Long-lived Reactive Species Research Articles

The Development of New Nanocomposite Polytetrafluoroethylene/Fe2O3 NPs to Prevent Bacterial Contamination in Meat Industry.

The bacterial contamination of cutting boards and other equipment in the meat processing industry is one of the key reasons for reducing the shelf life and consumer properties of products. There are two ways to solve this problem. The first option is to create coatings with increased strength in order to prevent the formation of micro damages that are favorable for bacterial growth. The second possibility is to create materials with antimicrobial properties. The use of polytetrafluoroethylene (PTFE) coatings with the addition of metal oxide nanoparticles will allow to the achieving of both strength and bacteriostatic effects at the same time. In the present study, a new coating based on PTFE and Fe2O3 nanoparticles was developed. Fe2O3 nanoparticles were synthesized by laser ablation in water and transferred into acetone using the developed procedures. An acetone-based colloidal solution was mixed with a PTFE-based varnish. Composites with concentrations of Fe2O3 nanoparticles from 0.001-0.1% were synthesized. We studied the effect of the obtained material on the generation of ROS (hydrogen peroxide and hydroxyl radicals), 8-oxoguanine, and long-lived active forms of proteins. It was found that PTFE did not affect the generation of all the studied compounds, and the addition of Fe2O3 nanoparticles increased the generation of H2O2 and hydroxyl radicals by up to 6 and 7 times, respectively. The generation of 8-oxoguanine and long-lived reactive protein species in the presence of PTFE/Fe2O3 NPs at 0.1% increased by 2 and 3 times, respectively. The bacteriostatic and cytotoxic effects of the developed material were studied. PTFE with the addition of Fe2O3 nanoparticles, at a concentration of 0.001% or more, inhibited the growth of E. coli by 2-5 times compared to the control or PTFE without NPs. At the same time, PTFE, even with the addition of 0.1% Fe2O3 nanoparticles, did not significantly impact the survival of eukaryotic cells. It was assumed that the resulting composite material could be used to cover cutting boards and other polymeric surfaces in the meat processing industry.

Triterpenoids and ultrasound dual-catalytic nanoreactor ignites long-lived hypertoxic reactive species storm for deep tumor treatment

Inducing redox imbalance in cancer cells aided by external stimuli is a promising strategy to treat cancer. However, maximizing efficacious reactive species content with durable effects in deep tumors remains to be challenging. Here, we report an herbal medicine-based nanoreactor (OH7) self-assembled by oleanolic acid (OA) and two sonosensitizers. OH7 couples two cascade reactions under sonication, including dual-sonosensitizer-participated consecutive reactions for generating long-living peroxyl radical (ROO•) and OA-participated serial reactions for forming highly cytotoxic peroxynitrite (ONOO−). The site-directed reactive species burst exerts excellent cytotoxicity on two-dimensional cancer cell cultures and multicellular tumor spheroids. The high elasticity of OH7 for deep tumor transportation, the enhanced intratumoral convection by ultrasound, and the formation of ONOO− to destroy extracellular matrix jointly facilitate satisfactory penetration depth of sonosensitizers. Of note, the deep penetration and the long-lived hypertoxic reactive species generating ability can realize effective tumor inhibition by systemic administration. This study opens up new insights into the reactive species-related bioactive mechanisms to support green development of biocompatible high-performance sonocatalytic nanoreactor for potential clinical applications.

Power dependence of reactive species generation in a water falling film dielectric barrier discharge system

The short-lived and long-lived reactive species generated in plasma-liquid interactions determine their potential applications in wastewater purification and plant growth stimulation. In this work, plasma-generated reactive species including hydroxyl radicals (∙OH), hydrogen peroxide (H2O2), ozone (O3), hydronium (H3O+), and nitrate (NO3-) were quantified in a water falling film dielectric barrier discharge system. The reaction kinetics of short-lived ∙OH were analyzed based on the quantification of ∙OH and degradation of salicylic acid, focusing on the contribution and utilization of ∙OH. The interconversion of ∙OH with H2O2 and O3 was also calculated. The accumulation rates of H3O+ and NO3- indicated the potential of this dielectric barrier discharge system in sustainable fertilizer production. In addition, the toxicity prediction of salicylic acid degradation intermediates and the cultivation of soybean seeds verified the feasibility of plasma-liquid interactions in organic wastewater recycling.

Cell death induced in glioblastoma cells by Plasma-Activated-Liquids (PAL) is primarily mediated by membrane lipid peroxidation and not ROS influx

Since first identified in 1879, plasma, the fourth state of matter, has been developed and utilised in many fields. Nonthermal atmospheric plasma, also known as cold plasma, can be applied to liquids, where plasma reactive species such as reactive Oxygen and Nitrogen species and their effects can be retained and mediated through plasma-activated liquids (PAL). In the medical field, PAL is considered promising for wound treatment, sterilisation and cancer therapy due to its rich and relatively long-lived reactive species components. This study sought to identify any potential antagonistic effect between antioxidative intracellularly accumulated platinum nanoparticles (PtNPs) and PAL. We found that PAL can significantly reduce the viability of glioblastoma U-251MG cells. This did not involve measurable ROS influx but instead lead to lipid damage on the plasma membrane of cells exposed to PAL. Although the intracellular antioxidative PtNPs showed no protective effect against PAL, this study contributes to further understanding of principle cell killing routes of PAL and discovery of potential PAL-related therapy and methods to inhibit side effects.

Penetration effect of the kINPen plasma jet investigated with a 3D agar-entrapped bacteria model

Elucidation of the penetration effect of cold atmospheric plasma on human tissues is essential for achieving a better comprehension of its diverse biomedical applications. The aim of this work was to investigate the penetration effect of the kINPen plasma jet, one of the most extensively studied plasma sources, using a novel 3D agar-entrapped bacteria model. In this study, 2.0 % agar was used as the main skeleton of the 3D model to simulate human skin tissue. Then, the feasibility and validity of evaluating the kINPen’s tissue penetration effect based on this 3D model system were explored. Our results showed that the bacteria colonies could grow uniformly within the 2 % agar skeleton. The kINPen exhibited a dose-dependent inhibitory effect on bacterial growth in the 3D model (P < 0.05). Further experiments revealed that the penetration effect of the kINPen is closely related to the long-lived active species (e.g., H2O2) produced by the plasma jet. By performing direct and indirect treatments, we found that possible components other than long-lived reactive species, such as short-lived reactive species, electric fields, UV light and electrons, play a non-negligible role in agar-entrapped bacteria inactivation. In comparison to the potassium iodide-starch model, the 3D agar-entrapped bacteria model can more objectively and sensitively reflect the penetration effect of the kINPen. Finally, the 3D agar-entrapped bacteria model is expected to be an effective assessment tool for evaluating biologically relevant penetration effect of cold atmospheric plasma.

TRATAMIENTO DE AGUA CON UNA DESCARGA CORONA PULSADA

One of the fastest growing technological applications in recent years in the area of non-thermal plasmas is the treatment of water with discharges in (and in contact with) liquids. Reactive chemical species are generated in the plasma in the gas phase and enter the liquid by diffusion or are generated at the gas-liquid interface, thus changing its physicochemical properties, without the addition of external chemical compounds. Depending on the form of application of the plasma, well-differentiated effects can be achieved: on the one hand, the purification of water through the degradation of organic pollutants, and on the other, its activation, through long-lived reactive species, for later use in seeds and food treatments. In this work, the first results obtained in the water treated with a pulsed corona discharge under different exposure times are reported. In particular, measurement results of indigo carmine degradation; electric conductivity; pH; aqueous concentrations of reactive species, such as nitrate, nitrite, hydrogen peroxide and ozone, are reported. The results are discussed and compared with published data.

Investigation of different solutions activated by air plasma jet and their anticancer effect

In the field of plasma biomedicine, research on a plasma-activated medium (PAM) has attracted increasing attention in recent years because of its excellent characteristics. In this study, we used an atmospheric pressure air plasma jet to treat four different solutions: de-ionized water, RPMI 1640 medium, phosphate buffered saline (PBS), and saline. In order to investigate the property differences of different PAM, we mainly analyzed the physical and chemical properties and liquid-phase active species of different PAM and evaluated the inactivation of A549 lung cancer cells. The results show that the concentrations of long-lived reactive species (H2O2, NO2−, and NO3−) in different PAM increased with increasing treatment time. Biological experiments showed that the antitumor effects were in the order of PBS &amp;gt; saline &amp;gt; RPMI 1640 medium, and the best inactivation effect of plasma-activated PBS for 12 min was 89%. Meanwhile, plasma-activated PBS effectively promoted apoptosis in A549 cells, and the highest apoptosis rate was 91.3%. Therefore, this study demonstrates the medical application of different PAM in killing cancer cells and promotes the understanding of plasma–liquid interaction.

Optical absorption spectroscopy of reactive oxygen and nitrogen species in a surface dielectric barrier discharge

A twin surface dielectric barrier discharge (SDBD) ignited in a dry synthetic air gas stream is studied regarding the formation of reactive oxygen and nitrogen species (RONS) and their impact on the conversion of admixed n-butane. The discharge is driven by a damped sinusoidal voltage waveform at peak-to-peak amplitudes of 8 kVpp–13 kVpp and pulse repetition frequencies of 250 Hz–4000 Hz. Absolute densities of O3, NO2, NO3, as well as estimates of the sum of the densities of N2O4 and N2O5 are determined temporally resolved by means of optical absorption spectroscopy using a laser driven broadband light source, suitable interference filters, and a photodiode detector. The measured densities are acquired across the center of the reactor chamber as well as at the outlet of the chamber. The temporal and spatial evolution of the species’ densities is correlated to the conversion of n-butane at concentrations of 50 ppm and 400 ppm, measured by means of flame ionization detectors. The n-butane is admixed either before or after the reactor chamber, in order to separate the impact of short- and long-lived reactive species on the conversion process. It is found that, despite the stationary conversion at the selected operating points, at higher voltages and repetition frequencies the densities of the measured species are not in steady state. Based on the produced results it is presumed that the presence of n-butane modifies the formation and consumption pathways of O3. At the same time, there is no significant impact on the formation of dinitrogen oxides (N2O4 and N2O5). Furthermore, a comparatively high conversion of n-butane, when admixed at the outlet of the reactor chamber is observed. These findings are discussed together with known rate coefficients for the reactions of n-butane with selected RONS.

Antibacterial behavior of organosilicon composite with nano aluminum oxide without influencing animal cells

A technology for producing a nanocomposite based on the borsiloxane polymer and aluminum oxide nanoparticles (Al2O3 NPs) has been developed. Nanocomposites containing 0.001, 0.01, and 0.1 wt% Al2O3 NPs have been created. It has been shown that the nanocomposite with any content of Al2O3 NPs did not lose the main rheological properties of borsiloxane. The resulting nanomaterial is capable of generating reactive oxygen species (ROS) such as hydrogen peroxide and hydroxyl radicals. The rate of ROS generation increases up to 3 times with an increase in the concentration of Al2O3 NPs. It has been shown that the nanocomposite leads to the formation of long-lived reactive protein species, and is also the reason for the appearance of such a key biomarker of oxidative stress as 8-oxoguanine in DNA. The intensity of the process increases with an increase in the concentration of Al2O3 NPs. Moreover, it was found that bacterial cells adhere to the surfaces of the nanocomposite (reduces the number of bacteria on the substrate by 39 times), and the nanocomposite can detach bacterial cells not only from the surfaces, but also from wetted substrates. The ability to capture bacterial cells is primarily associated with the properties of the polymer; they are weakly affected Al2O3 NPs. The nanocomposite is non-toxic to eukaryotic cells, the surface of the nanocomposite is suitable for eukaryotic cells for colonization. Due to unique physical properties, low cytotoxicity and antimicrobial action, this nanocomposite can be used in medicine and prosthetics.

Bacteriostatic and Cytotoxic Properties of Composite Material Based on ZnO Nanoparticles in PLGA Obtained by Low Temperature Method.

A low-temperature technology was developed for producing a nanocomposite based on poly (lactic-co-glycolic acid) and zinc oxide nanoparticles (ZnO-NPs), synthesized by laser ablation. Nanocomposites were created containing 0.001, 0.01, and 0.1% of zinc oxide nanoparticles with rod-like morphology and a size of 40–70 nm. The surface of the films from the obtained nanomaterial was uniform, without significant defects. Clustering of ZnO-NPs in the PLGA matrix was noted, which increased with an increase in the concentration of the dopant in the polymer. The resulting nanomaterial was capable of generating reactive oxygen species (ROS), such as hydrogen peroxide and hydroxyl radicals. The rate of ROS generation increased with an increase in the concentration of the dopant. It was shown that the synthesized nanocomposite promotes the formation of long-lived reactive protein species, and is also the reason for the appearance of a key biomarker of oxidative stress, 8-oxoguanine, in DNA. The intensity of the process increased with an increase in the concentration of nanoparticles in the matrix. It was found that the nanocomposite exhibits significant bacteriostatic properties, the severity of which depends on the concentration of nanoparticles. In particular, on the surface of the PLGA–ZnO-NPs composite film containing 0.001% nanoparticles, the number of bacterial cells was 50% lower than that of pure PLGA. The surface of the composite is non-toxic to eukaryotic cells and does not interfere with their adhesion, growth, and division. Due to its low cytotoxicity and bacteriostatic properties, this nanocomposite can be used as coatings for packaging in the food industry, additives for textiles, and also as a material for biomedicine.

Novel Biocompatible with Animal Cells Composite Material Based on Organosilicon Polymers and Fullerenes with Light-Induced Bacteriostatic Properties.

A technology for producing a nanocomposite based on the borsiloxane polymer and chemically unmodified fullerenes has been developed. Nanocomposites containing 0.001, 0.01, and 0.1 wt% fullerene molecules have been created. It has been shown that the nanocomposite with any content of fullerene molecules did not lose the main rheological properties of borsiloxane and is capable of structural self-healing. The resulting nanomaterial is capable of generating reactive oxygen species (ROS) such as hydrogen peroxide and hydroxyl radicals in light. The rate of ROS generation increases with an increase in the concentration of fullerene molecules. In the absence of light, the nanocomposite exhibits antioxidant properties. The severity of antioxidant properties is also associated with the concentration of fullerene molecules in the polymer. It has been shown that the nanocomposite upon exposure to visible light leads to the formation of long-lived reactive protein species, and is also the reason for the appearance of such a key biomarker of oxidative stress as 8-oxoguanine in DNA. The intensity of the process increases with an increase in the concentration of fullerene molecules. In the dark, the polymer exhibits weak protective properties. It was found that under the action of light, the nanocomposite exhibits significant bacteriostatic properties, and the severity of these properties depends on the concentration of fullerene molecules. Moreover, it was found that bacterial cells adhere to the surfaces of the nanocomposite, and the nanocomposite can detach bacterial cells not only from the surfaces, but also from wetted substrates. The ability to capture bacterial cells is primarily associated with the properties of the polymer; they are weakly affected by both visible light and fullerene molecules. The nanocomposite is non-toxic to eukaryotic cells, the surface of the nanocomposite is suitable for eukaryotic cells for colonization. Due to the combination of self-healing properties, low cytotoxicity, and the presence of bacteriostatic properties, the nanocomposite can be used as a reusable dry disinfectant, as well as a material used in prosthetics.

Degradation of tetracycline in water by gas–liquid plasma in conjunction with rGO-TiO2 nanocomposite

Tetracycline (TC) is an antibiotic mainly used in livestock production and respiratory infection. Traditional methods are not effective in removing TC from solution. In this study, TC was degraded by gas–liquid plasma in the presence of rGO-TiO2 in solution. The rGO-TiO2 was prepared by modified hummers and hydrothermal method. The electrical and optical properties of the gas–liquid discharge plasma were studied and the produced long-lived reactive species were analyzed by spectrophotometer. The degradation efficiency of TC was improved by 41.4% after plasma treatment for 12 min in presence of 30 mg l−1 rGO-TiO2 compared to that with plasma alone. The degradation efficiency increased with increasing discharge power, but as the initial concentration was increased from 20 to 80 mg l−1, the degradation efficiency of TC decreased. The initial pH had no significant effect on the degradation of TC. The intermediate products were determined by UV–vis spectrophotometry and ESI (+)–MS, and the degradation mechanism was analyzed. The reactive species, including O3, ·OH, and H2O2, etc., produced in the plasma/catalyst system attracted electron-rich functional groups (amino group, aromatic ring, and double bond). Therefore, the gas–liquid plasma/catalyst system could be an effective and promising method for pharmaceutical wastewater treatment in future.

Effect of solution pH on the characteristics of pulsed gas–liquid discharges and aqueous reactive species in atmospheric air

Solution pH is a significant parameter that affects the electrical characteristics of gas–liquid discharges and thus potentially produces different plasma chemistries for different plasma-engineered applications. In this study, the discharge characteristics and long-lived aqueous reactive species under different initial pH conditions were investigated. It was found that the discharge contained three phases in one pulse cycle, which occurred at the pulse rising edge, the falling edge, and between the rising and falling edges. The discharge intensity and average power at an initial solution pH of 7.0 are much lower than those obtained at an initial solution pH of 5.0 and 9.0. In contrast, the density ratio of N2 (C3Πu, v = 1)/N2 (C3Πu, v = 0) is much higher under neutral solution conditions, indicating that the relatively high vibrational energy was obtained in the gas–liquid discharge plasma. Concentrations of aqueous species H2O2, NO2–, and NO3– are higher at the initial pH of 9.0, indicating that different plasma intensities and chemical compositions (H+ and OH–) are involved in their generation and consumption processes. This study provides insights into understanding and controlling the characteristics of the gas–liquid discharge under different solution conditions.

Surface barrier discharges for Escherichia coli biofilm inactivation: Modes of action and the importance of UV radiation.

Cold plasma generated in air at atmospheric pressure is an extremely effective antimicrobial agent, with proven efficacy against clinically relevant bacterial biofilms. The specific mode of bacterial inactivation is highly dependent upon the configuration of the plasma source used. In this study, the mode of microbial inactivation of a surface barrier discharge was investigated against Escherichia coli biofilms grown on polypropylene coupons. Different modes of exposure were considered and it was demonstrated that the long-lived reactive species created by the plasma are not solely responsible for the observed microbial inactivation. It was observed that a synergistic interaction occurs between the plasma generated long-lived reactive species and ultraviolet (UV) photons, acting to increase the antimicrobial efficacy of the approach by an order of magnitude. It is suggested that plasma generated UV is an important component for microbial inactivation when using a surface barrier discharge; however, it is not through the conventional pathway of direct DNA damage, rather through the synergistic interaction between liquid in the biofilm matrix and long-lived chemical species created by the discharge.

Facile synthesis of binary metal substituted copper oxide as a solar light driven photocatalyst and antibacterial substitute

This work presents the synthesis of Cu0.95Mn0.05O (CMO), Cu0.95Ag0.05O (CAO), and Cu0.9Mn0.05Ag0.05O (CMAO) samples via wet chemical route for photocatalytic and antibacterial applications. The phase, morphology, chemical composition, and absorption range of the transition metal substituted CuO samples were investigated using various techniques such as PXRD, FESEM, EDX, and UV/Visible spectroscopy . The photocatalytic and antibacterial aptitude of all the synthesized samples was tested using methylene blue (MB) and bacterial strains. The results of application studies showed that the CMAO sample has a greater potential for dye degradation and bacterial strain destruction because of its long-lived photo-generated reactive species. More precisely, among all the synthesized samples, the CMAO sample showed excellent photocatalytic activity and degraded 83.9% dye at a higher rate constant value (0.0127 min−1). Moreover, the CMAO sample also showed better bactericidal activity against Gram-positive (S. aureus) and Gram-negative bacterial strains (E. coli). Actually, components of the bacterial cell membrane are also organic like organic dyes, so they are likely to degrade by photo-generated species. The results revealed that binary metal substituted CuO (CMAO) has an excellent ability to kill bacteria and eliminate toxic dyes from industrial effluents.

Micronucleated erythrocytes in peripheral blood from neonate rats fed by nursing mothers exposed to X-rays.

Most women with breast cancer can become pregnant and give birth while undergoing radiation therapy and breastfeeding is generally not contraindicated. The induction of long-lived reactive species in proteins, such as casein by X-ray radiation and DNA damage to unexposed organisms, has been shown when ingesting irradiated cheese. To determine whether exposing lactating rats to X-rays increases the number of micronucleated erythrocytes (MNEs) in peripheral blood of their unexposed or breastfeeding rat pups, 15 female Wistar rats were divided into three groups: Negative control; Experimental group exposed to X-rays, and group exposed to X-rays plus vitamin C. The mothers of groups 2 and 3 were irradiated for three consecutive days after giving birth, returning them to their respective cages each time to continue lactation. A blood sample was taken from the mothers and pups at 0, 24, and 48 hr. Blood smears were stained with acridine orange to analyze MNEs. In mother rats, the frequency of micronucleated polychromatic erythrocytes (MNPCEs) increased significantly at 24 and 48 hr in both study groups exposed to radiation. Likewise, in rat pups the MNPCE and MNE frequencies increased in both groups with radiation and radiation plus vitamin C at 24 and 48 hr, and a protection from vitamin C was observed. In conclusion, the genotoxic damage produced in rat pups that were lactated by mothers irradiated with X-rays is possibly due to the effect of long-lived reactive species that were formed in the breast milk of female Wistar rats during the irradiation process.

Role of Short- and Long-Lived Reactive Species on the Selectivity and Anti-Cancer Action of Plasma Treatment In Vitro.

Simple SummaryOne fundamental feature that has emerged from in vitro application of cold plasmas in cancer treatment is the key role of the liquid phase covering the cells. In the present work, we investigated the effect of direct and indirect plasma treatments on two cancer and three normal cell lines to assess the benefits of one treatment over the other in terms of death of tumor versus healthy cells. Our results demonstrate that indirect plasma treatment is as efficient at killing tumor cells as an appropriate combination of H2O2, NO2− and acidic pH in ad hoc solutions, while sparing normal cells. However, direct plasma treatment is far more efficient at killing normal than tumor cells, and we provide evidence that short- and long-lived reactive species contribute synergistically to kill normal cells, while having an additive effect regarding tumor cell death. Collectively, our results call the use of plasma-activated liquid in cancer treatment into question.(1) Plasma-activated liquids (PAL) have been extensively studied for their anti-cancer properties. Two treatment modalities can be applied to the cells, direct and indirect plasma treatments, which differ by the environment to which the cells are exposed. For direct plasma treatment, the cells covered by a liquid are present during the plasma treatment time (phase I, plasma ON) and the incubation time (phase II, plasma OFF), while for indirect plasma treatment, phase I is cell-free and cells are only exposed to PAL during phase II. The scope of this work was to study these two treatment modalities to bring new insights into the potential use of PAL for cancer treatment. (2) We used two models of head and neck cancer cells, CAL27 and FaDu, and three models of normal cells (1Br3, NHK, and RPE-hTERT). PBS was used as the liquid of interest, and the concentration of plasma-induced H2O2, NO2− and NO3−, as well as pH change, were measured. Cells were exposed to direct plasma treatment, indirect plasma treatment or reconstituted buffer (PBS adjusted with plasma-induced concentrations of H2O2, NO2−, NO3− and pH). Metabolic cell activity, cell viability, lipid peroxidation, intracellular ROS production and caspase 3/7 induction were quantified. (3) If we showed that direct plasma treatment is slightly more efficient than indirect plasma treatment and reconstituted buffer at inducing lipid peroxidation, intracellular increase of ROS and cancer cell death in tumor cells, our data also revealed that reconstituted buffer is equivalent to indirect plasma treatment. In contrast, normal cells are quite insensitive to these two last treatment modalities. However, they are extremely sensitive to direct plasma treatment. Indeed, we found that phase I and phase II act in synergy to trigger cell death in normal cells and are additive concerning tumor cell death. Our data also highlight the presence in plasma-treated PBS of yet unidentified short-lived reactive species that contribute to cell death. (4) In this study, we provide strong evidence that, in vitro, the concentration of RONS (H2O2, NO2− and NO3−) in combination with the acidic pH are the main drivers of plasma-induced PBS toxicity in tumor cells but not in normal cells, which makes ad hoc reconstituted solutions powerful anti-tumor treatments. In marked contrast, direct plasma treatment is deleterious for normal cells in vitro and should be avoided. Based on our results, we discuss the limitations to the use of PAL for cancer treatments.

Spatio-temporal evolution characteristics and pattern formation of a gas–liquid interfacial AC current argon discharge plasma with a deionized water electrode

A discharge ignited by an AC power source in contact with deionized water as one of the electrodes is investigated. Immediately after initiation, the discharge exhibits a unique phenomenon: the gas-phase discharge is extended into the liquid. Later, a cone-like structure is observed at the liquid surface. Synchronous monitoring of current–voltage characteristics and liquid properties versus time suggests that the discharge shapes are functions of the liquid properties. The spatio-temporal profiles indicate the potential effects of water, ambient air impurities, and metastable argon on the discharge chemistry. This becomes more obvious near the liquid surface due to increasing production of various transient reactive species such as ·OH and NO·. Moreover, it is revealed that thermalization of the rotational population distributions of the rotational states in the Q 1 branch of the OH band ro-vibrational system is influenced by the humid environment near the liquid surface. In addition, the transient behaviors of instantaneous concentrations of long-lived reactive species (LRS) such as H2O2, and are observed with lengthening the discharge time. The production of multiple transient and LRS proposes AC excited gas–liquid argon discharge as a potential applicant in industrial wastewater cleaning, clinical medicine, and agriculture.

Manufacturing and Study of Mechanical Properties, Structure and Compatibility with Biological Objects of Plates and Wire from New Ti-25Nb-13Ta-5Zr Alloy

A Ti–25Nb–13Ta–5Zr alloy was produced and studied in this work, and plates and wires were made from this alloy. It is shown that the Ti–25Nb–13Ta–5Zr alloy has the required mechanical properties and a β-crystal phase. Microstructures were present on the surface of the alloy with a height of several hundred nm, located at a distance of 1.5–2 μm from each other. Ti–25Nb–13Ta–5Zr was superior to nitinol in terms of the formation of long-living reactive protein species and the generation of reactive oxygen species. Cell cultivation on Ti–25Nb–13Ta–5Zr alloy surfaces revealed a significant mitotic index (2%) and a small number of nonviable cells (&lt;5%). The cells were actively attached and spread over the alloy. The biocompatibility of Ti–25Nb–13Ta–5Zr was verified by experiments on the implantation of the alloy in the form of plates and coiled wires. The surface morphology of the specimens after biological trials was not significantly altered. The experimental data we obtained suggest that Ti–25Nb–13Ta–5Zr is suitable for potential applications in biology and medicine.

Preparation, structural and microstructural characterization of Ti–30Nb–10Ta–5Zr alloy for biomedical applications

Ti–30Nb–10Ta–5Zr alloy was produced and studied in the work. Plates and wires were made of this alloy. The alloy was shown to have pure β-crystalline phase and to possess the required mechanical properties. Microstructures with a height of the order of several hundred nm, located at a distance of 1.5–2.0 μm were observed on the surface of the alloy. From the point of view of reactive oxygen species generation and long-lived reactive protein species formation, the Ti–30Nb–10Ta–5Zr alloy is more preferrable than nitinol. Cultivation of cell cultures on Ti–30Nb–10Ta–5Zr surfaces resulted in high mitotic index (2%) and low content of non-viable cells (<5%). The cells were actively attaching and spreading on the alloy. Biocompatibility of Ti–30Nb–10Ta–5Zr was confirmed by the experiments on implantation of the alloy as plates and coiled wires. The surface morphology of the specimens did not alter significantly after the biological trials. It can be suggested that Ti–30Nb–10Ta–5Zr alloy is an appropriate material for potential medical applications.