weevils, providing valuable insights into the potential use of ACP as an integrated pest management strategy.

Remodel the perifollicular microenvironment via Minoxidil-loaded microneedle patch and cold atmospheric plasma for treating androgenetic alopecia

Remodel the perifollicular microenvironment via Minoxidil-loaded microneedle patch and cold atmospheric plasma for treating androgenetic alopecia

Effect of (multi pin) atmospheric cold plasma treatment on curcumin extraction and investigating phytochemicals, antioxidants, physical and morphological properties of turmeric (Curcuma longa L.) powder

This investigation was focused on the impact of cold plasma (CP) on the extraction of curcumin and bioactive compounds of turmeric powder (TP). TP was treated with CP at different applied voltages (10, 20, and 30 kV), with various exposure times (10, 20, and 30 min). The curcumin content was highest at 30 kV for 10 min with a yield of 46.49 mg/g of TP. Total phenols significantly (p < 0.05) enhanced from 163.91 to 360.78 mg GAE/g DW accompanied by a remarkable 16% increment in total flavonoids, paralleled by a 26% increment in antioxidants as of control. Nuclear magnetic resonance spectra justified the extraction of curcuminoids. Moreover, micrographs displayed cell lysis in the treated powder. CP has exhibited a positive effect on surface colour parameters and thermal properties of TP. Overall, CP technology can be tailored for better curcumin extraction and the enhancement of phytochemicals.

Application of atmospheric cold plasma for zearalenone detoxification in cereals: Kinetics, mechanisms, and cytotoxicity analysis

IntroductionZearalenone (ZEN) is one of the most widely contaminated mycotoxins in world, posing a severe threat to human and animal health. Atmospheric cold plasma (ACP) holds great penitential in mycotoxin degradation. ObjectivesThis study aimed to investigate the degradation efficiency and mechanisms of ACP on ZEN as well as the cytotoxicity of ZEN degradation products by ACP. Additionally, this study also investigated the degradation efficiency of ACP on ZEN in cereals and its effect on cereal quality. MethodsThe degradation efficiency and products of ZEN by ACP was analyzed by HPLC and LC-MS/MS. The human normal liver cells and mice were employed to assess the cytotoxicity of ZEN degradation products. The ZEN artificially contaminated cereals were used to evaluate the feasibility of ACP detoxification in cereals. ResultsThe results showed that the degradation rate of ZEN was 96.18 % after 30-W ACP treatment for 180 s. The degradation rate was dependent on the discharge power, and treatment time and distance. Four major ZEN degradation products were produced after ACP treatment due to the oxidative destruction of CC double bond, namely C18H22O7 (m/z = 351.19), C18H22O8 (m/z = 367.14), C18H22O6 (m/z = 335.14), and C17H20O6 (m/z = 321.19). L02 cell viability was increased from 52.4 % to 99.76 % with ACP treatment time ranging from 0 to 180 s. Mice results showed significant recovery of body weight and depth of colonic crypts as well as mitigation of glomerular and liver damage. Additionally, ACP removed up to 50.55 % and 58.07 % of ZEN from wheat and corn. ConclusionsThis study demonstrates that ACP could efficiently degrade ZEN in cereals and its cytotoxicity was significantly reduced. Therefore, ACP is a promising effective method for ZEN detoxification in cereals to ensure human and animal health. Future study needs to develop large-scale ACP device with high degradation efficiency.

A large-scale cold plasma jet: generation mechanism and application effect

Atmospheric pressure cold plasma jets (APCPJs) typically exhibit a slender, conical structure, which imposes limitations on their application for surface modification due to the restricted treatment area. In this paper, we introduce a novel plasma jet morphology known as the large-scale cold plasma jet (LSCPJ), characterized by the presence of both a central conical plasma jet and a peripheral trumpet-like diffuse plasma jet. The experimental investigations have identified the factors influencing the conical and the trumpet-like diffuse plasma jet, and theoretical simulations have shed light on the role of the flow field and the electric field in shaping the formation of the LSCPJ. It is proved that, under conditions of elevated helium concentration, the distributions of impurity gas particles and the electric field jointly determine the plasma jet’s morphology. High-speed ICCD camera images confirm the dynamic behavior of plasma bullets in LSCPJ, which is consistent with the theoretical analysis. Finally, it is demonstrated that when applied to the surface treatment of silicone rubber, LSCPJ can achieve a treatment area over 28 times larger than that of APCPJ under equivalent conditions. This paper uncovers the crucial role of impurity gases and electric fields in shaping plasma jet morphology and opens up the possibility of efficiently diversifying plasma jet generation effects through external electromagnetic fields. These insights hold the promise of reducing the generation cost of plasma jets and expanding their applications across various industrial sectors.

The effect of dielectric barrier discharge plasma treatment on Dulcicalothrix alborzica (Nostocales, cyanobacteria) under lead stress

Cyanobacteria have shown considerable potential as effective adsorbents for the elimination of trace metals. Nevertheless, the precise adsorption mechanism of Dulcicalothrix alborzica remains uncertain. In this study, the activated water and biomass from Dulcicalothrix alborzica under dielectric barrier discharge plasma (DBD) treatment for lead removal were investigated at 5 (P5), 10 (P10), 15 (P15), and 20 (P20) minutes. Also, the FTIR and GC-MS analyses for identifying the functional groups and chemical composition of the heavy metal adsorption were performed. The results of lead removal in activated water and biomass under DBD treatment showed that the highest level of metal removal belonged to P20 and P15 at 90 min, respectively. The FTIR analysis showed that all three FTIR spectra of the control sample, activated water, and activated biomass with cold plasma, in terms of the intensity and the wave number, matched to a great extent. In addition, the GC-MS test showed that the 3-methylbutanal and 2-methylbutanal were the predominant volatile compounds detected across all experimental treatments. The general result showed that compared to activated biomass and water, activated water with atmospheric cold plasma had a greater ability to remove lead heavy metal (173.4 ± 1.77 g dry weight). Moreover, a longer time (P20) to let the reactive species work on the substance is recommended for future investigation. Further studies are necessary to improve the efficacy of heavy metal removal from liquid matrices, identify the suitable voltage and retention period, and distinguish the appropriate mechanism of metal removal from liquid matrices in order to stay safe from metal toxicity from consumption.

Pulsed voltage cold atmospheric plasma jet and gold nanoparticles enhance cytotoxic anticancer effect

Efficient and biologically safe mode of cold atmospheric plasma jet (CAPJ) is crucial for the development of CAPJ-based anticancer therapy. In the experiment and numerical simulations, by changing the pulse duration of a positive-pulsed (PP) voltage, we found the optimal CAPJ modes with a regular streamer propagation and a maximum discharge current at a temperature T< 42 ∘C. These CAPJs substantially suppressed the viability of cancer cells. To enhance a cytotoxic effect of CAPJ treatment, gold nanoparticles (NPs) were added to the cells before and after the CAPJ exposure. Combination of CAPJ, generated with the PP voltage, and gold NPs decreased the viability of NCI-H23 epithelial-like lung adenocarcinoma, A549 lung adenocarcinoma, BrCCh4e-134 breast adenocarcinoma and uMel1 uveal melanoma cells. Polyethylene glycol-modified NPs with attached fluorescent labels were used to visualize the uptake of NPs. We demonstrated that NPs efficiently entered the cells when were added to the cells just before CAPJ exposure or up to two hours afterwards. The efficiency of NPs penetration into cells positively correlated with the induced cytotoxic effect: it was maximal when NPs was added to cells right before or immediately after CAPJ exposure. Summarizing, the treatment with optimal CAPJ modes in combination with modified NPs, bearing the cancer-addressed molecules and therapeutics may be the next strategy of strengthening the CAPJ-based antitumor approaches.

Assessing the Effects of Cold Atmospheric Plasma on the Natural Microbiota and Quality of Pork during Storage.

Cold atmospheric plasma (CAP) is a novel non-thermal technology with significant potential for use in meat processing to prolong shelf life. The objective of the study was to evaluate the efficiency of CAP treatment on the natural microbiota and quality traits of pork stored for 8 days at 4 °C. CAP treatment was applied by employing piezoelectric direct discharge technology to treat pork samples for 0, 3, 6, and 9 min. Reductions of approximately 0.8-1.7 log CFU/g were observed in total viable counts (TVC) and Pseudomonas spp. levels for CAP treatments longer than 3 min, immediately after treatment. A storage study revealed that CAP-treated pork (>6 min) had significantly lower levels of TVC, Pseudomonas spp., and Enterobacteriaceae throughout storage. Regarding quality traits, CAP application for longer than 3 min significantly increased water retention and yellowness and decreased meat redness compared to untreated pork. However, other parameters such as pH, tenderness, and lightness exhibited no statistically significant differences between untreated and CAP-treated pork. Lipid oxidation levels were higher only for the 9-min treatment compared to untreated pork. Our results revealed that CAP is a promising technology that can extend the microbiological shelf life of pork during refrigeration storage.

Impact of open‐air processing on atmospheric pressure plasma deposition of poly(ethylene oxide) coatings for antifouling applications

AbstractAtmospheric pressure plasma deposition (APPD) of poly(ethylene oxide) (PEO)‐like antifouling coatings provides an attractive way to reduce biofouling for reliable biosensor operation. Cold atmospheric pressure plasma jets are designed to operate in open air. This paper demonstrates the impact of open‐air processing on the composition and properties of PEO‐like coatings by APPD with vinyl ether precursors. The open‐air environment inhibits polymerization as indicated by low deposition rates, oxygen incorporation in the coatings, and instability of the coatings in water. The composition and stability of the coatings improve by appropriate nozzle design and by deposition in an environment with lower air content. The resulting PEO‐like coatings are stable and antifouling for an antibody solution and inhibit adhesion of human fibroblast cells.

Pathogens inactivation and preservation of Pacific white shrimp by atmospheric cold plasma treatment

Atmospheric cold plasma (ACP) efficacy in inactivating Listeria monocytogenes and Vibrio parahaemolyticus was investigated on fresh and frozen shrimp. ACP inactivation efficacy increased with treatment time (5–20 min) and treatment voltages (60–80 kV) due to increased reactive gas species. ACP yielded stronger pathogen inactivation on frozen versus fresh shrimp. ACP treatment at 80 kV for 30 min maximally reduced L. monocytogenes and V. parahaemolyticus by 0.94 and 1.26 log CFU/g on fresh shrimp and by 1.68 and 2.0 log CFU/g on frozen shrimp. During storage at 4 °C, ACP-treated shrimp exhibited slightly higher thiobarbituric acid reactive substances (TBARS) levels but overall improved quality attributes, including lower total viable count, total volatile basic nitrogen, and pH, as well as higher sensory scores compared to the controls. ACP also extended shrimp shelf-life by 2 days. Therefore, ACP holds significant potential for seafood disinfection and preservation. Industrial relevanceACP effectively reduced levels of Listeria monocytogenes and Vibrio parahaemolyticus on both fresh and frozen shrimp with greater inactivation effects on frozen shrimp. In addition to enhancing microbial safety, ACP also improved shrimp quality and extended shelf-life. ACP could readily be coupled with packaging technology and bio preservatives to enhance its efficacy. This research provides a foundation for the eventual industrial adoption of ACP technology to benefit both consumers through reduced pathogen risks, and seafood processors through improved product safety, quality, and shelf-life.