Low-temperature Plasma Treatment Research Articles

Surface-dependent quenching of Qdot emission can be a new tool for high resolution measurements

Single quantum dots (Qdots) are often used in the field of single-molecule imaging. Qdots are sensitive to changes in the physical interactions between the Qdots and the surrounding materials. However, the spectral changes in a single Qdot emission have not been studied in detail. Low-temperature plasma treatment of glass surfaces reduced the intensity of the 655 nm emission peak of Qdot655 on glass surfaces, but did not significantly change the intensity of the 580 nm emission. Silanization of the glass surface increases the thickness of the silane layer, and the 655 nm emission peak increased. When single Qdots on the untreated glass were imaged, plasma treatment decreased the intensity of red emission and increased yellow emission. When Qdots were brought close to the glass surface in the range of 28–0 nm, the red emission intensity decreased and the yellow emission intensity increased slightly. When single actin filaments were labeled with Qdots, fluctuations of the yellow and red emission of the Qdot were detected, which reflected the very small distance changes. Our results indicate that the local interaction of Qdots with the glass surface improves the spatial and temporal resolution of optical measurements of biomolecules labeled with Qdots.

Effect of low-temperature plasma treatment on electrophysical and physical-mechanical properties of CVD coatings of carbide plates

The results of the study of the influence of regime parameters of the process of low-temperature plasma treatment on the electrical and physical-mechanical properties of CVD coatings of replaceable multifaceted hard-alloy plates are presented.

Design of Non-Thermal Plasma Alfalfa Seed Vigor Enhancement Device and Study of Treatment Effect

Highlights An effective seed treatment method is provided. Three generations of field growth trials were conducted. We Investigated the effects of low-temperature plasma treatment on the biological characters and yield components. Abstract. An atmospheric pressure, low-temperature dielectric barrier discharge (DBD) plasma seed treatment device was developed for plasma seed treatment. The device worked continuously on alfalfa seeds and evenly distributed the seeds in a plasma discharge range. The processing time, voltage amplitude, and frequency were adjustable. The device was used to study the effect of DBD plasma treatment at different voltages and times on alfalfa seed germination using untreated alfalfa seeds as the control (CK). The results showed that the DBD plasma treatment of alfalfa seeds promoted seed germination and seedling growth, and the optimal discharge conditions were a discharge voltage of 11 kV and a discharge time of 40 s. Compared with CK, the germination potential and germination rate increased by 12.49% and 18.08%, respectively. After treatment using the optimal discharge time, the germination potential, germination rate, dry weight, and seedling height increased by 9.9%, 16.1%, 15%, and 32.9%, respectively, compared with CK. The Scanning Electron Microscope images of the seed epidermis treated with 11 kV and 40 s plasma showed that the surface of alfalfa seeds was etched. Different doses of discharge radiation had different effects on physiological processes in seeds, and their sensitivity to plasma discharge was different. In a certain range, the germination rate, germination potential, fresh weight, dry weight, root length, and seedling height of alfalfa seeds improved to different degrees under different discharge voltages and times. Plasma has a good application prospect for improving the growth of alfalfa seeds. Keywords: Alfalfa, Dielectric barrier discharge plasma, Germination, Seed treatment device, Seedling growth.

Impact of low-temperature plasma treatment on electrical properties of CVD coatings of carbide plates

The paper presents the results of studying the influence of morphology and elemental composition, changed by the action of low-temperature plasma, on the electrical properties of CVD coatings of replaceable polyhedral carbide plates.

Effect of Low-Temperature Plasma Treatment on The Properties of a Complex Wool-Containing Material

The article investigates a layer of felt in a complex material, which we intend as rehabilitation footwear element. The complex material consists of layers of rubber and felt, connected with polyurethane adhesive, and we design it for the manufacture of shoe-product sole. The layer of felt inside is in contact with the foot and serves as an insole. The felt was treated with low-temperature plasma (LTP) from the inside of the complex material. It was experimentally obtained the wettability index: for the complex material, containing a treated layer of felt, and a control untreated felt. The research obtained an increase in the hydrophilicity of the LTP-treated felt, which is explained by degreasing the surface, an increase in the porosity of the non-woven material «felt», as well as structural changes in the wool fiber due to plasma treatment. Plasma treatment of woolen felt layer can be recommended to increase the hydrophilicity of the surface and impart antibacterial properties to the inner («insole») surface of the complex material by applying infusions of medicinal plants, etc.

The Effects of Storage Temperature, Light Illumination, and Low-Temperature Plasma on Fruit Rot and Change in Quality of Postharvest Gannan Navel Oranges.

Gannan navel orange (Citrus sinensis Osbeck cv. Newhall) is an economically important fruit, but postharvest loss occurs easily during storage. In this study, the effects of different temperatures, light illuminations, and low-temperature plasma treatments on the water loss and quality of the Gannan navel orange were investigated. The fruit began to rot after 90 d of storage at 5 °C and 20-45 d at 26 °C. Navel oranges stored at 26 °C had 7.2-fold and 3.1-fold higher rates of water loss at the early and late storage stages, respectively, as compared with those stored at 5 °C. Storage at 5 °C decreased the contents of total soluble solids at the early storage stage and the contents of titratable acids at the late storage stage, whereas storage at 26 °C decreased the contents of total soluble solids at the late storage stage and the contents of titratable acids at the early storage stage, respectively. Application of low-temperature plasma produced by air ionization for 6 min, or continuous blue or red light illumination significantly inhibited water loss within 7 and 21 d of storage at 22 °C, respectively, but exhibited no significant effect on fruit quality. Furthermore, the low-temperature plasma treatment protected against fruit rot. Thus, treatment with low-temperature plasma followed by storage at a low temperature under continuous red or blue light illumination was of potential value as a green technology for preserving Gannan navel orange during storage.

Morphology of Biomaterials Affect O-Glycosylation of HUVECs.

Biomaterials have been widely used as substitutes for diseased tissue in surgery and have gained great success and attention. At present, the biocompatibility of biomaterials such as PET woven fabrics is often evaluated both in vitro and in vivo. However, the current experimental methods cannot reveal the relationship between material surfaces and cell adhesion, and few research works have focused on the mechanisms of how the surface morphology of biomaterials affects cell adhesion and proliferation. Thus, it is meaningful to find out how the altered surfaces could affect cell adhesion and growth. In this study, we employed Ar low-temperature plasma treatment technology to create nano-grooves on the warp yarn of PET woven fabrics and seeded human umbellar vein endothelial cells (HUVEC) on these fabrics. We then assessed the O-glycan and N-glycan profiles of the cells grown on different structures of the polyester woven fabrics. The result showed that the surface morphology of polyester woven fabrics could affect the O-glycan profile but not the N-glycan profile of cultured HUVEC. Taken together, the study describes the effects of the surface morphology of biomaterial on the biosynthesis of cellular glycans and may provide new insights into the design and manufacture of biomaterials used as blood vessels based on the expression profiles of O-glycans on cultured cells.

Development and properties of active films based on potato starch modified by low-temperature plasma and enriched with cinnamon essential oil coated with nanoparticles

Potato starch dispersion was modified with low-temperature plasma (LTP) and cinnamon essential oil (CEO) was successfully loaded into mesoporous nano-silica particles (SBA-15). The SBA-15-CEO/LTP-potato starch film was prepared to explore the effects of LTP and SBA-15-CEO on the thermal stability, mechanical and physical properties of the starch-based film. The results showed that the plasma modification and SBA-15-CEO improved the thermal stability and mechanical and physical properties, as well as reduced the gas permeability of the film. Significantly, the crystal structure of the LTP- potato starch film changed after adding SBA-15-CEO. The optimized SBA-15-CEO/LTP-potato starch film (1.5 g glycerin; 0.5 g SBA-15-CEO) had the best mechanical properties and thermal stability and the lowest air permeability and hydrophilicity. Moreover, the aggregation of SBA-15-CEO decreased after LTP treatment, and the appearance of irregular and rough fractured surfaces was also alleviated. After LTP modification, the agglomeration of SBA-15-CEO in the film was solved to some extent. The addition of SBA-15-CEO alleviated the problem of starch dehydration and film cracking caused by LTP modification. Therefore, LTP is a simple and environmentally friendly method to improve the properties of potato starch film.

Effects of low-temperature plasma modification on properties of CEO-SBA-15/potato starch film

A potato starch solution was modified by low-temperature plasma (LTP), and cinnamon essential oil (CEO) was incorporated with mesoporous silica nanoparticles (SBA-15) to obtain modified CEO-SBA-15/potato starch film. The mechanical properties, physical properties and gas resistance properties of the films were measured when the LTP treatment time was 0 min, 3 min, 6 min, 9 min, 12 min and 15 min. LTP treatment significantly increased the tensile strength and elongation at break of the material, and decreased the air permeability and hygroscopicity, until LTP treatment time was 9 min. The SEM results showed that circular cracks appeared on the surface of the potato starch granules after the plasma treatment. Notably, the number of circular cracks increased as the processing time increased. This may be beneficial to the effect of LTP on starch internal structure. The film had the optimal water vapor transmittance rate (12.05 g/(m2·h)), opacity (3.15%), tensile strength (3.55 MPa), and oxygen transmittance rate (5.129 × 10−15 cm2 s−1 Pa−1) at a treatment time of 6 min. Significantly, the LTP-modified potato starch improved the performance of film and reduced the aggregation of nanoparticles in the film.

Growth Enhancement of Radish Seed Induced by Low-Temperature Argon Plasma

The process of seed germination is described as the culmination of a series of events that start with wetting and end with the emergence of the embryo (typically the radicle) from the seed coat. This method has an impact on crop output and quality. The characteristics of the seed surface and the surroundings have an impact on the kinetics and volume of water absorption by seeds. As a result, modifying the characteristics of a seed's surface is a useful tactic for influencing seed germination. Low-temperature plasma (LTP) treatment of the seed for surface activation is now being researched as an effective pre-sowing technique. This study looked at the effects of LTP on radish (Raphanus sativus) seeds at room temperature for various times. The seed's germination properties, growth parameters, water contact angle (WCA), Scanning Electron Micrograph (SEM), and FTIR analysis were examined. WCA and SEM examination revealed a considerable alteration in the seed coat following LTP treatment, which is directly connected to water permeability into the seeds. Similarly, FTIR analysis confirmed that the enhancement of the hydrophilic properties of the seeds following plasma treatment is likely due to the damage of the hydrophobic moieties on the seeds' surface. The LTP treatment improved each germination-related parameter, including the vigor index, chlorophyll content, in-vitro radical scavenging activities, total flavonoid, and phenol in the seedlings. Our findings indicate that LTP treatment has a beneficial impact on early seed sprouting and the development of radish.

Low-Temperature Plasma Short Exposure to Decontaminate Peri-Implantitis-Related Multispecies Biofilms on Titanium Surfaces In Vitro.

The use of low-temperature plasma (LTP) is a novel approach to treating peri-implantitis. LTP disrupts the biofilm while conditioning the surrounding host environment for bone growth around the infected implant. The main objective of this study was to evaluate the antimicrobial properties of LTP on newly formed (24 h), intermediate (3 days), and mature (7 days) peri-implant-related biofilms formed on titanium surfaces. Actinomyces naeslundii (ATCC 12104), Porphyromonas gingivalis (W83), Streptococcus oralis (ATCC 35037), and Veillonella dispar (ATCC 17748) were cultivated in brain heart infusion supplemented with 1% yeast extract, hemin (0.5 mg/mL), and menadione (5 mg/mL) and kept at 37°C in anaerobic conditions for 24 h. Species were mixed for a final concentration of ~105 colony forming units (CFU)/mL (OD = 0.01), and the bacterial suspension was put in contact with titanium specimens (7.5 mm in diameter by 2 mm in thickness) for biofilm formation. Biofilms were treated with LTP for 1, 3, and 5 min at 3 or 10 mm from plasma tip to sample. Controls were those having no treatment (negative control, NC) and argon flow under the same LTP conditions. Positive controls were those treated with 14 μg/mL amoxicillin and 140 μg/mL metronidazole individually or combined and 0.12% chlorhexidine (n = 6 per group). Biofilms were evaluated by CFU, confocal laser scanning microscopy (CLSM), and fluorescence in situ hybridization (FISH). Comparisons among bacteria; 24 h, 3-day, and 7-day biofilms; and treatments for each biofilm were made. Wilcoxon signed-rank and Wilcoxon rank sum tests were applied (α = 0.05). Bacterial growth was observed in all NC groups, corroborated by FISH. LTP treatment significantly reduced all bacteria species compared to the NC in all biofilm periods and treatment conditions (p ≤ 0.016), and CLSM corroborated these results. Within the limitation of this study, we conclude that LTP application effectively reduces peri-implantitis-related multispecies biofilms on titanium surfaces in vitro.

Effect of Low-Temperature Plasma Treatment on Starch-Based Biochar and Its Reinforcement for Three-Dimensional Printed Polypropylene Biocomposites.

Uniform dispersion and high interfacial adhesion are two of the most difficult components of creating an ideally reinforced polymer composite. One of the solutions could be surface engineering of reinforcing filler materials utilizing innovative technologies. Low-temperature plasma treatments in the presence of sulfur hexafluoride (SF6) gas are proposed as a sustainable alternative to modify the surface properties of biochar carbon synthesized from sustainable starch-based packaging waste via a high-temperature/pressure pyrolysis reaction in the current study. X-ray photoelectron spectroscopy tests revealed that plasma treatments were effective in the fluorination of biochar carbon like wet chemical methods. By delivering fluorine-related functionalities only on the surface of the carbon, plasma treatments were efficient in changing the surface properties of biochar carbon while keeping the carbon's beneficial bulk properties intact, which is unique to this method. The modified biochar was effectively utilized to reinforce polypropylene. Mechanical properties like tensile strength improved by 91% when compared to neat polymers and 31% when compared to untreated biochar-reinforced polymers at 0.75 wt % loadings. Elongation at break increased from 12.7 to 38.78, showing an impressive 216% increase due to effective reinforcement by plasma functionalization. The decomposition onset temperature and maximum rate of decomposition temperature increased by 60 and 49 °C, respectively, when compared to neat polymers. Plasma-modified biochar-reinforced three-dimensional printed samples have shown promise to be utilized for the development of composite parts using additive manufacturing methods.

Surface Modification on Polyimide Yarn by Plasma Treatment to Enhance Adhesion with Polypropylene Resin.

Polyimide yarn as a kind of high performance fiber material has to improve the adhesion between the material surface and the resin in order to get a deeper application. The surface of polyimide yarn is modified by low temperature plasma treatment, and the effect of plasma treatment parameters on the adhesion between polyimide yarn and polypropylene resin is studied. By comparing the extraction force on the surface of polyimide yarn before and after treatment, the effect of plasma treatment parameters such as treatment time, processing gas and treating power on yarn adhesion is investigated. Furthermore, the adhesive force between polyimide yarn and polypropylene resin is analyzed by a single factor to optimize the process parameters to obtain higher adhesive force. Additionally, the Box–Behnken design is utilized to optimize the plasma treatment parameters, and the significance of the influence of the plasma treatment parameters on the adhesion between the polyimide fiber and the resin is discussed. The optimal process parameters are obtained through analysis: the treatment time 90 s, the processing gas oxygen, and the treating power 150 W.

Excellent Adhesive Performance for the Thermal Insulation Attribute to Micromorphology Regulation and Controllable Injection of Oxygen‐Containing Groups by Low Temperature Plasma Treatment

AbstractA low temperature plasma (LTP) surface treatment technology operated under atmospheric conditions with air as the treatment atmosphere is developed for micromorphology regulation and controllable injection of oxygen‐containing groups on the surface of ethylene propylene diene methylene (EPDM) thermal insulation to achieve excellent adhesion performance. Optical emission spectroscopy is used to analyze the active species in the LTP. The key treatment parameters are optimized by contact angle measurements, resulting in thermal insulation sample with 3.32 times higher surface energy than the original sample. The surface morphology and composition of the samples are characterized. It is demonstrated that the surface of the thermal insulation shows new structures, thus increasing the surface area of the thermal insulation. In addition, a large number of oxygen‐containing groups are introduced to the surface of the thermal insulation, especially OH, and the O/C increases by 78.57%. Finally, the peel test is performed on the insulation samples with comparison to the grinding samples, which shows that the peel strength of the treated samples increases by 126.92%, while an additional 22% is also obtained compared to the grinding samples. This excellent adhesive performance is mainly caused by the synergistic effect of chemical crosslinking, hydrogen bonding, and mechanical interlocking.

Low Temperature Plasma Suppresses Lung Cancer Cells Growth via VEGF/VEGFR2/RAS/ERK Axis.

Low temperature plasma (LTP) is a promising cancer therapy in clinical practice. In this study, dielectric barrier discharge plasma with helium gas was used to generate LTP. Significant increases in extracellular and intracellular reactive species were found in lung cancer cells (CALU-1 and SPC-A1) after LTP treatments. Cells viability and apoptosis assays demonstrated that LTP inhibited cells viability and induced cells death, respectively. Moreover, Western blotting revealed that the growth of CALU-1 cells was suppressed by LTP via the VEGF/VEGFR2/RAS/ERK axis for the first time. The results showed that LTP-induced ROS and RNS could inhibit the growth of lung cancer cells via VEGF/VEGFR2/RAS/ERK axis. These findings advance our understanding of the inhibitory mechanism of LTP on lung cancer and will facilitate its clinical application.

Effect of low‐temperature plasma treatment on the microbial inactivation and physicochemical properties of the oat grain

AbstractBackground and ObjectivesNaked oat grain is easily contaminated by microorganisms, and it needs pretreatment to extend its shelf life. Low‐temperature plasma treatment (LTPT) has the advantages of less energy consumption, safety, and convenience, and its applications in grain include microbial inactivation and flour modification. Therefore, we studied the changes in oat microbes and the physicochemical properties of oats at different plasma treatment times (0, 5, 10, 15, and 20 min at an output discharge voltage of 60 kV).FindingsThe results demonstrated that LTPT significantly decreased the number of microorganisms with the increase in treatment time, especially at 20 min. LTPT increased the L* and b* values and decreased the a* value of oat flour. Proper treatment time (5–10 min) did not affect the germination rate of the grain. Compared to the control sample, LTPT increased the water‐binding capacity and swelling power of flour and decreased the peak viscosity, final viscosity, and setback value. However, LTPT did not change the crystal structure. Besides, by fitting the peak of the amide region in Fourier transfer infrared analysis, it was found that the β‐sheet and α‐helix increased after treatment for 5–10 min.ConclusionsThese results indicated that LTPT (20 min) can effectively reduce the microbial count of oats and proper time treatment (5–10 min) can regulate the function of the flour and improve its quality.Significance and NoveltyLTPT as a new nonheat treatment technology can not only effectively reduce the microbial content of the grain but also improve the quality of the flour, which is a better pretreatment method for oat flour.

Low-Temperature Barrier Discharge Plasma Modification of Scaffolds Based on Polylactic Acid.

We have explored the effect of low-temperature barrier discharge plasma treatment in oxygen, nitrogen, and argon on modification of the physicochemical properties of polylactic acid (PLA)-based scaffolds. The cellular-mediated immune response to the interaction of macrophages of three donors with the modified surface of PLA-based scaffolds was also investigated. Carbonization of the PLA surface accompanied by a carbon atomic concentration increase is shown to occur following plasma treatment. Argon plasma significantly affects the wettability characteristics of PLA; the hydrophilicity and lipophilicity are improved, and the surface energy is increased. The viability of cells in the presence of plasma-modified PLA scaffolds is lower than that for unmodified PLA but remains greater than that for the negative control. We find that PLA scaffolds do not cause increased expression of the proinflammatory (TNFα, IL-6, IL-1β) cytokines after 6 days of cell cultivation. At the same time, PLA scaffolds do not affect the increased production of anti-inflammatory cytokines (IL-10).

Critical Salt Loading in Flexible Poly(vinyl alcohol) Sensors Fabricated by an Inkjet Printing and Plasma Reduction Method.

We report a low-temperature inkjet printing and plasma treatment method using silver nitrate ink that allows the fabrication of conductive silver traces on poly(vinyl alcohol) (PVA) film with good fidelity and without degrading the polymer substrate. In doing so, we also identify a critical salt loading in the film that is necessary to prevent the polymer from reacting with the silver nitrate-based ink, which improves the resolution of the silver trace while simultaneously lowering its sheet resistance. Silver lines printed on PVA film using this method have sheet resistances of around 0.2 Ω/□ under wet/dry and stretched/unstretched conditions, while PVA films without prior treatment double in sheet resistance upon wetting or stretching the substrate. This low resistance of printed lines on salt-treated films can be preserved under multiple bending cycles of 0–90° and stretching cycles of 0–6% strain if the polymer is prestretched prior to inkjet printing.

Improvement of photocatalytic activity of BiOBr and BiOBr/ZnO under visible-light irradiation by short-time low temperature plasma treatment

In this work, BiOBr and BiOBr/ZnO were produced by using a simple hydrothermal method, and then were modified by a short-time low temperature plasma treatment using the gas of argon mixed with 3% hydrogen in pulsed mode with the fixed cycle discharge times. The related morphological, crystal, chemical, optical and photocatalytic properties were investigated. A three-dimensional flower-like structure of pure BiOBr and layered ultrathin nanosheets structure of BiOBr/ZnO can be observed. And the plasma treatment process at the discharge power of 100 W would not affect their basic morphologies. However, the changes in the surface chemical bonding has been identified, which indicates the presence of strong electronic interactions and strong chemical bonds caused by the plasma modification. The photodegradation rate has been greatly improved by mixing BiOBr with ZnO since the heterojunction structure was built during the hydrothermal process. Moreover, the photocatalytic activity can be further improved after the plasma treatment, it is attributed to the higher photogenerated carrier separation rate and narrow band gap due to the defects generated by the surface plasma effects.

Stab-resistance improvement of short carbon fiber reinforced UHMWPE knitted composites with plasma/oxidation treatment

Two modification methods, including low temperature plasma treatment and HNO3 oxidation, used to modify double-layer knitted fabric (DLKF) with UHMWPE yarn and CFs respectively. Contact angle, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) are used to evaluate the modification effect of the fabric or CFs. Epoxy resin (ER) is used as adhesive to prepare composite, and the effect of modification on the stab resistance is further studied through the test of stab resistance. In addition, the damage mechanism of DLKF and R-DLKF are analyzed. The results showed that the plasma treatment has a great effect on the modification of DLKF. After 15–20min of modification, the stab resistance of the composite is the best. The peak load and energy can be increased by about 19.1% and 23.1%. HNO3 oxidation has a great effect on the modification of CFs, the stab-resistance of CFs reinforced DLKF (R-DLKF) can be improved by about 17.3% after being treated with 60% HNO3 for 24h. DLKF fails mainly due to the stretching and cutting action of the yarn. Fabric as matrix can prevent crack propagation further, and the shear force, yarn cutting and pullout action within the composite is the key to improve the stab resistance. This work opens up the possibilities for the industrial production of personal protection products and devices, which is expected to provides a reference for the modification of fabrics and fibers in the production of composite.