Use Of Cold Atmospheric Plasma Research Articles

Machine learning-aided evaluation of oxidative strength of cold atmospheric plasma-treated water.

Plasma medicine is gaining attraction in the medical field, particularly the use of cold atmospheric plasma (CAP) in biomedicine. The chemistry of the plasma is complex, and the reactive oxygen species (ROS) within it are the basis for the biological effect of CAP on the target. Understanding how the oxidative power of ROS responds to diverse plasma parameters is vital for standardizing the effective application of CAP. The proven applicability of machine learning (ML) in the field of medicine is encouraging, as it can also be applied in the field of plasma medicine to correlate the oxidative strength of plasma-treated water (PTW) according to different parameters. In this study, plasma-treated water was mixed with potassium iodide-starch reagent for color formation that could be linked to the oxidative capacity of PTW. Corresponding images were captured resulting from the exposure of the color-forming agent to water treated with plasma for different time points. Several ML models were trained to distinguish the color changes sourced by the oxidative strength of ROS. The AdaBoost Classifier (ABC) algorithm demonstrated better performance among the classification models used by extracting color-based features from the images. Our results, with a test accuracy of 63.5%, might carry a potential for future standardization in the field of plasma medicine with an automated system that can be created to interpret the oxidative properties of ROS in different plasma treatment parameters via ML.

Use of Cold Plasma in the Treatment of Infected Wounds

The fact that chronic and complex wounds are a serious problem, both for those affected and for the health care system, has been known for decades. Most chronic wounds can be healed through targeted treatment of the cause of the wound and optimal wound care. This includes not only phase-adapted modern wound care, but also, in particular, preparation for surgical coverage. The correct preparation of the wound bed, also known as conditioning, plays an important role in this. In recent years, the use of Cold Atmospheric Plasma (CAP) has emerged as a promising new option. Here, the wound is regularly treated with a partially ionized gas. According to studies, this active gas mixture has antimicrobial properties and promotes wound healing by activating cell regenerative processes. To test the efficacy of cold plasma therapy, for complex hard to heel wound with difficult conditions, 40 patients with 41 wounds were included in a retrospective, multicenter observational trial in Italy. The wounds were complex wounds of different genesis that had been present for at least 2 months (> 60 days) were treated with cold atmospheric plasma, generated with the CE approved handheld plasma device plasma care®. The treatment, as an add on to standard wound therapy, was performed once a week and for 1 Minute per treated wound area for an intervention period of 4 weeks. In the intervention period, a total of 41 wounds from 40 patients were treated and measured. Two patients left the trial, the others showed an average wound size reduction of 28% within 30 days. Of all wounds, two were completely closed at the end and 10 wounds even achieved a reduction of at least 40%. Analyzed by initial wound size, 43% of wounds smaller than 18 cm² reduction of 40 %. No improvement or worsening of the wound size was only observed in five wounds. The observational trial showed a reduction in the bacterial load and accelerated wound healing. In addition to the bacterial load, improved wound bed conditioning was also demonstrated. Cold plasma therapy is well suited for locally targeted application to promote wound healing. It is an uncomplicated and quickly applicable method with no known side effects or risks at present.

Staphylococcus aureus strains exhibit heterogenous tolerance to direct cold atmospheric plasma therapy

The global clinical and socioeconomic impact of chronic wounds is substantial. The main difficulty that clinicians face during the treatment of chronic wounds is the risk of infection at the wound site. Infected wounds arise from an accumulation of microbial aggregates in the wound bed, leading to the formation of polymicrobial biofilms that can be largely resistant to antibiotic therapy. Therefore, it is essential for studies to identify novel therapeutics to alleviate biofilm infections. One innovative technique is the use of cold atmospheric plasma (CAP) which has been shown to possess promising antimicrobial and immunomodulatory properties. Here, different clinically relevant biofilm models will be treated with cold atmospheric plasma to assess its efficacy and killing effects. Biofilm viability was assessed using live dead qPCR, and morphological changes associated with CAP evaluated using scanning electron microscopy (SEM). Results indicated that CAP was effective against Candida albicans and Pseudomonas aeruginosa, both as mono-species biofilms and when grown in a triadic model system. CAP also significantly reduced viability in the nosocomial pathogen, Candida auris. Staphylococcus aureus Newman exhibited a level of tolerance to CAP therapy, both when grown alone or in the triadic model when grown alongside C. albicans and P. aeruginosa. However, this degree of tolerance exhibited by S. aureus was strain dependent. At a microscopic level, biofilm treatment led to subtle changes in morphology in the susceptible biofilms, with evidence of cellular deflation and shrinkage. Taken together, these results indicate a promising application of direct CAP therapy in combatting wound and skin-related biofilm infections, although biofilm composition may affect the treatment efficacy.

Cold Atmospheric Plasma-Assisted Direct Deposition of Polypyrrole-Ag Nanocomposites for Flexible Electronic Sensors

Conductive polymers and their composite materials have attracted considerable interest due to their potential applications in sensors, actuators, drug delivery systems, and energy storage devices. Despite their wide range of applications, many challenges remain primarily with respect to the complex synthesis and time-consuming manufacturing steps that are often required in the fabrication process of various devices with conductive polymers. Here, we demonstrate the novel use of cold atmospheric plasma (CAP)-assisted deposition technologies as a solvent-free and scalable approach for in situ polymerization and direct deposition of conductive polypyrrole-silver (PPy-Ag) nanocomposites onto the desired substrates under atmospheric conditions. In this study, a systematic approach with different precursor composition mixtures containing pyrrole as the monomer and AgNO3 as the photoinitiator was investigated to assess the effect of precursor composition on the final chemical, electrical, and mechanical properties of the PPy-Ag nanocomposite thin-film coatings which were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and cyclic bending tests. The characterizations indicated the possibility of fabricating PPy-Ag nanocomposite films with tunable degrees of polymerization and Ag nanoparticle loading by simply varying the percentage of AgNO3 in precursor composition mixtures. Finally, as a proof of concept, the potential use of the PPy-Ag nanocomposite films with different Ag nanoparticle loading percentages was assessed for humidity sensing by measuring their level of change in electrical resistance in the relative humidity range of 12-60%. It is envisioned that the developed CAP-assisted deposition technology can provide a new stepping stone toward scalable additive manufacturing of various functional nanocomposite films for different low-cost and flexible electronic applications.

Use of Cold Atmospheric Plasma in the Treatment of Squamous Cell Carcinoma: in vitro Effects and Clinical Application in Feline Tumors: A Pilot Study

Cold atmospheric plasma (CAP) has shown promising results against squamous cell carcinoma (SCC) in both in vivo and in vitro assays, mainly in humans and mice. Its applicability for treatment of feline tumors, however, remains unknown. This study aimed to evaluate the anticancer effects of CAP on a head and neck squamous cell carcinoma (HNSCC) cell lineage and against a clinical case of cutaneous SCC in a cat. Control and treatment groups employing the HNSCC cell line (SCC-25) were used, the latter exposed to CAP for 60 seconds, 90 seconds, or 120 seconds. The cells were subjected to the MTT assay nitric oxidation assay and thermographic in vitro analyses. The clinical application was performed in one cat with cutaneous SCC (3 sites). The lesions were treated and evaluated by thermographic, histopathological, and immunohistochemical examinations (caspase-3 and TNF-alpha). Treatment of the SCC-25 cells for 90 seconds and 120 seconds resulted in a significant nitrite concentration increase. Decreased cell viability was observed after 24 hours and 48 hours, regardless of exposure time. However, the cell viability reduction observed at 72 hours was significant only in the 120 seconds treatment. In vitro, the temperature decreased for all treatment times, while the plasma induced a slight increase in mean temperature (0.7°C) in the in vivo assay. Two of the 3 clinical tumors responded to the treatment: one with a complete response and the other, partial, while the third (lower lip SCC) remained stable. Both remaining tumors displayed apoptotic areas and increased expression of caspase-3 and TNF-alpha. Adverse effects were mild and limited to erythema and crusting. The CAP exhibited an in vitro anticancer effect on the HNSCC cell line, demonstrated by a dose-dependent cell viability reduction. In vivo, the therapy appears safe and effective against feline cutaneous SCC. The treatment did not result in a clinical response for 1 of 3 lesions (proliferative lower lip tumor), however, a biological effect was still demonstrated by the higher expression of apoptosis indicators.

Selective Effects of Cold Atmospheric Plasma on Bone Sarcoma Cells and Human Osteoblasts.

The use of cold atmospheric plasma (CAP) in oncology has been intensively investigated over the past 15 years as it inhibits the growth of many tumor cells. It is known that reactive oxidative species (ROS) produced in CAP are responsible for this effect. However, to translate the use of CAP into medical practice, it is essential to know how CAP treatment affects non-malignant cells. Thus, the current in vitro study deals with the effect of CAP on human bone cancer cells and human osteoblasts. Here, identical CAP treatment regimens were applied to the malignant and non-malignant bone cells and their impact was compared. Two different human bone cancer cell types, U2-OS (osteosarcoma) and A673 (Ewing's sarcoma), and non-malignant primary osteoblasts (HOB) were used. The CAP treatment was performed with the clinically approved kINPen MED. After CAP treatment, growth kinetics and a viability assay were performed. For detecting apoptosis, a caspase-3/7 assay and a TUNEL assay were used. Accumulated ROS was measured in cell culture medium and intracellular. To investigate the influence of CAP on cell motility, a scratch assay was carried out. The CAP treatment showed strong inhibition of cell growth and viability in bone cancer cells. Apoptotic processes were enhanced in the malignant cells. Osteoblasts showed a higher potential for ROS resistance in comparison to malignant cells. There was no difference in cell motility between benign and malignant cells following CAP treatment. Osteoblasts show better tolerance to CAP treatment, indicated by less affected viability compared to CAP-treated bone cancer cells. This points toward the selective effect of CAP on sarcoma cells and represents a further step toward the clinical application of CAP.

Exploring the Use of Cold Atmospheric Plasma to Overcome Drug Resistance in Cancer.

Drug resistance is a major problem in cancer treatment, as it limits the effectiveness of pharmacological agents and can lead to disease progression. Cold atmospheric plasma (CAP) is a technology that uses ionized gas (plasma) to generate reactive oxygen and nitrogen species (RONS) that can kill cancer cells. CAP is a novel approach for overcoming drug resistance in cancer. In recent years, there has been a growing interest in using CAP to enhance the effectiveness of chemotherapy drugs. In this review, we discuss the mechanisms behind this phenomenon and explore its potential applications in cancer treatment. Going through the existing literature on CAP and drug resistance in cancer, we highlight the challenges and opportunities for further research in this field. Our review suggests that CAP could be a promising option for overcoming drug resistance in cancer and warrants further investigation.

Pilot study on the use of cold atmospheric plasma for preservation of bread

Cold atmospheric plasma (CAP) is used as an emerging technology for food preservation. In this study, CAP treatment has been applied to bakery products for the first time. The aim of the work was to investigate the effect of the use of CAP on the amount of microorganisms during bread storage. Basic physicochemical properties and bread texture were determined during storage for 0, 3, and 6 days. The study material included gluten-free and mixed wheat-rye bread treated with CAP for 2 and 10 min. The results showed that no mesophilic bacteria or fungi were found after ten minutes of the bread exposure to CAP. In addition, only 2-min non-thermal sterilization resulted in complete inhibition of yeast and mould growth in the gluten-free and wheat-rye bread. A decrease in the microbial growth in the bread was noted; however, a simultaneous decrease in the moisture content of the bread was observed. After the application of plasma for 2 or 10 min, both the gluten-free and mixed wheat-rye bread was characterized by reduced humidity, which also resulted in a significant increase in the hardness and a slight increase in the springiness of the bread. The use of CAP in storage of bread is promising; nevertheless, it is necessary to further study the effect of this treatment in bread with improvers, especially with hydrocolloids and fibers.

Effect of cold atmospheric plasma-assisted curing process on the color, odor, volatile composition, and heterocyclic amines in beef meat roasted by charcoal and superheated steam

The use of cold atmospheric plasma (CAP) is fast becoming an emerging curing technology in the meat industry. The aim of this study was to assess CAP-assisted curing of beef meat roasted by charcoal (CR) and superheated steam (SR) in terms of flavor quality and heterocyclic amines (HAs) using electronic nose, GC–MS and UPLC-MS-MS. The CAP-assisted curing increased redness value by 46% and 8% in SR and CR meat respectively. Although CAP-assisted curing had little influence on the odor profile of SR meat, it influenced the odor profile of CR meat. Lipid oxidation-derived off-flavors in CR meat were not significantly (P > 0.05) changed after CAP treatment. However, these off-flavors were significantly (P < 0.05) reduced in SR meat. In addition, CAP-assisted curing did not increase the HAs contents in SR meat. CAP-assisted curing of SR meat improved flavor and did not increase toxic risk of SR meat.

Enhance the inactivation of fungi by the sequential use of cold atmospheric plasma and plasma-activated water: Synergistic effect and mechanism study

Cold atmospheric plasma (CAP) has been widely applied for microbe inactivation. Previous studies revealed that the inactivation efficiency could be improved with the sequential use of plasma-activated water (PAW) after the direct CAP treatment, while the mechanism requires further exploration. In this work, we employed a CAP jet device and investigated the inactivation effect of CAP combined with PAW treatment on two kinds of fungi (Saccharomyces cerevisiae and Aspergillus flavus), and particularly, we examined the synergistic effect by scrutinizing the roles of varied reactive species. Our experimental results showed that short-term CAP treatment combined with the continued long-term (e.g., 120 min) PAW treatment led to significant reduction of Saccharomyces cerevisiae/Aspergillus flavus, with the disinfection effect equivalentto the single CAP approach with much longer treatment time. The comparative analysis revealed that the inactivation of fungi was induced by different reactive oxygen and nitrogen species (RONS) during the combination of CAP and PAW treatments, which had different influences on the fungal morphology, membrane permeability, intracellular RONS and energy metabolism. In the first stage of CAP treatment, the plasma produced ·OH and 1O2, could directly destroy the structure of fungal wall and membrane, leading to cell death. While in the subsequent PAW treatment, the reactive nitrogen species (RNS) could enter cell and influence metabolic activities, leading inactivation of more fungi. The synergistic effect was attributed to the increasing of intracellular 1O2 and ONOO– induced membrane damage, causing the irreparable oxidative damage to mitochondria and energy metabolic system. This mechanistic study may thus provide a new guidance for the optimal application of low-temperature plasma technology in the application of fungal disinfection with high efficiency.

Disinfection of an ambulance using a compact atmospheric plasma device.

The worldwide spread of the coronavirus SARS-CoV-2 has highlighted the need for fast and simple disinfection processes, amongst others for ambulance cars on site. To overcome current drawbacks regarding room disinfection, the use of cold atmospheric plasma in remote operation represents a promising alternative for the disinfection of larger volumes. In this study, a compact plasma system was evaluated regarding its disinfection efficiency inside an ambulance car. The developed plasma device is based on a dielectric barrier discharge (DBD) and operates with ambient air as process gas. The humidified afterglow from the plasma nozzle was introduced into an ambulance car with a volume of approximately 10 m3 while Bacillus atrophaeus endospores, Staphylococcus aureus or Phi 6 bacteriophages dried on different surfaces (PET-films, glass slides or aluminum foil) were exposed to the reactive gas inside the ambulance vehicle at eight different positions. Reductions of spores by more than 4 orders of magnitude were found on all surfaces and positions within 2 h. Due to their higher susceptibility, Phi 6 bacteriophages and S. aureus counts were reduced by at least 4 orders of magnitude within 30 min on all surfaces. The results show that different microorganisms dried on variable surfaces can be inactivated by several orders of magnitude inside an ambulance by plasma gas from of a compact DBD plasma nozzle. Plasma gas generated on site by a DBD plasma nozzle proved to be highly efficient for the disinfection of the interior of an ambulance car. Compact plasma systems could be a viable alternative for the disinfection of vehicles or rooms.

АНАЛИЗ РЕЗУЛЬТАТИВНОСТИ РАЗЛИЧНЫХ МЕТОДОВ ЛЕЧЕНИЯ МИКРОБНОЙ ЭКЗЕМЫ У ДЕТЕЙ

The aim of the study is to analyze the effectiveness of the methods of treatment (MT) of microbial eczema (ME) available in pediatric practice. Materials and methods of research: the article presents the results of the evaluation of efficacy of the methods of treatment of ME in 108 patients aged 1–13 years with ME, taking into account the study of their safety and financial feasibility. ME severity was assessed using IOSTME (Microbial Eczema Severity Evaluation Index). The efficacy of ME therapy was assessed using clinical criteria. Results: with the same safety and clinical efficacy, the use of cold atmospheric plasma (CAP) in the complex therapy of ME has an advantage over the standard treatment method (MT1) and over complex therapy using laser therapy (MT2). The health care efficiency (Km) differed in the use of analytic treatments with the highest proportion of clinical recovery results (complete skin cleansing) in patients receiving complex therapy using CAP (MT3): when using MT1 – in 1 out of 20 cases (5%), with MT2 – in 3 out of 49 patients (6%), with MT3 – in 26 out of 39 cases (67%) (p&lt;0,001). The decrease in the cost of complex treatment methods (MT2 and MT3) was due to a significant reduction in the duration of inpatient treatment: when using MT1 – 14,5 [14,0; 15,0], MT2 – 11,0 [10,0; 12,0], MT3 – 6,0 [6,0; 6,0] bed-days, despite the more expensive medical services for MT2 (1,37 times more expensive than MT1) and MT3 (2,33 times more expensive than MT1 and 1,71 times more expensive than MT2). Conclusion: the use of CAP in the complex treatment of ME is effective, safe and cost-effective.

Green Design of Novel Starch-Based Packaging Materials Sustaining Human and Environmental Health.

A critical overview of current approaches to the development of starch-containing packaging, integrating the principles of green chemistry (GC), green technology (GT) and green nanotechnology (GN) with those of green packaging (GP) to produce materials important for both us and the planet is given. First, as a relationship between GP and GC, the benefits of natural bioactive compounds are analyzed and the state-of-the-art is updated in terms of the starch packaging incorporating green chemicals that normally help us to maintain health, are environmentally friendly and are obtained via GC. Newer approaches are identified, such as the incorporation of vitamins or minerals into films and coatings. Second, the relationship between GP and GT is assessed by analyzing the influence on starch films of green physical treatments such as UV, electron beam or gamma irradiation, and plasma; emerging research areas are proposed, such as the use of cold atmospheric plasma for the production of films. Thirdly, the approaches on how GN can be used successfully to improve the mechanical properties and bioactivity of packaging are summarized; current trends are identified, such as a green synthesis of bionanocomposites containing phytosynthesized metal nanoparticles. Last but not least, bioinspiration ideas for the design of the future green packaging containing starch are presented.

Cold atmospheric plasma selectively induces G0/G1 cell cycle arrest and apoptosis in AR-independent prostate cancer cells.

Purpose: Androgen receptor-independent prostate cancers do not respond to androgen blockage therapies and suffer from high recurrence rate. We aim to contribute to the establishment of novel therapeutic approaches against such malignancies.Materials and Methods: We examined whether and how cold atmospheric plasma delivers selectivity against AR-independent prostate cancers via cell viability, transwell assay, wound healing, cell apoptosis assay, flow cytometry, intracellular hydrogen peroxide determination assay, RONS scavenger assay and western blot using human normal epithelial prostatic cells PNT1A and AR-negative DU145 prostate cancer cells.Results: We show that cold atmospheric plasma could selectively halt cell proliferation and migration in androgen receptor-independent cells as a result of induced cell apoptosis and G0/G1 stage cell cycle arrest, and such outcomes were achieved through modulations on the MAPK and NF-kB pathways in response to physical plasma induced intracellular redox level.Conclusion: Our study reports cold atmospheric plasma induced reduction on the proliferation and migration of androgen receptor-independent prostate cancer cells that offers novel therapeutic insights on the treatment of such cancers, and provides the first evidence on physical plasma induced cell cycle G0/G1 stage arrest that warrants the exploration on the synergistic use of cold atmospheric plasma and drugs such as chemotherapies in eradicating such cancer cells.

The Latest Time Point of Retreatment (LTPR) as a Novel Method to Determine Antibacterial Effects for Binary Use of Cold Atmospheric Plasma and Conventional Agents.

Multi-resistant microorganisms are a long-standing problem for public healthcare, as inactivating those resistant pathogens with conventional antibiotics or antiseptics often no longer achieves the expected clinical success. The aim of this in vitro study was to investigate the antibacterial efficacy of binary combinations of conventional antibacterial agents with cold atmospheric plasma (CAP), when both are applied in non-lethal concentrations. In this study, Enterococcus faecalis biofilms were treated with CAP in binary combinations with benzalkonium chloride (BAC), chlorhexidine (CHX), or ciprofloxacin (CIP), respectively, which were applied in different sequences. In order to evaluate effects of binary use of two different antibacterial approaches, the so-called latest time point of retreatment (LTPR) was defined. For this purpose, regrowth curves of the bacteria were measured following the respective treatment combinations. LTPR is defined as the time component of the inflection point of a normalized regrowth curve and allows the rating and interpretation of single or binary treatments with different agents or approaches. Furthermore, LTPR designates the latest time point where a retreatment appears to be appropriate for preventing regrowth of the bacteria in case the first treatment was not lethal. Here in our study, the binary combination of 10 min CAP with BAC, CHX, or CIP leads to higher LTPRs as compared to single treatments for both sequences of application. Overall, the combination of two antimicrobial approaches is an effective alternative for inactivating bacteria in biofilms instead of a single treatment. Thus, LTPR provides a novel promising way to determine antibacterial effects for single or binary use of given antimicrobial approaches.

Influence of pulse characteristics and power density on stratum corneum permeabilization by dielectric barrier discharge

BackgroundIn recent years, the medical use of cold atmospheric plasma has received much attention. Plasma sources can be suited for widely different indications depending on their physical and chemical characteristics. Being interested in the enhancement of drug transport across the skin by plasma treatment, we evaluated three dielectric barrier discharges (DBDs) as to their potential use in permeabilizing human isolated stratum corneum (SC). MethodsImaging techniques (electrochemical and redox-chemical imaging, fluorescence microscopy), transepithelial electrical resistance measurements and permeation studies were employed to study the permeabilizing effect of different DBD-treatments on SC. ResultsFilamentous μs-pulsed DBDs induced robust pore formation in SC. Increasing the power of the μs-pulsed DBD lead to more pronounced pore formation but might increase the risk of undesired side-effects. Plasma permeabilization was much smaller for the ns-pulsed DBD, which left SC samples largely intact. ConclusionsThe comparison of different DBDs provided insight into the mechanism of DBD-induced SC permeabilization. It also illustrated the need to tailor electrical characteristics of a DBD to optimize it for a particular treatment modality. For future applications in drug delivery it would be beneficial to monitor the permeabilization during a plasma treatment. General significanceOur results provide mechanistic insight into the potential of an emerging interdisciplinary technology – plasma medicine – as a prospective tool or treatment option. While it might become a safe and pain-free method to enhance skin permeation of drug substances, this is also a mechanism to keep in mind when tailoring plasma sources for other uses.

The effect of reactive oxygen and nitrogen species on the structure of cytoglobin: A potential tumor suppressor

Many current anti-cancer therapies rely on increasing the intracellular reactive oxygen and nitrogen species (RONS) contents with the aim to induce irreparable damage, which subsequently results in tumor cell death. A novel tool in cancer therapy is the use of cold atmospheric plasma (CAP), which has been found to be very effective in the treatment of many different cancer cell types in vitro as well as in vivo, mainly through the vast generation of RONS. One of the key determinants of the cell's fate will be the interaction of RONS, generated by CAP, with important proteins, i.e. redox-regulatory proteins. One such protein is cytoglobin (CYGB), a recently discovered globin proposed to be involved in the protection of the cell against oxidative stress. In this study, the effect of plasma-produced RONS on CYGB was investigated through the treatment of CYGB with CAP for different treatment times. Spectroscopic analysis of CYGB showed that although chemical modifications occur, its secondary structure remains intact. Mass spectrometry experiments identified these modifications as oxidations of mainly sulfur-containing and aromatic amino acids. With longer treatment time, the treatment was also found to induce nitration of the heme. Furthermore, the two surface-exposed cysteine residues of CYGB were oxidized upon treatment, leading to the formation of intermolecular disulfide bridges, and potentially also intramolecular disulfide bridges. In addition, molecular dynamics and docking simulations confirmed, and further show, that the formation of an intramolecular disulfide bond, due to oxidative conditions, affects the CYGB 3D structure, thereby opening the access to the heme group, through gate functioning of His117. Altogether, the results obtained in this study (1) show that plasma-produced RONS can extensively oxidize proteins and (2) that the oxidation status of two redox-active cysteines lead to different conformations of CYGB.

Combined effect of cold atmospheric plasma, intrinsic and extrinsic factors on the microbial behavior in/on (food) model systems during storage

Abstract Microbial decontamination by means of cold atmospheric plasma (CAP) offers great potential for treatment of heat-sensitive food products, extending their storage life. CAP is created by applying a high voltage to a gas stream, resulting in microbial inactivation according to different mechanisms. This paper thoroughly assesses the influence of CAP on the storage life of food model systems inoculated with Salmonella Typhimurium. (Food) model systems, with varying intrinsic factors (pH, salt concentration, and food (micro)structure), are treated for 5 min using a dielectric barrier discharge reactor generating a helium‑oxygen plasma. Following treatment, the impact of extrinsic factors is evaluated by storage at 8 °C or 20 °C. During storage, cell densities are determined. Data are fitted with predictive (growth or inactivation) models. As additional experiments indicate that the CAP treatment itself has a limited or even negligible effect on the properties of the model system (pH, aw, (micro)structure), the microbial behavior of CAP treated samples during storage can be attributed to the treatment. CAP treatment can result in microbial reductions up to 2.7 log10 and prolongs storage, however its rate of success is dependent on both extrinsic and intrinsic factors. An important factor is the storage temperature, as recovery of CAP treated cells proves more difficult when stored at 8 °C. At 20 °C, cell growth is merely slowed down. Additionally, at pH 5.5, 6% (w/v) NaCl, osmotic stress is induced on the microorganisms, which results in low cell recovery or further inactivation. The influence of the food (model) structure on the storage behavior is insignificant. Industrial relevance Although being a very promising technology, most studies regarding the use of cold atmospheric plasma (CAP) for food decontamination focus on the inactivation of a target microorganism, in relation to a specific food product. Fundamental knowledge on this non-thermal technology, including its impact on the storage life, is lacking. This study investigates the effect of CAP on the microbial behavior during storage. By performing tests on model systems, for a variation of intrinsic and extrinsic factors, this work renders information on the suitability of this novel technology regarding treatment of a broad spectrum of food products. Moreover, this study demonstrates the limited impact of CAP on the food (model) properties, enhancing the suitability of the technology to be implemented in the food industry.

Gaining Insight In The Selectivity And Plasma-Liquid Chemistry For Plasma Treatment Of Cancer

The use of cold atmospheric plasma, and more specifically plasma-treated liquids (PTL), for cancer treatment is a very promising topic within the field of plasma medicine. [1,2] Simple solutions to be used as PTL (e.g. plasma-treated PBS (pPBS)) are more generally applicable than the plasma-treated media (PTM) that are now mostly reported, because they have a higher stability for storage and are not cell line dependent. [3,4] However, the underlying mechanisms of the plasma-liquid interactions as well as of the selectivity mechanisms of plasma cancer treatment are not yet fully understood. [5,6] In this study, we want to address these two major questions in plasma oncology. Firstly, we investigated the selectivity of plasma treatment for cancer cells vs normal cells. For this purpose, we studied the effect of plasma-treated PBS (pPBS) on the cell cytotoxicity of both non-small cell lung cancer (NSCLC) and normal lung cells. The effects on the cells were monitored by live cell imaging with the IncuCyte ZOOM®. To gain insight in which species are crucial for this selectivity, we measured the concentrations of several reactive oxygen and nitrogen species (RONS, e.g. H2O2, NO2-, NO3-) by UV-VIS spectrophotometry in the pPBS. Secondly, based on the knowledge on which species are important for the killing of and the selectivity towards cancer cells, we aim to promote the formation of these species in the liquid. Therefore, fundamental insight in the plasma-liquid chemistry is needed. In order to gain this insight, we performed both experimental and computational studies on the effect of the composition of the liquid on the formation of RONS in the liquid. For the computational work, we used 0D and 2D models to reveal the most important reactions and species in the gas and liquid phase. Experimentally, concentrations of RONS in the liquid were measured by both UV-VIS spectrophotometry (e.g. H2O2, NO2-, NO3-) and electron paramagnetic resonance (EPR, e.g. OH, O3, O, 1O2). The effect of chlorine concentration, buffer capacity and pH of the liquid will be presented.

Use of cold-atmospheric plasma in oncology: a concise systematic review.

Background:Cold-atmospheric plasma (CAP) is an ionized gas produced at an atmospheric pressure. The aim of this systematic review is to map the use of CAP in oncology and the implemented methodologies (cell targets, physical parameters, direct or indirect therapies).Methods:PubMed, the International Clinical Trials Registry Platform and Google Scholar were explored until 31 December 2017 for studies regarding the use of plasma treatment in oncology (in vitro, in vivo, clinical trials).Results:190 original articles were included. Plasma jets are the most-used production systems (72.1%). Helium alone was the most-used gas (35.8%), followed by air (26.3%) and argon (22.1%). Studies were mostly in vitro (94.7%) and concerned direct plasma treatments (84.2%). The most targeted cancer cell lines are human cell lines (87.4%), in particular, in brain cancer (16.3%).Conclusions:This study highlights the multiplicity of means of production and clinical applications of the CAP in oncology. While some devices may be used directly at the bedside, others open the way for the development of new pharmaceutical products that could be generated at an industrial scale. However, its clinical use strongly needs the development of standardized reliable protocols, to determine the more efficient type of plasma for each type of cancer, and its combination with conventional treatments.