Cold Atmospheric Pressure Plasma Jet Research Articles

Mechanism of lipid peroxidation of liposomes by cold atmospheric pressure plasma jet irradiation

Mechanism of lipid peroxidation of liposomes by cold atmospheric pressure plasma jet irradiation

Investigation of the effects of atmospheric pressure cold plasma on bacterial isolates

Background: Atmospheric pressure cold plasma is a type of non-thermal plasma used for antimicrobial activity in the health, food and agriculture sectors. This study was carried out to investigate the efficacy of atmospheric pressure cold plasma on different bacterial isolates. Materials and Methods: The study was conducted on standard reference bacterial strains; Escherichia coli (O157:H7), Bacillus subtilis (ATCC 6633), Enterobacter aerogenes (ATCC 13048), Rhodococcus equi (ATCC 6939), Salmonella typhimurium (ATCC 14028), Enterococcus feacalis (ATCC 2912) and field isolates; 12 Escherichia coli isolates, 22 Staphylococcus spp, 18 Klebsiella spp., 2 Enterococcus spp., 3 Acinetobacter spp., 8 Candida spp., 1 Morgarella mongarii, 2 Corynebacterium spp., 1 Streptococcus pyogenes. Atmospheric pressure cold plasma jet and plasma activated medium (PAM) were applied to the isolates and their efficacy was investigated. Results: As a result of the study, it was found that cold plasma was effective against Escherichia coli (O157:H7), Enterobacter aerogenes (ATCC 13048), Salmonella typhimurium, Rhodococcus equi (ATCC 6939) and Enterococcus feacalis (ATCC 2912) among standard bacterial strains, while it was effective against Streptococcus pyogenes (group A Bet) and Staphylococcus epidermidis among field isolates. Conclusions: As a result of our study, the antimicrobial activity of atmospheric pressure cold plasma and PAM was demonstrated, and we believe that it will contribute to the health, food and agriculture sectors.

Development of cold atmospheric pressure plasma jet sources for biomedical application

Development of cold atmospheric pressure plasma jet sources for biomedical application

Effect of Atmospheric Pressure Plasma Jet Treatments on Magnesium Phosphate Cements: Performance, Characterization, and Applications.

Atmospheric pressure plasma treatments are nowadays gaining importance to improve the performance of biomaterials in the orthopedic field. Among those, magnesium phosphate-based cements (MPCs) have recently shown attractive features as bone repair materials. The effect of plasma treatments on such cements, which has not been investigated so far, could represent an innovative strategy to modify MPCs' physicochemical properties and to tune their interaction with cells. MPCs were prepared and treated for 5, 7.5, and 10 min with a cold atmospheric pressure plasma jet. The reactive nitrogen and oxygen species formed during the treatment were characterized. The surfaces of MPCs were studied in terms of the phase composition, morphology, and topography. After a preliminary test in simulated body fluid, the proliferation, adhesion, and osteogenic differentiation of human mesenchymal cells on MPCs were assessed. Plasma treatments induce modifications in the relative amounts of struvite, newberyite, and farringtonite on the surfaces on MPCs in a time-dependent fashion. Nonetheless, all investigated scaffolds show a good biocompatibility and cell adhesion, also supporting osteogenic differentiation of mesenchymal cells.

Reactive species variation in cold atmospheric pressure plasma jet discharge under the influence of intrinsic parameters and its effect on E. coli inactivation.

Cold atmospheric pressure plasma jet (CAPJ) has piqued the interest of researchers for various antimicrobial applications such as disinfection, wound decontamination, etc. In the current context, a deeper understanding of the correlation between CAPJ's intrinsic parameters, discharge characteristics, species composition, and antimicrobial activity is required for any successful application. This research evaluated the effect of intrinsic operational parameters such as voltage, frequency, gas flow rate, and operating gas on the reactive species composition of an in-house-developed CAPJ discharge along with the antimicrobial activity. It was observed that the identified excited atoms (Ar I, He I, N2, and O I), ions (Ar+, N2+, N+, H2O+, H3O+, etc.), radical reactive oxygen and nitrogen species (RONS) (OH•), and nonradical RONS (O I, O+, OH+, NO+, O2+, O2-, NO2-, N2O2-, NO3-, N2O3-, etc.) might play a synergistic role in bacterial inactivation via oxidative and electrostatic stress. The variation in voltage, frequency, gas flow rate, and operating gas influenced the discharge chemistry, leading to variation in bacterial inactivation. The reactive species in the discharge responsible for such variation was evaluated extensively. This investigation into various operational parameters would aid in determining the most effective settings for a developed CAPJ to achieve high productivity.

Potentialities and limitations of an electro-optic probe for electric field diagnostics of cold atmospheric pressure plasma jets

Potentialities and limitations of an electro-optic probe for electric field diagnostics of cold atmospheric pressure plasma jets

Comparison of smear layer removing efficacy of Cold Atmospheric Pressure (CAP) Plasma Jet with different chelating agents. An ex-vivo study

The present study aimed to assess the effectiveness of different final irrigation regimens (Cold Atmospheric Pressure Plasma Jet, MTAD, and EDTA) in removing the smear layer from intra-radicular dentin using a Scanning Electron Microscope (SEM). Eighty-four mandibular premolars were prepared with ProTaper Universal hand files and were equally divided into four groups i.e. Normal saline (control), EDTA, MTAD and CAP Plasma Jet. Prepared samples in the control, EDTA and MTAD groups were irrigated with 5 milliliters of the irrigant, and it was retained for 2 min. In the CAP Plasma Jet group, the plasma plume was directed towards the canal lumen for 2 min. The smear layer removal of all the groups was evaluated at the coronal, middle and apical thirds. Statistical analysis was performed using Kruskal–Wallis test followed by Dunn’s test. Evaluation by SEM showed that the smear layer removal ability of MTAD and EDTA were significantly better than CAP Plasma Jet (p < 0.05). While CAP Plasma Jet showed results comparable to EDTA in the coronal third. In the middle and apical third of the canal, its effect was comparable to the control group (p > 0.05). MTAD and EDTA aided in better smear layer removal than the CAP Plasma Jet in the coronal, middle, and apical third of the test samples. CAP Plasma jet performed better in the coronal third.

Energetics of reactions in an atmospheric pressure plasma jet with argon carrier gas and hexamethyldisiloxane reagent

AbstractWe report on a methodology for measuring the energy dissipated per AC high voltage cycle in a cold atmospheric pressure plasma jet (CAPJet). This method is adapted from research by Nisol et al. on plasma polymerization of hexamethyldisiloxane (HMDSO) organosilicon vapor in a large area planar dielectric barrier discharge (DBD) reactor. Here too, we measured ΔEg, the energy difference with and without small HMDSO vapor concentrations in the argon carrier gas flow. From ΔEg we then derived Em, the energy per molecule, and compared values with those of Nisol. Good agreements were found, including in film structures determined from attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectra, thus suggesting that realistic Em values can be successfully obtained also for the CAPJet case.

Modification of chia (Salvia hispanica L.) seed mucilage (a heteropolysaccharide) by atmospheric pressure cold plasma jet treatment

Chia seeds (CS) were subjected to atmospheric pressure cold plasma jet (APCPJ) for different times (30, 60, and 120 s) by using argon gas, and then chia mucilage (CM) was extracted from the seeds to investigate the technological properties of mucilage (a heteropolysaccharide). The gel samples prepared from dried CM obtained from CS treated with 30 s and 120 s APCPJ showed noticeably higher consistency index of 11.43 and 13.63 Pa.sn, while the control and 60 s APCPJ showed a lower consistency index of 1.07 and 0.35, respectively. Herschel-Bulkley was better at defining the flow behavior of CM gels, and the treatment increased the shear-thinning and consistency properties. Moreover, CM gels of APCPJ-treated seeds (30 s and 120 s) showed higher elastic properties and better resistance against deformation. The treatment induced cross-linking between polysaccharide chains as confirmed by FTIR, and SEM micrographs demonstrated that APCPJ caused etching on the surface of seeds, thus a more compact structure was obtained in the hydrated mucilage samples depending on the APCPJ time. The highest treatment time (120 s) decreased the solubility, and the water (15%) and oil holding capacity (25%), while it did not significantly affect the emulsion ability and stability. In conclusion, it was found that the APCPJ improved the viscosity and elastic features of CM gels by cross-linking and strengthening the polymer network, which may provide opportunities to use this gum in new food applications.

Cold Atmospheric Pressure Plasma Jet and Plasma Lamp Interaction with Plants: Electrostimulation, Reactive Oxygen and Nitrogen Species, and Side Effects

Cold atmospheric pressure plasma (CAPP) treatment is a highly effective method of protecting seeds, plants, flowers, and trees from diseases and infection and significantly increasing crop yields. Here we found that cold atmospheric pressure He-plasma jet (CAPPJ) can also cause side effects and damage to plants if the plasma exposure time is too long. Reactive oxygen and nitrogen species (RONS), electromagnetic fields, and ultraviolet photons emitted by CAPPJ can cause both positive and negative effects on plants. CAPPJ can interact with biological tissue surfaces. The plasma lamp has no visible side effects on Aloe vera plants, cabbage, and tomatoes. A plasma lamp and a cold atmospheric pressure plasma He-jet cause strong electrical signaling in plants with a very high amplitude with frequencies equal to the frequency of plasma generation. The use of plasma lamps for electrostimulation of biological tissues can help to avoid side processes in biological tissues associated with the generation of RONS, UV photons, and direct interaction with cold plasma. CAPP technology can play an important role in agriculture, medicine, the food industry, chemistry, surface science, material science, and engineering applications without side effects if the plasma exposure is short enough.

Modification of Silicon Nanostructures by Cold Atmospheric Pressure Plasma Jets

Cold atmospheric plasma (CAP) jets with helium (He) and argon (Ar) plasma-forming gases were used to modify the structure, photoluminescence (PL), and electrical properties of arrays of silicon nanowires (SiNWs) with initial cross-section sizes of the order of 100 nm and length of about 7‒8 microns. The CAP source consisted of a 30 kHz voltage generator with a full power up to 5 W and the CAP treatment for 1‒5 min resulted in spattering of SiNWs’ tips followed by redeposition of silicon atoms. An increase of the silicon oxide phase and a decrease of the PL intensity were observed in the plasma processed SiNW arrays. A decrease of the free hole concentration and an increase in the free electron density were revealed in heavily boron and phosphorous doped SiNWs, respectively, as it was monitored by means of the Raman spectroscopy, considering a coupling of the light scattering by phonon and free charge carriers (Fano effect) in SiNWs. The obtained results demonstrate that the CAP treatment can be used to change the length, sharpness, luminescence intensity, and electrical properties of silicon nanowires for possible applications in optoelectronics and sensorics.

The localised density of H2O2 in the effluent of a cold atmospheric pressure plasma jet determined by continuous-wave cavity ring-down spectroscopy

Although the research on cold atmospheric pressure plasma jets and their applications is steadily growing, several questions remain open regarding fundamental aspects of how reactive species, such as hydrogen peroxide (H2O2), are generated in cold atmospheric pressure plasma jets, and how the composition of reactive species can be tailored for a specific purpose. Accordingly, absolute and spatially resolved distributions of the densities of reactive species in the effluent of cold atmospheric pressure plasma jets are required. In this work, a time efficient way to determine the local distribution of gas phase H2O2 in the effluent of a cold atmospheric-pressure plasma jet using continuous-wave cavity ring-down spectroscopy at a wavelength of 8.12 μm is presented. By a combination of an axial scan and of several radial distributions, the localised density distribution of H2O2 in the effluent of the kINPen-sci plasma jet was obtained. Therefore, the effective absorption length was determined from the evolution of the radial distributions as a function of the distance from the nozzle, which was 1.6 mm close to the nozzle of the plasma jet, and increased to approximately 5 mm at a distance of 10 mm from the nozzle. The maximum density of approximately 2 ⋅ 1014 cm−3 was found in the centre of the effluent close to the nozzle. From the presented localised density distribution, it can be concluded that H2O2 is significantly generated within the plasma zone of the plasma jet. This work presents an important step towards the understanding of formation and consumption mechanisms of biomedically relevant species in the plasma zone and the effluent of a cold atmospheric pressure plasma jet.

Molecular Modification of Zeolites with Cold Atmospheric-Pressure Plasma Jet: A Green and Facile Strategy

Widespread applications of zeolites demand the optimization of crystal size and morphology. Crystal growth modifiers (CGMs) have been proved effective for zeolite rational design, but the additional chemicals raise environmental and safety concerns. Herein, the industry-ready technique of cold atmospheric-pressure plasma jet (CAPPJ) was employed to induce reactive plasma species as green and eco-friendly CGMs. The synthesis mixtures of three aluminosilicate zeolites with assorted Si/Al ratios (SAR), channel dimensionalities, and pore apertures (i.e., MFI, LTA, and LTL framework types) were first subjected to Ar-CAPPJ treatment for up to 30 min during the aging period. Apparent size and shape modifications were successfully achieved for the resulting crystals with the emergence of rounded surfaces implying surface roughening at the molecular level. For the silicoaluminophosphate SAPO-34 (CHA type), the introduction of plasma CGMs was found to propel a phase transformation, promoting the crystallization of SAPO-18 (AEI type) impurity with reduced framework density. Experimental observations seem to suggest that the classical model of CGMs attaching to selected crystal surfaces is less likely to happen. Whereas, the investigation of zeolite L dispersions revealed enhanced concentrations and altered physicochemical properties of soluble species and amorphous precursors, alluding to the potential functional mechanism (s) of plasma CGMs. As a plausible technique to generate green and versatile CGMs, the impacts of CAPPJ on zeolite crystallization are systematically investigated for the first time, promoting the understanding of classical and nonclassical crystallization phenomena during zeolite synthesis.

An in-vitro analysis to evaluate the disinfection effectiveness of Cold Atmospheric Pressure (CAP) plasma jet in Enterococcus faecalis infected root canals

Cold Atmospheric Pressure (CAP) plasma has shown successful antibacterial efficacy in different medical applications which have prompted researchers to explore its possible use in endodontics. The aim of the present study was to comparatively evaluate the disinfection effectiveness of CAP Plasma jet with 5.25% sodium hypochlorite (NaOCl) and Qmix in Enterococcus Faecalis infected root canals at different time intervals (2, 5, and 10 min). 210 single-rooted mandibular premolars were chemomechanically prepared and infected with E. faecalis. The test samples were exposed to CAP Plasma jet, 5.25% NaOCl, and Qmix for 2, 5, and 10 min. The residual bacteria from the root canals if any were collected and evaluated for colony-forming units (CFUs) growth. ANOVA and Tukey’s tests were used to evaluate the significant difference between treatment groups. 5.25% NaOCl showed significantly more antibacterial effectiveness (<0.001) when compared with all other test groups except Qmix at 2 and 10 min of exposure time. A minimum contact time of 5 min with 5.25% NaOCl is recommended to get zero bacterial growth in E. faecalis infected root canals. QMix requires a minimum contact time of 10 min to achieve optimal CFUs reduction and CAP plasma jet requires a minimum contact time of 5 min to achieve substantial CFUs reduction.

On the gas heating effect of helium atmospheric pressure plasma jet

Plasma medicine is an emerging research field which has been driven by the development of plasma sources suitable to generate low temperature plasmas. In many cases, such devices can operate without a gas flow, producing a plasma discharge from the ambient air. However, the most common case is the use of a working gas at a given flow rate to produce a plasma jet. Helium (He) is one of the gases commonly used as the carrier gas to generate cold atmospheric pressure plasma jets (CAPPJs) due mainly to the easiness to ignite a gas discharge with it. However, in this work it was observed that most of the heating of a He CAPPJ can come just from the expansion of the He gas. This was found through measurements of gas temperature (T gas ), using fiber optic temperature (FOT) sensors, and thermal output, using both FOT and infrared imaging with the He flow impinging on a copper (Cu) plate. Such findings were achieved through comparisons of T gas and the temperature on the Cu (T Cu ) plate in the conditions with and without discharge ignition, as well as comparing T gas in the free gas/jet mode with and without discharge ignition. It was verified that the T gas values increased as the distance from the gas outlet was enlarged, especially at low He flow rates, even without discharge ignition. Despite the temperature increase with distance, it is possible to produce plasma jets with temperatures lower than 40 °C at low He flow rates.

Effect of Cold Atmospheric Pressure Argon Plasma Jet Treatment on the Freeze-Dried Mucilage of Chia Seeds (Salvia hispanica L.).

In the present study, the effects of the treatment of chia seeds with a cold atmospheric pressure plasma jet (CP) using argon as a working gas for different times (30, 60, and 120 s) on the rheological, structural, and microstructural properties of the freeze-dried mucilages at -54 °C were investigated. All mucilage gels showed pseudoplastic flow behavior, and CP treatment of chia seeds increased the viscosity of mucilages, probably due to the cross-linking between polymer molecules. The dynamic rheological analysis revealed that all mucilages were elastic gels and that CP treatment improved the elastic properties in a treatment time-dependent manner. Large amplitude oscillatory shear (LAOS) results showed that freeze-dried mucilages showed Type I strain-thinning behavior. Similar to small amplitude oscillatory shear (SAOS) results, CP treatment has affected and improved the large deformation behavior of mucilages depending on treatment time. Meanwhile, Fourier transform infrared spectroscopy (FTIR) revealed the incorporation of hydroxyl groups onto the surface and the formation of C-O-C glycosidic bonds during plasma treatment. Scanning electron microscope (SEM) micrographs showed the formation of denser structures with CP treatment time. Regarding color properties, CP treatment decreased the lightness values of mucilages. Overall, this study showed that CP is an effective way to modify both the SAOS and LAOS properties of freeze-dried chia mucilage and improve viscosity.

Spectroscopic investigation of atmospheric pressure cold plasma jet produced in dielectric barrier discharge

Non-thermal cold atmospheric pressure plasma jet (APPJ) produced in multi-pulse dielectric barrier discharge (DBD) preferentially heats the electrons that subsequently transfer their energy to the other plasma species converting them into reactive species. Therefore the characterization of different energy groups of electrons is essential for efficient production and control of reactive plasma species contributing to surface modifications. Here we present the spectroscopic investigations of the APPJ produced in multi-pulse DBD using pin electrode configuration. Boltzmann plot relates the emission intensities of the several Ar–I spectral lines to their corresponding threshold excitation energies to give the electron temperature more precisely. The Stark broadening of the Ar–I (696.54 nm) line profile gives the electron number density after de-convoluting the contributions of the Doppler and instrumental broadenings. Plasma measurements correlate the gas flow rate, applied jet power across the electrodes, and a group of electrons contributing to optical emission. Sequential imaging correlates the size of the plasma bullets momentarily with the discharge pulse for different argon flow rates and applied jet powers. With an increasing flow rate of up to 1.4 L/min, the plasma plume of the jet becomes more elongated, intense, and spatially uniform. However, the glow intensity and size of the plume start reducing with a further increase in gas flow rate. Experimental findings propose plasma processing for small-scale localized plasma surface treatments.

Synergistic Effect of Hydrogen Peroxide and Cold Atmospheric Pressure Plasma-Jet for Microbial Disinfection

The efficiency of simultaneous treatment of the cold atmospheric pressure plasma jet (CAP) and hydrogen peroxide (H2O2) was investigated. A CAP with a thin and long plume was generated with Ar gas and applied to a common oral bacterium, Enterococcus faecalis (E. faecalis). The bactericidal efficiency was evaluated with the electron microscopy and the colony forming unit (CFU) assay. The underlying mechanisms were studied by measuring extracellular chemical changes in the water solution and by measuring biological responses such as the trans-membrane potential, the intracellular oxidative stress, and the membrane permeability. The combination of CAP with H2O2 could provide dramatic synergistic effects in bacterial disinfection through the enhanced membrane transportation of reactive species and the oxidation of intracellular molecules. Since the byproducts of both H2O2 and CAP are not significantly toxic, the synergistic bactericidal effects of their combination could be a good candidate to clinical applications.

Study of increment of emission intensity in a cold atmospheric pressure helium plasma jet using the ADAS

In this paper, the Atomic Data and Analysis Structure (ADAS) has been used to study the cold atmospheric pressure plasma jet. Variation of emission intensity pattern from glass nozzle to the plasma jet tip of a helium plasma jet in ambient air has been observed from the intensified charge-coupled device (ICCD) camera image. The increase of intensity pattern towards the plasma jet tip is an important and fundamental feature of the plasma jet in ambient air. The correlation of this observed pattern with electron impact processes has been studied by computing photon emissivity coefficients (PEC) using the ADAS. The role of various atomic processes involved in this study has also been discussed.

Fiber reinforced polypropylene composites interfacial behavior improvement fabricated by cold plasma jet SiOx nanoparticles deposition

In this study, cold atmospheric pressure plasma jet was adopted to glass fibers surface modification with tetraethyl orthosilicate as a precursor. To enhance the interfacial bonding forces of glass fiber reinforced polypropylene (GFRP) composites, SiOx nanoparticles were polymerized on the fiber surfaces. The effect of two factors (the distance between nozzle and fiber (D) and the treatment time (T)) on the interfacial bonding behavior of GFRP composites was studied. The modified fibers and composites properties, including surface topography, chemical composition, wettability and interfacial mechanical properties, were studied comprehensively. The optimal parameters were obtained at D = 17 mm and T = 12 s. Our results indicated that the interlaminar shear strength of GFRP composites was increased by 30.79% compared to control group. Further studies found that plasma treatment introduced larger surface roughness, surface energy and more oxygen-containing functional groups, which was responsible for the interlaminar shear strength improvement.