Cold Atmospheric Pressure Plasma Treatment Research Articles

Plasma Medical Oncology: Long-Term Results With Focus On Immunity Research

Background The morbidity and mortality of advanced-stage head and neck squamous cell carcinoma (HNSCC) are still high, despite innovative advances in treatment1. Current research strategies pay a growing attention on cold atmospheric pressure plasma (CAP). Objective In this article, selected clinical results in CAP therapy of palliative HNSCC patients are presented. The current state of preclinical and clinical research on plasma medical oncology is summarized, with special regard to immunity aspects. Results A prospective observation study2 investigated the therapeutic effect of CAP treatment in locally advanced HNSCC (UICC IV) patients who failed to response to the standard treatment. In this palliative intended trial one third of the patients showed a remarkable partial tumor remission under CAP therapy. The patients could be confidently identified as a responder or non-responder to CAP treatment within the first two weeks after intervention. In the group of responder patients, the tumor surface decreased by 80% in size compared to the baseline. The effectiveness of CAP got lost after a long plateau phase. Both, the effectivity and the loss of effectivity can be interpreted by new immunological insights. Apart from the active components of plasma (e.g. ROS/RNS), that modify the redox level and the activation level of signaling pathways in cancer and immune cells, the regulation of immunogenic cells is a key component. Conclusion Plasma therapy has the ability to locally effect the immune system and to modify the tumor microenvironment- opening perspectives for improved therapeutic concepts.

Computational And Experimental Study Of The Impact Of Plasma On The Human Epidermal Growth Factor And Its Implications For Wound Healing And Cancer Treatment

The human epidermal growth factor (hEGF) plays an important role in wound healing as well as in cancer treatment. It is known to trigger chemotaxis, mitogenesis, motogenesis, and cytoprotection, allowing the promotion of cancer growth [1]. On the other hand, exactly these triggers are beneficial for wound healing [2]. Previous studies have shown that cold atmospheric pressure plasma (CAP) treatment of proteins can lead to oxidation, causing structural and conformational changes [3]. In this study, we perform computer simulations and experiments to investigate the impact of plasma treatment on hEGF. Conformational changes with different degrees of oxidation, corresponding to short or longer CAP treatment times, are studied by combining simulation results with Fourier transform infrared spectroscopy. Additional experiments are performed with circular dichroism spectroscopy to verify the simulated conformational changes. The results, being qualitatively in good agreement, indicate a more flexible structure after oxidization, due to conformational changes and breakage of disulfide bonds. Docking simulations reveal that a low oxidation degree does not have a significant influence on the binding affinity of hEGF to its receptor. However, a highly oxidized hEGF exhibits less interaction, probably ultimately affecting cell proliferation by either assisting or inhibiting the process. The results indicate that a low amount of oxidation, comparable to the medical CAP treatment times used for wound healing, does not cause significant changes of the structure of the hEGF protein and thus has only little impact on the interaction of hEGF with its receptor. A significant effect on the structural conformation of hEGF and the binding energy with EGFR can be achieved by higher oxidation degrees, which might ultimately lead to inhibition of cell growth or proliferation. This might be important in cancer treatment by means of CAP, as higher doses of oxidation arrest the cell growth, leading to apoptosis or even necrosis [4,5,6].

Cold atmospheric pressure plasma causes protein denaturation and endoplasmic reticulum stress in Saccharomyces cerevisiae.

Cold atmospheric pressure plasma (CAP) does not cause thermal damage or generate toxic residues; hence, it is projected as an alternative agent for sterilization in food and pharmaceutical industries. The fungicidal effects of CAP have not yet been investigated as extensively as its bactericidal effects. We herein examined the effects of CAP on yeast proteins using a new CAP system with an improved processing capacity. We demonstrated that protein ubiquitination and the formation of protein aggregates were induced in the cytoplasm of yeast cells by the CAP treatment. GFP-tagged Tsa1 and Ssa1, an H2O2-responsive molecular chaperone and constitutively expressed Hsp70, respectively, formed cytoplasmic foci in CAP-treated cells. Furthermore, Tsa1 was essential for the formation of Ssa1-GFP foci. These results indicate that the denaturation of yeast proteins was caused by CAP, at least partially, in a H2O2-dependent manner. Furthermore, misfolded protein levels in the endoplasmic reticulum (ER) and the oligomerization of Ire1, a key sensor of ER stress, were enhanced by the treatment with CAP, indicating that CAP causes ER stress in yeast cells as a specific phenomenon to eukaryotic cells. The pretreatment of yeast cells at 37°C significantly alleviated cell death caused by CAP. Our results strongly suggest that the induction of protein denaturation is a primary mechanism of the fungicidal effects of CAP.

Anti-tumor effects of cold atmospheric pressure plasma on vestibular schwannoma demonstrate its feasibility as an intra-operative adjuvant treatment.

Vestibular schwannoma (VS), although a benign intracranial tumor, causes morbidities by brainstem compression. Since chemotherapy is not very effective in most Nf2-negative schwannomas, surgical removal or radiation therapy is required. However, depending on the size and site of the tumor, these approaches may cause loss of auditory or vestibular functions, and severely decrease the post-surgical wellbeing. Here, we examined the feasibility of cold atmospheric pressure plasma (CAP) as an intra-operative adjuvant treatment for VS after surgery. Cell death was efficiently induced in both human HEI-193 and mouse SC4 VS cell lines upon exposure to CAP for seven minutes. Interestingly, both apoptosis and necroptosis were simultaneously induced by CAP treatment, and cell death was not completely inhibited by pan-caspase and receptor-interacting serine/threonine-protein kinase 1 (RIK1) inhibitors. Upon CAP exposure, cell death phenotype was similarly observed in patient-derived primary VS cells and tumor mass. In addition, CAP exposure after the surgical removal of primary tumor efficiently inhibited tumor recurrence in SC4-grafted mouse models. Collectively, these results strongly suggest that CAP should be developed as an efficient adjuvant treatment for VS after surgery to eliminate the possible remnant tumor cells, and to minimize the surgical area in the brain for post-surgical wellbeing.

Mechanistic insights into the impact of Cold Atmospheric Pressure Plasma on human epithelial cell lines

Compelling evidence suggests that Cold Atmospheric Pressure Plasma (CAPP) has potential as a new cancer therapy. However, knowledge about cellular signaling events and toxicity subsequent to plasma treatment is still poorly documented. The aim of this study was to focus on the interaction between 3 different types of plasma (He, He-O2, He-N2) and human epithelial cell lines to gain better insight into plasma-cell interaction. We provide evidence that reactive oxygen and nitrogen species (RONS) are inducing cell death by apoptosis and that the proteasome, a major intracellular proteolytic system which is important for tumor cell growth and survival, is a target of (He or He-N2) CAPP. However, RONS are not the only actors involved in cell death; electric field and charged particles could play a significant role especially for He-O2 CAPP. By differential label-free quantitative proteomic analysis we found that CAPP triggers antioxidant and cellular defense but is also affecting extracellular matrix in keratinocytes. Moreover, we found that malignant cells are more resistant to CAPP treatment than normal cells. Taken together, our findings provide insight into potential mechanisms of CAPP-induced proteasome inactivation and the cellular consequences of these events.

Fluorescence microscopic analysis of antifungal effects of cold atmospheric pressure plasma in Saccharomyces cerevisiae.

Cold atmospheric pressure plasma (CAP) has potential to be utilized as an alternative method for sterilization in food industries without thermal damage or toxic residues. In contrast to the bactericidal effects of CAP, information regarding the efficacy of CAP against eukaryotic microorganisms is very limited. Therefore, herein we investigated the effects of CAP on the budding yeast Saccharomyces cerevisiae, with a focus on the cellular response to CAP. The CAP treatment caused oxidative stress responses including the nuclear accumulation of the oxidative stress responsive transcription factor Yap1, mitochondrial fragmentation, and enhanced intracellular oxidation. Yeast cells also induced the expression of heat shock protein (HSP) genes and formation of Hsp104 aggregates when treated with CAP, suggesting that CAP denatures proteins. As phenomena unique to eukaryotic cells, the formation of cytoplasmic mRNP granules such as processing bodies and stress granules and changes in the intracellular localization of Ire1 were caused by the treatment with CAP, indicating that translational repression and endoplasmic reticulum (ER) stress were induced by the CAP treatment. These results suggest that the fungicidal effects of CAP are attributed to the multiple severe stresses.

First insights on plasma orthodontics - Application of cold atmospheric pressure plasma to enhance the bond strength of orthodontic brackets

ObjectiveThe development of an ideal adhesive system has long been subject of research. Recent studies show that treatment with cold atmospheric pressure plasma (CAP) positively affects the bonding properties of enamel. Conditioning with CAP could therefore improve the mechanical and physical properties of bracket adhesives, e.g. Glass ionomer cement (GIC). Material and methodsLaser-structured brackets (Dentaurum, Ispringen) were bonded onto 60 bovine mandibular incisors using different orthodontic adhesives. For 20 specimens FujiOrthoLC (GC America Corp, Alsip, USA) was used according to manufacturer's instructions. Another 20 specimens received a 60s CAP-treatment (kINPen med, Neoplas tool, Greifswald, Germany) before bracket bonding, of which 10 were re-moistened before applying FujiOrthoLC and 10 remained dry. Onto 20 specimens, brackets were bonded with the Composite Transbond XT (3M/Unitek, St. Paul, USA) following manufacturer's instructions. The shear bond strength of brackets on the teeth was determined with the universal testing machine Zwick BZ050/TH3A (Zwick, Ulm, Germany). ResultsBrackets bonded with FujiOrthoLC in standard method, showed average shear bond strength of 5.58±0.46MPa. Specimens treated with plasma showed clinically unacceptable adhesion values (re-moistened group: 2.79±0.38MPa, dry group: 1.01±0.2MPa). Bonding onto dried out teeth also led to spontaneous bracket losses (4 of 10 specimens). The composite group (Transbond XT) showed clinically acceptable adhesion values (7.9±1.03MPa). ConclusionsDespite promising potential, surface conditioning with CAP could not improve the adhesive properties of GIC. By contrast, a decrease in shear bond strength was noticed after CAP treatment. Further investigations have to show whether it is possible to increase the retention values ​​of other orthodontic adhesives by CAP application and thus take advantage of positive characteristics and reduce side effects.

Cold atmospheric pressure plasma processing of insect flour from Tenebrio molitor: Impact on microbial load and quality attributes in comparison to dry heat treatment

Abstract In this study, the applicability of semi-direct cold atmospheric pressure plasma (CAPP) during postharvest processing of Tenebrio molitor flour is investigated. Besides analyzing the decontamination efficacy, plasma-induced impact on techno-functionality, protein solubility, composition and structure was determined and compared to heat induced effects. Following CAPP treatment, the total microbial load of the Tenebrio flour of 7.72 log10 cfu/g was reduced to 7.10 (1 min), 6.72 (2.5 min), 5.79 (5 min), 5.19 (7.5 min), 5.21 (10 min) and 4.73 (15 min) log10 cfu/g. With increasing exposure to CAPP, protein solubility at pH 4 almost linearly decreased to a minimum of 54%. Water binding capacity decreased from 0.79 to 0.64 gwater/g whereas oil binding capacity increased from 0.59 to 0.66 goil/g. Gel electrophoresis revealed a decrease of all protein fractions at pH 4 whereas at pH 10 the band pattern significantly shifted to protein fractions with higher molecular weights. Industrial relevance Edible insects are rich in valuable protein, fat, fibre, minerals and micronutrients. Although a wide range of species represent a valuable alternative protein source that could contribute to food and feed security, they are industrially hardly exploited. The tailored application of proper processing technologies could lead to novel insect-based high-protein food and feed products with unique functional properties supporting the increase in acceptability among potential consumers. Current research concentrates on developing processing chains including innovative nonthermal approaches. Cold atmospheric pressure plasma (CAPP) has gained attention as an effective technology for the decontamination and modification of fresh and dry agricultural products. In the postharvest chain of edible insects, the application of CAPP could contribute to the development of safe and high-quality insect-based products in the food and feed sector.

Cold atmospheric pressure (CAP) plasma assisted tailoring of LDPE film surfaces for enhancement of adhesive and cytocompatible properties: Influence of operating parameters

Low density polyethylene (LDPE) plays a vital role in tissue engineering application because of its superior bulk properties. However, the cell affinity is one of the significant factors in determining the cell compatibility of polymers which depends on the surface properties such as hydrophilicity, surface chemistry and morphology. Due to intrinsic poor surface properties, the cell affinity is one of the major deterrents of LDPE films in biomedical applications. Hence, in the present investigation we discuss the influence of operating parameters such as applied potential, exposure time and type of plasma processing gases on the improvement of surface and cell compatible properties of the LDPE film using cold atmospheric pressure (CAP) plasma. The surface chemistry and hydrophilicity of the LDPE films were examined using X-ray photoelectron spectroscopy (XPS), contact angle (CA) respectively. Further, surface energy (SE) of the LDPE films were estimated from CA data by Fowke's approximation method. The quantification of topographical changes on the surface of LDPE films was carried out by atomic force microscopy (AFM). Adhesive strength of the surface modified films was analyzed by T-peel and lap shear tests. Finally, in vitro cytocompatibility studies of the surface modified LDPE films were carried out using NIH3T3 (mouse embryonic fibroblast) cells. The results obtained from various characterization techniques evidently revealed that CAP plasma treatment enhanced the surface properties (hydrophilicity, surface morphology and surface chemistry) of the LDPE films. These physico-chemical changes induced by the CAP plasma treatment facilitates the improvement in adhesive strength as well as adhesion and proliferation of cells on the surface of LDPE films.

Effect of cold atmospheric pressure plasma gas composition on the surface and cyto-compatible properties of low density polyethylene (LDPE) films

In the present investigation, we have studied the influence of oxygen (O2) flow rate in the atmospheric pressure argon (Ar) plasma zone for improvement of the surface and cell compatible properties of LDPE film. Various characterization techniques such as contact angle (CA), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), etc were used to investigate the hydrophilicity, surface chemistry and morphology of LDPE films respectively. Fowke's approximation method was used to evaluate the polar and dispersion components of the total surface energy of LDPE films using contact angle values of three testing liquids. Moreover T-peel and lap shear tests were used to analyze the adhesive strength of the surface modified LDPE films. Finally cyto-compatibility of the surface modified LDPE film was analyzed by in vitro cell compatibility analysis which includes the cell viability and adhesion using NIH-3T3 fibroblast cells. The results obtained from various characterization techniques evidently revealed that cold atmospheric pressure (CAP) plasma treatment enhanced the surface properties (hydrophilicity, surface morphology and surface chemistry) of LDPE film. Owing to tailored physico-chemical changes induced by the CAP plasma treatment facilitates improvement in adhesive strength as well as adhesion and proliferation of cells on the surface of LDPE films.

Selective Killing Effects of Cold Atmospheric Pressure Plasma with NO Induced Dysfunction of Epidermal Growth Factor Receptor in Oral Squamous Cell Carcinoma.

The aim of this study is to investigate the effects of cold atmospheric pressure plasma (CAP)-induced radicals on the epidermal growth factor receptor (EGFR), which is overexpressed by oral squamous cell carcinoma, to determine the underlying mechanism of selective killing. CAP-induced highly reactive radicals were observed in both plasma plume and cell culture media. The selective killing effect was observed in oral squamous cell carcinoma compared with normal human gingival fibroblast. Degradation and dysfunction of EGFRs were observed only in the EGFR-overexpressing oral squamous cell carcinoma and not in the normal cell. Nitric oxide scavenger pretreatment in cell culture media before CAP treatment rescued above degradation and dysfunction of the EGFR as well as the killing effect in oral squamous cell carcinoma. CAP may be a promising cancer treatment method by inducing EGFR dysfunction in EGFR-overexpressing oral squamous cell carcinoma via nitric oxide radicals.

Effect of Cold Atmospheric Pressure Plasma on the Wheat Seedlings Vigor and on the Inactivation of Microorganisms on the Seeds Surface

Effects of a cold atmospheric pressure plasma (CAPP) treatment on the germination, production of biomass, vigor of seedlings, uptake of water of wheat seeds (Triticum aestivum L. cv. Eva) were investigated. The CAPP treatment influence on the inactivation of microorganisms occurring on the surface of wheat seeds was investigated also. The so-called Diffuse Coplanar Surface Barrier Discharge generating a cold plasma in ambient air with high power volume density of some 100 W/cm3 was used for the treatment of seeds at exposure times in the range of 10–600 s. The optical emission spectroscopy and the electrical measurements were used for estimation of CAPP parameters. The obtained results indicate that the germination rate, dry weight and vigor of seedlings significantly increased for plasma treatment from 20 to 50 s. The plasma treatment of seeds led to an extensive increase in wettability and faster germination comparing with the untreated seeds. The growth inhibition effect of CAPP on the surface microflora of wheat seeds increased with the increase of the treatment time. The efficiency of the treatment of wheat seeds artificially contaminated with pure cultures of filamentous fungi decreased in the following order: Fusarium nivale > F. culmorum > Trichothecium roseum > Aspergillus flavus > A. clavatus.

Synergistic Inhibition of Tumor Cell Proliferation by Cold Plasma and Gemcitabine

In the field of plasma medicine, cold atmospheric pressure plasma (CAP) is applied to biological matter for a therapeutic benefit. The latter is mediated by CAP‐generated reactive species which treatment time‐dependently either stimulate cells or induce their apoptosis. Accordingly, antitumor effects of plasma have been observed previously, but only few studies have included proper controls to compare the plasma's cytotoxicity. We here present results that murine cancer cells are more susceptible to CAP treatment compared to non‐malignant fibroblasts in vitro. Additional challenge with the chemotherapeutic Gemcitabine significantly enhanced tumor cell but not fibroblast metabolic inhibition, suggesting potential combinatory effects in anticancer therapy.

Flow cytometric evaluation of physico-chemical impact on Gram-positive and Gram-negative bacteria.

Since heat sensitivity of fruits and vegetables limits the application of thermal inactivation processes, new emerging inactivation technologies have to be established to fulfill the requirements of food safety without affecting the produce quality. The efficiency of inactivation treatments has to be ensured and monitored. Monitoring of inactivation effects is commonly performed using traditional cultivation methods which have the disadvantage of the time span needed to obtain results. The aim of this study was to compare the inactivation effects of peracetic acid (PAA), ozonated water (O3), and cold atmospheric pressure plasma (CAPP) on Gram-positive and Gram-negative bacteria using flow cytometric methods. E. coli cells were completely depolarized after treatment (15 s) with 0.25% PAA at 10°C, and after treatment (10 s) with 3.8 mg l−1 O3 at 12°C. The membrane potential of CAPP treated cells remained almost constant at an operating power of 20 W over a time period of 3 min, and subsequently decreased within 30 s of further treatment. Complete membrane permeabilization was observed after 10 s O3 treatment, but treatment with PAA and CAPP did not completely permeabilize the cells within 2 and 4 min, respectively. Similar results were obtained for esterase activity. O3 inactivates cellular esterase but esterase activity was detected after 4 min CAPP treatment and 2 min PAA treatment. L. innocua cells and P. carotovorum cells were also permeabilized instantaneously by O3 treatment at concentrations of 3.8 ± 1 mg l−1. However, higher membrane permeabilization of L. innocua and P. carotovorum than of E. coli was observed at CAPP treatment of 20 W. The degree of bacterial damage due to the inactivation processes is highly dependent on treatment parameters as well as on treated bacteria. Important information regarding the inactivation mechanisms can be obtained by flow cytometric measurements and this enables the definition of critical process parameters.

Impact of surface structure and feed gas composition on Bacillus subtilis endospore inactivation during direct plasma treatment.

This study investigated the inactivation efficiency of cold atmospheric pressure plasma treatment on Bacillus subtilis endospores dependent on the used feed gas composition and on the surface, the endospores were attached on. Glass petri-dishes, glass beads, and peppercorns were inoculated with the same endospore density and treated with a radio frequency plasma jet. Generated reactive species were detected using optical emission spectroscopy. A quantitative polymerase chain reaction (qPCR) based ratio detection system was established to monitor the DNA damage during the plasma treatment. Argon + 0.135% vol. oxygen + 0.2% vol. nitrogen as feed gas emitted the highest amounts of UV-C photons and considerable amount of reactive oxygen and nitrogen species. Plasma generated with argon + 0.135% vol. oxygen was characterized by the highest emission of reactive oxygen species (ROS), whereas the UV-C emission was negligible. The use of pure argon showed a negligible emission of UV photons and atomic oxygen, however, the emission of vacuum (V)UV photons was assumed. Similar maximum inactivation results were achieved for the three feed gas compositions. The surface structure had a significant impact on the inactivation efficiency of the plasma treatment. The maximum inactivation achieved was between 2.4 and 2.8 log10 on glass petri-dishes and 3.9 to 4.6 log10 on glass beads. The treatment of peppercorns resulted in an inactivation lower than 1.0 log10. qPCR results showed a significant DNA damage for all gas compositions. Pure argon showed the highest results for the DNA damage ratio values, followed by argon + 0.135% vol. oxygen + 0.2% vol. nitrogen. In case of argon + 0.135% vol. oxygen the inactivation seems to be dominated by the action of ROS. These findings indicate the significant role of VUV and UV photons in the inactivation process of B. subtilis endospores.

On the history of plasma treatment and comparison of microbiostatic efficacy of a historical high-frequency plasma device with two modern devices.

Background: Cold atmospheric pressure plasma (CAP) with its many bioactive properties has defined a new medical field: the plasma medicine. However, in the related form of high-frequency therapy, CAP was even used briefly a century ago. The aim of this study was to review historic CAP treatments and to obtain data regarding the antimicrobial efficacy of a historical high-frequency plasma device.Methods: First, historic literature regarding the history of CAP treatment was evaluated, because in the modern literature no data were available. Second, the susceptibility of 5 different bacterial wound isolates, cultured on agar, to a historic plasma source (violet wand [VW]) and two modern devices (atmospheric pressure plasma jet [APPJ] and Dielectric Barrier Discharge [DBD]) was analyzed . The obtained inhibition areas (IA) were compared.Results: First, the most convenient popular historical electromedical treatments produced a so-called effluvia by using glass electrodes, related to today’s CAP. Second, all three tested plasma sources showed complete eradication of all tested microbial strains in the treated area. The “historical” cold VW plasma showed antimicrobial effects similar to those of modern APPJ and DBD regarding the diameter of the IA.Conclusion: Some retrograde evidence may be deducted from this, especially for treatment of infectious diseases with historical plasma devices. The underlying technology may serve as model for construction of modern sucessive devices.

Impact of thermal treatment versus cold atmospheric plasma processing on the techno-functional protein properties from Pisum sativum ‘Salamanca’

This study aimed at evaluating the potential of cold atmospheric pressure plasma (CAPP) treatment for the functionalization of dry bulky and powdery food materials. CAPP treatment was capable of modifying protein and techno-functional properties of different flour fractions from grain pea (Pisum sativum ‘Salamanca’). Experiments using a pea protein isolate indicated that the reason for the increase in water and fat binding capacities in protein rich pea flour to 113% and 116%, respectively, is based on plasma-induced modifications of the proteins as their solubility was increased to 191%. This is also supported by detected changes in tryptophan fluorescence spectra. With increasing treatment times the fluorescence emission intensity increased at 328nm and decreased at 355nm indicating structural and/or compositional changes of the proteins. The results indicate that the application of CAPP can be exploited as a means to modulate functionality of dry bulk materials in the food sector.

Impact of cold atmospheric pressure plasma on physiology and flavonol glycoside profile of peas (Pisum sativum ‘Salamanca’)

Application of plasma is well-established in various industrial processes; its use has also been suggested as an innovative technology in the food sector. Besides the ability to inactivate undesirable microorganisms on heat-sensitive foods, cold atmospheric pressure plasma (CAPP) may also modify and intensify the secondary metabolism in agricultural plant produces along the whole value-added chain. This is because CAPP provides a source of reactive oxygen and nitrogen species and specific UV radiation.The objective of this study was to determine the effects of CAPP treatment on the flavonol glycoside profile of pea seedlings (Pisum sativum ‘Salamanca’), while considering the potential impact on their metabolic activity in different growth stages. Pea seeds, sprouts, and seedlings were exposed to semi-direct CAPP using a dielectric barrier discharge device with air as the process gas. Applying voltages between 6 and 12kVpp at a frequency of 3.0kHz resulted in optical emission spectra dominated by UV-B and UV-C radiation. The specific energy densities were monitored upon varying voltages and treatment times.Exposing swollen pea seeds to plasma (9kVpp) between 1 and 10min increased germination rate and dry matter content but decreased growth rate. Non-acylated and monoacylated triglycosides of quercetin and kaempferol dominated the flavonol glycoside profile, quercetin-3-O-p-coumaroyl-triglucoside being the main flavonoid glycoside. In 15d-old pea seedlings, the concentration of flavonoid glycosides was dose-dependently decreased after two CAPP treatments compared to none or three treatments. Furthermore, photosynthetic efficiency of treated pea sprouts and seedlings declined potentially indicating a negative effect of CAPP treatment on plant metabolism. The responses of pea tissues greatly depended on time point and duration of CAPP treatments. This study represents a first step towards the implementation of the CAPP technology for a targeted modification of valuable secondary plant metabolites during post-harvest chain of agricultural produces.

Head and neck cancer treatment and physical plasma

This study is a retrospective review of representing clinical follow-up of 12 patients afflicted with advanced squamous cell carcinoma of the head and neck. Herein, we have used novel physical cold atmospheric pressure plasma (CAP) to decontaminate infected cancer ulcerations and evaluated anti-cancer effects. With use of CAP in this cohort, the data suggests: (1) decreased request for pain medication and (2) reduction of typical fetid odor related to (3) reduction of microbial load. In some cases there is (4) superficial partial remission of tumor and even (5) wound healing of infected ulcerations has been observed following CAP exposure. As a result, CAP treatment appears of benefit for select head and neck cancer patients and future work to optimize CAP in the therapeutic armamentarium advances.

Evidence for a radial strain gradient in apple fruit cuticles.

The morphological outer side of the apple fruit cuticle is markedly more strained than the inner side. This strain is released upon wax extraction. This paper investigates the effect of ablating outer and inner surfaces of isolated cuticular membranes (CM) of mature apple (Malus × domestica) fruit using cold atmospheric pressure plasma (CAPP) on the release of strain after extraction of waxes. Strain release was quantified as the decrease in area of CM discs following CAPP treatment and subsequent solvent extraction of wax. Increasing duration of CAPP treatment proportionally decreased CM mass per unit area. There was no difference in mass loss rate between CAPP treatments of outer or inner surfaces. Also, there was no difference in surface area of CMs before and after CAPP treatment. However, upon subsequent wax extraction, surface area of CMs decreased indicating the release of strain. Increasing the duration of CAPP treatment resulted in increasing strain release up to 47.7 ± 8.0 % at 20 min when CAPP was applied to the inner surface. In contrast, strain release was independent of CAPP duration averaging about 12.1 ± 0.6 % when applied to the outer surface of the CM. Our results provide evidence for a marked gradient of strain between the outer side (strained) and the inner side of the CM (not strained) of mature apple fruit.