Search Results
Microwave plasma discharges for biomass pretreatment: Degradation of a sodium carboxymethyl cellulose model
2020, Honnorat, B., Brüser, V., Kolb, J.F.
Biogas production is an important component of an environmentally benign renewable energy strategy. However, the cost-effectiveness of biogas production from biomass is limited by the presence of polymeric structures, which are recalcitrant to digestion by bacteria. Therefore, pretreatments must often be applied prior to anaerobic fermentation to increase yields of biogas. Many physico-chemical pretreatments have a high energy demand and are generally costly. An alternative could be the ignition of a plasma directly in the biomass substrate. The reactive species that are generated by plasma-liquid interactions, such as hydroxyl radicals and hydrogen peroxides, could contribute significantly to the disintegration of cell walls and the breakage of poorly digestible polymers. With respect to economic, processing, and other potential benefits, a microwave instigated and sustained plasma was investigated. A microwave circuit transmitted 2-kW pulses into a recirculated sodium carboxymethyl cellulose solution, which mimicked the rheological properties of biomass. Each microwave pulse had a duration of 12.5 ms and caused the ignition of a discharge after a vapor bubble had formed. Microwaves were absorbed in the process with an efficiency of ∼97%. Slow-motion imaging showed the development of the discharge. The plasma discharges provoked a decrease in the viscosity, probably caused by the shortening of polymer chains of the cellulose derivative. The decrease in viscosity by itself could reduce processing costs and promotes bacterial activity in actual biomass. The results demonstrate the potential of microwave in-liquid plasma discharges for the pretreatment of biomass. © 2020 Author(s).
On the liquid chemistry of the reactive nitrogen species peroxynitrite and nitrogen dioxide generated by physical plasmas
2020, Bruno, Giuliana, Wenske, Sebastian, Lackmann, Jan-Wilm, Lalk, Michael, Von Woedtke, Thomas, Wende, Kristian
Cold physical plasmas modulate cellular redox signaling processes, leading to the evolution of a number of clinical applications in recent years. They are a source of small reactive species, including reactive nitrogen species (RNS). Wound healing is a major application and, as its physiology involves RNS signaling, a correlation between clinical effectiveness and the activity of plasma‐derived RNS seems evident. To investigate the type and reactivity of plasma‐derived RNS in aqueous systems, a model with tyrosine as a tracer was utilized. By high‐resolution mass spectrometry, 26 different tyrosine derivatives including the physiologic nitrotyrosine were identified. The product pattern was distinctive in terms of plasma parameters, especially gas phase composition. By scavenger experiments and isotopic labelling, gaseous nitric dioxide radicals and liquid phase peroxynitrite ions were determined as dominant RNS. The presence of water molecules in the active plasma favored the generation of peroxynitrite. A pilot study, identifying RNS driven post‐translational modifications of proteins in healing human wounds after the treatment with cold plasma (kINPen), demonstrated the presence of in vitro determined chemical pathways. The plasma‐driven nitration and nitrosylation of tyrosine allows the conclusion that covalent modification of biomolecules by RNS contributes to the clinically observed impact of cold plasmas. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
Nonspherical Nanoparticle Shape Stability Is Affected by Complex Manufacturing Aspects: Its Implications for Drug Delivery and Targeting
2019, Haryadi, Bernard Manuel, Hafner, Daniel, Amin, Ihsan, Schubel, Rene, Jordan, Rainer, Winter, Gerhard, Engert, Julia
The shape of nanoparticles is known recently as an important design parameter influencing considerably the fate of nanoparticles with and in biological systems. Several manufacturing techniques to generate nonspherical nanoparticles as well as studies on in vitro and in vivo effects thereof have been described. However, nonspherical nanoparticle shape stability in physiological-related conditions and the impact of formulation parameters on nonspherical nanoparticle resistance still need to be investigated. To address these issues, different nanoparticle fabrication methods using biodegradable polymers are explored to produce nonspherical nanoparticles via the prevailing film-stretching method. In addition, systematic comparisons to other nanoparticle systems prepared by different manufacturing techniques and less biodegradable materials (but still commonly utilized for drug delivery and targeting) are conducted. The study evinces that the strong interplay from multiple nanoparticle properties (i.e., internal structure, Young's modulus, surface roughness, liquefaction temperature [glass transition (Tg) or melting (Tm)], porosity, and surface hydrophobicity) is present. It is not possible to predict the nonsphericity longevity by merely one or two factor(s). The most influential features in preserving the nonsphericity of nanoparticles are existence of internal structure and low surface hydrophobicity (i.e., surface-free energy (SFE) > ≈55 mN m−1, material–water interfacial tension <6 mN m−1), especially if the nanoparticles are soft (<1 GPa), rough (Rrms > 10 nm), porous (>1 m2 g−1), and in possession of low bulk liquefaction temperature (<100 °C). Interestingly, low surface hydrophobicity of nanoparticles can be obtained indirectly by the significant presence of residual stabilizers. Therefore, it is strongly suggested that nonsphericity of particle systems is highly dependent on surface chemistry but cannot be appraised separately from other factors. These results and reviews allot valuable guidelines for the design and manufacturing of nonspherical nanoparticles having adequate shape stability, thereby appropriate with their usage purposes. Furthermore, they can assist in understanding and explaining the possible mechanisms of nonspherical nanoparticles effectivity loss and distinctive material behavior at the nanoscale. © 2019 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Identification of two kinase inhibitors with synergistic toxicity with low-dose hydrogen peroxide in colorectal cancer cells in vitro
2020, Freund, Eric, Liedtke, Kim-Rouven, Miebach, Lea, Wende, Kristian, Heidecke, Amanda, Kaushik, Nagendra Kumar, Choi, Eun Ha, Partecke, Lars-Ivo, Bekeschus, Sander
Colorectal carcinoma is among the most common types of cancers. With this disease, diffuse scattering in the abdominal area (peritoneal carcinosis) often occurs before diagnosis, making surgical removal of the entire malignant tissue impossible due to a large number of tumor nodules. Previous treatment options include radiation and its combination with intraperitoneal heat-induced chemotherapy (HIPEC). Both options have strong side effects and are often poor in therapeutic efficacy. Tumor cells often grow and proliferate dysregulated, with enzymes of the protein kinase family often playing a crucial role. The present study investigated whether a combination of protein kinase inhibitors and low-dose induction of oxidative stress (using hydrogen peroxide, H2O2) has an additive cytotoxic effect on murine, colorectal tumor cells (CT26). Protein kinase inhibitors from a library of 80 substances were used to investigate colorectal cancer cells for their activity, morphology, and immunogenicity (immunogenic cancer cell death, ICD) upon mono or combination. Toxic compounds identified in 2D cultures were confirmed in 3D cultures, and additive cytotoxicity was identified for the substances lavendustin A, GF109203X, and rapamycin. Toxicity was concomitant with cell cycle arrest, but except HMGB1, no increased expression of immunogenic markers was identified with the combination treatment. The results were validated for GF109203X and rapamycin but not lavendustin A in the 3D model of different colorectal (HT29, SW480) and pancreatic cancer cell lines (MiaPaca, Panc01). In conclusion, our in vitro data suggest that combining oxidative stress with chemotherapy would be conceivable to enhance antitumor efficacy in HIPEC. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.
The equivalent circuit approach for the electrical diagnostics of dielectric barrier discharges: The classical theory and recent developments
2019, Pipa, Andrei V., Brandenburg, Ronny
Measurements of current and voltage are the basic diagnostics for electrical discharges. However, in the case of dielectric barrier discharges (DBDs), the measured current and voltage waveforms are influenced by the discharge reactor geometry, and thus, interpretation of measured quantities is required to determine the discharge properties. This contribution presents the main stages of the development of electrical diagnostics of DBDs, which are based on lumped electrical elements. The compilation and revision of the contributions to the equivalent circuit approach are targeted to indicate: (1) the interconnection between the stage of development, (2) its applicability, and (3) the current state-of-the-art of this approach. © 2019 by the authors.
Nonenzymatic post-translational modifications in peptides by cold plasma-derived reactive oxygen and nitrogen species
2020, Wenske, Sebastian, Lackmann, Jan-Wilm, Bekeschus, Sander, Weltmann, Klaus-Dieter, Von Woedtke, Thomas, Wende, Kristian
Cold physical plasmas are emerging tools for wound care and cancer control that deliver reactive oxygen species (ROS) and nitrogen species (RNS). Alongside direct effects on cellular signaling processes, covalent modification of biomolecules may contribute to the observed physiological consequences. The potential of ROS/RNS generated by two different plasma sources (kINPen and COST-Jet) to introduce post-translational modifications (PTMs) in the peptides angiotensin and bradykinin was explored. While the peptide backbone was kept intact, a significant introduction of oxidative PTMs was observed. The modifications cluster at aromatic (tyrosine, histidine, and phenylalanine) and neutral amino acids (isoleucine and proline) with the introduction of one, two, or three oxygen atoms, ring cleavages of histidine and tryptophan, and nitration/nitrosylation predominantly observed. Alkaline and acidic amino acid (arginine and aspartic acid) residues showed a high resilience, indicating that local charges and the chemical environment at large modulate the attack of the electron-rich ROS/RNS. Previously published simulations, which include only OH radicals as ROS, do not match the experimental results in full, suggesting the contribution of other short-lived species, i.e., atomic oxygen, singlet oxygen, and peroxynitrite. The observed PTMs are relevant for the biological activity of peptides and proteins, changing polarity, folding, and function. In conclusion, it can be assumed that an introduction of covalent oxidative modifications at the amino acid chain level occurs during a plasma treatment. The introduced changes, in part, mimic naturally occurring patterns that can be interpreted by the cell, and subsequently, these PTMs allow for prolonged secondary effects on cell physiology. © 2020 Author(s).
On the relationship between SiF4plasma species and sample properties in ultra low-k etching processes
2020, Haase, Micha, Melzer, Marcel, Lang, Norbert, Ecke, Ramona, Zimmermann, Sven, van Helden, Jean-Pierre H., Schulz, Stefan E.
The temporal behavior of the molecular etching product SiF4 in fluorocarbon-based plasmas used for the dry etching of ultra low-k (ULK) materials has been brought into connection with the polymer deposition on the surface during plasma treatment within the scope of this work. For this purpose, time-resolved measurements of the density of SiF4 have been performed by quantum cascade laser absorption spectroscopy. A quantification of the non-linear time dependence was achieved by its characterization via a time constant of the decreasing SiF4 density over the process time. The time constant predicts how fast the stationary SiF4 density is reached. The higher the time constant is, the thicker the polymer film on top of the treated ultra low-k surface. A correlation between the time constant and the ULK damage was also found. ULK damage and polymer deposition were proven by Variable Angle Spectroscopic Ellipsometry and X-ray Photoelectron Spectroscopy. In summary, the observed decay of the etching product concentration over process time is caused by the suppressed desorption of the SiF4 molecules due to a more dominant adsorption of polymers. © 2020 Author(s).
Cold atmospheric plasma is a potent tool to improve chemotherapy in melanoma in vitro and in vivo
2020, Alimohammadi, Mina, Golpour, Monireh, Sohbatzadeh, Farshad, Hadavi, Seyedehniaz, Bekeschus, Sander, Niaki, Haleh Akhavan, Valadan, Reza, Rafiei, Alireza
Malignant melanoma is a devastating disease. Because of its aggressiveness, it also serves as a model tumor for investigating novel therapeutic avenues. In recent years, scientific evidence has shown that cold atmospheric plasma (CAP) might be a promising modality in cancer therapy. In this study, we aimed to evaluate the effect of CAP generated by an argon plasma jet alone or in combination with dacarbazine (DAC) on melanoma cells in vitro and in vivo. The effects of the CAP on inducing lipid peroxidation and nitric oxide production were higher in B16 melanoma cells in comparison to non-malignant L929 cells. Assays on cell growth, apoptosis, and expression of genes related to, e.g., autophagic processes, showed CAP to have a substantial impact in melanoma cells while there were only minoreffects in L929 cells. In vivo, both CAP monotherapy and combination with DAC significantly decreased tumor growth. These results suggest that CAP not only selectively induces cell death in melanoma but also holds promises in combination with chemotherapy that might lead to improved tumor control. © 2020 by the authors.
Starch and Glycogen Analyses : Methods and Techniques
2020, Brust, Henrike, Orzechowski, Slawomir, Fettke, Joerg
For complex carbohydrates, such as glycogen and starch, various analytical methods and techniques exist allowing the detailed characterization of these storage carbohydrates. In this article, we give a brief overview of the most frequently used methods, techniques, and results. Furthermore, we give insights in the isolation, purification, and fragmentation of both starch and glycogen. An overview of the different structural levels of the glucans is given and the corresponding analytical techniques are discussed. Moreover, future perspectives of the analytical needs and the challenges of the currently developing scientific questions are included.
Plasma treatment limits cutaneous squamous cell carcinoma development in vitro and in vivo
2020, Pasqual-Melo, Gabriella, Nascimento, Thiago, Sanches, Larissa Juliani, Blegniski, Fernanda Paschoal, Bianchi, Julya Karen, Sagwal, Sanjeev Kumar, Berner, Julia, Schmidt, Anke, Emmert, Steffen, Weltmann, Klaus-Dieter, Woedtke, Thomas von, Gandhirajan, Rajesh Kumar, Cecchini, Alessandra Lourenço, Bekeschus, Sander
Cutaneous squamous cell carcinoma (SCC) is the most prevalent cancer worldwide, increasing the cost of healthcare services and with a high rate of morbidity. Its etiology is linked to chronic ultraviolet (UV) exposure that leads to malignant transformation of keratinocytes. Invasive growth and metastasis are severe consequences of this process. Therapy-resistant and highly aggressive SCC is frequently fatal, exemplifying the need for novel treatment strategies. Cold physical plasma is a partially ionized gas, expelling therapeutic doses of reactive oxygen and nitrogen species that were investigated for their anticancer capacity against SCC in vitro and SCC-like lesions in vivo. Using the kINPen argon plasma jet, a selective growth-reducing action of plasma treatment was identified in two SCC cell lines in 2D and 3D cultures. In vivo, plasma treatment limited the progression of UVB-induced SSC-like skin lesions and dermal degeneration without compromising lesional or non-lesional skin. In lesional tissue, this was associated with a decrease in cell proliferation and the antioxidant transcription factor Nrf2 following plasma treatment, while catalase expression was increased. Analysis of skin adjacent to the lesions and determination of global antioxidant parameters confirmed the local but not systemic action of the plasma anticancer therapy in vivo. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.