Degradation of glyphosate in water by the application of surface corona discharges

Glyphosate (GLP) is one of the most widely applied herbicides, and is found ubiquitously in the environment. The removal of glyphosate from waste water and soil is challenging and can be achieved with chemical or biological methods, which, nevertheless, suffer from different disadvantages. The application of a physical plasma for the removal of GLP in water was examined by the application of surface corona discharges in a wire-to-cylinder setup filled with argon. The plasma was ignited at the liquid surface without any additives. By applying a photometric method, GLP was detected after derivatisation with fluorenyl methoxycarbonyl chloride, whereas phosphate was determined with ammonium molybdate. A GLP degradation rate of 90.8% could be achieved within a treatment time of 30 minutes with an estimated energy efficiency of 0.32 g/kWh

Extraction of bioactive primary and secondary Metabolites from Microalgae by atmospheric pressure Plasmas and pulsed Discharges in Water

Microalgae are aquatic, unicellular, eukaryotic organisms, which perform photosynthesis. They have gained interest within the last decades not only for biofuel production due to their high amount of lipids, but also for pharmaceutical and for nutraceutical purposes. Interesting compounds are proteins, carbohydrates, or pigments, such as carotenoids. However, microalgae possess strong and rigid cell walls, which hinder a sufficient and yet, gentle extraction of those valuable compounds. Although standard extraction techniques are available, several shortcomings occur, e.g. high energy demand, use of environmentally harmful solvents or alteration of compounds due to heat or chemicals. Therefore, an alternative method is needed, which is able to address these disadvantages. Physical plasmas were thus studied to answer the question whether they are able to disintegrate the cell walls of microalgae effectively and yet, without degradation of the extractives. First step of the thesis was to find a suitable plasma source that has an effect on the cell walls because plasma effects, such as electric fields, shockwaves, UV light emission, and the generation of reactive species can be tailored with the respective setup. It was found that spark discharges are most effective for the extraction of Chlorella vulgaris, which was chosen as model organism. All extraction yields were compared to reference methods, whereat microwave radiation was found to be the most effective reference method and were hence, applied for comparative studies. For the next step, proteins were selected as targets to answer the question, which differences can be determined between plasms-treated and microwave-radiated proteins are observable although the extraction yields were equal. Furthermore, plasma effects, especially the effects of reactive species on the extracted proteins had to be studied. Findings indicate that heat sensitive proteins, such as photosystem-related proteins, or histones are better extractable with spark discharges than with microwave exposure and the effect of reactive species is only minor. The last step was to determine, which plasma effect is responsible for the observed cell wall disintegration. Therefore, the tensile strength of Chlorella vulgaris was determined and compared to the shockwave pressure, which is generated from the spark channel. It was proven that the shockwave pressure exceeds by far the tensile strength of the microalgae an can be thus held responsible for mechanism for cell wall rupture. In this thesis, it was found that spark discharges are a promising alternative for the extraction of valuable compounds from microalgae. The discharges are not only effective, but also gentle enough for sensitive compounds, such as proteins or pigments.Mikroalgen sind aquatische, einzellige, eukaryotische Organismen, die Photosynthese betreiben. Sie haben in den letzten Jahrzehnten nicht nur für die Herstellung von Biokraftstoffen aufgrund ihres hohen Lipidgehalts, sondern auch für pharmazeutische und diätetische Zwecke an Interesse gewonnen. Interessante Verbindungen sind Proteine, Kohlenhydrate oder Pigmente wie Carotinoide. Mikroalgen besitzen jedoch starke und starre Zellwände, die eine ausreichende und dennoch schonende Extraktion dieser wertvollen Verbindungen verhindern. Obwohl Standardextraktionstechniken verfügbar sind, treten verschiedene Mängel auf, z. B hoher Energiebedarf, Verwendung umweltschädlicher Lösungsmittel oder Veränderung der extrahierten Stoffe durch Hitze oder Chemikalien. Daher wird ein alternatives Verfahren benötigt, das diesen Nachteilen begegnen kann. Daher wurden physikalische Plasmen untersucht, um die Frage zu beantworten, ob diese in der Lage sind, die Zellwände von Mikroalgen effektiv und dennoch ohne Abbau der Extrakte aufzuschließen. Der erste Schritt der Arbeit bestand darin, eine geeignete Plasmaquelle zu finden, die sich auf die Zellwände auswirkt, da Plasmaeffekte wie elektrische Felder, Stoßwellen, UV-Lichtemission und die Erzeugung reaktiver Spezies auf den jeweiligen Aufbau abgestimmt werden können. Es wurde festgestellt, dass Funkenentladungen für die Extraktion von Chlorella vulgaris, welche als Modellalge ausgewählt wurde, am effektivsten sind. Alle Extraktionsausbeuten wurden mit Referenzmethoden verglichen, wobei sich Mikrowellenstrahlung als die effektivste Referenzmethode erwies und daher für Vergleichsstudien herangezogen wurden. Für den nächsten Schritt wurden Proteine als Zielsubstanzen ausgewählt, um die Frage zu beantworten, welche Unterschiede zwischen plasmabehandelten und mikrowellenbestrahlten Proteinen bei gleichen Extraktionsausbeuten zu beobachten sind. Darüber hinaus mussten Plasmaeffekte, insbesondere die Auswirkungen reaktiver Spezies auf die extrahierten Proteine untersucht werden. Die Ergebnisse deuten darauf hin, dass wärmeempfindliche Proteine, wie z.B. photosystembezogene Proteine oder Histone mit Funkenentladungen besser extrahiert werden können als mit Mikrowellen und der Einfluss reaktiver Spezies nur gering ist. Im letzten Schritt wurde ermittelt, welcher Plasmaeffekt für den beobachteten Zellwandaufbruch verantwortlich ist. Daher wurde die Zugfestigkeit von Chlorella vulgaris bestimmt und mit dem Stoßwellendruck verglichen, der durch den Funkenkanal erzeugt wird. Es wurde nachgewiesen, dass der Stoßwellendruck die Zugfestigkeit der Mikroalgen bei weitem übersteigt und somit für den Mechanismus des erfolgreichen Zellwandbruchs verantwortlich gemacht werden kann. In dieser Arbeit wurde festgestellt, dass Funkenentladungen eine vielversprechende Alternative zur Gewinnung wertvoller Substanzen aus Mikroalgen darstellen. Die Entladungen sind nicht nur effektiv, sondern auch schonend genug für empfindliche Verbindungen wie Proteine oder Pigmente

Assessment of Phycocyanin Extraction from Cyanidium caldarium by Spark Discharges, Compared to Freeze-Thaw Cycles, Sonication, and Pulsed Electric Fields

Phycocyanin is a blue colored pigment, synthesized by several species of cyanobacteria and red algae. Besides the application as a food-colorant, the pigmented protein is of high interest as a pharmaceutically and nutritionally valuable compound. Since cyanobacteria-derived phycocyanin is thermolabile, red algae that are adapted to high temperatures are an interesting source for phycocyanin extraction. Still, the extraction of high quality phycocyanin from red algae is challenging due to the strong and rigid cell wall. Since standard techniques show low yields, alternative methods are needed. Recently, spark discharges have been shown to gently disintegrate microalgae and thereby enable the efficient extraction of susceptible proteins. In this study, the applicability of spark discharges for phycocyanin extraction from the red alga Cyanidium caldarium was investigated. The efficiency of 30 min spark discharges was compared with standard treatment protocols, such as three times repeated freeze-thaw cycles, sonication, and pulsed electric fields. Input energy for all physical methods were kept constant at 11,880 J to ensure comparability. The obtained extracts were evaluated by photometric and fluorescent spectroscopy. Highest extraction yields were achieved with sonication (53 mg/g dry weight (dw)) and disintegration by spark discharges (4 mg/g dw) while neither freeze-thawing nor pulsed electric field disintegration proved effective. The protein analysis via LC-MS of the former two extracts revealed a comparable composition of phycobiliproteins. Despite the lower total concentration of phycocyanin after application of spark discharges, the purity in the raw extract was higher in comparison to the extract attained by sonication

Compact high-voltage, low-impedance nanosecond pulse generators for biomedical applications

EI

Benzo[b]quinolizinium derivatives have a strong antimalarial activity and inhibit indoleamine dioxygenase

The heme-containing enzymes indoleamine 2,3-dioxygenase-1 (IDO-1) and IDO-2 catalyze the conversion of the essential amino acid tryptophan into kynurenine. Metabolites of the kynurenine pathway and IDO itself are involved in immunity and the pathology of several diseases, having either immunoregulatory or antimicrobial effects. IDO-1 plays a central role in the pathogenesis of cerebral malaria, which is the most severe and often fatal neurological complication of infection with Plasmodium falciparum. Mouse models are usually used to study the underlying pathophysiology. In this study, we screened a natural compound library against mouse IDO-1 and identified 8-aminobenzo[b]quinolizinium (compound 2c) to be an inhibitor of IDO-1 with potency at nanomolar concentrations (50% inhibitory concentration, 164 nM). Twenty-one structurally modified derivatives of compound 2c were synthesized for structure-activity relationship analyses. The compounds were found to be selective for IDO-1 over IDO-2. We therefore compared the roles of prominent amino acids in the catalytic mechanisms of the two isoenzymes via homology modeling, site-directed mutagenesis, and kinetic analyses. Notably, methionine 385 of IDO-2 was identified to interfere with the entrance of l-tryptophan to the active site of the enzyme, which explains the selectivity of the inhibitors. Most interestingly, several benzo[b]quinolizinium derivatives (6 compounds with 50% effective concentration values between 2.1 and 6.7 nM) were found to be highly effective against P. falciparum 3D7 blood stages in cell culture with a mechanism independent of IDO-1 inhibition. We believe that the class of compounds presented here has unique characteristics; it combines the inhibition of mammalian IDO-1 with strong antiparasitic activity, two features that offer potential for drug development

NeutrobodyPlex-monitoring SARS-CoV-2 neutralizing immune responses using nanobodies.

In light of the COVID-19 pandemic, there is an ongoing need for diagnostic tools to monitor the immune status of large patient cohorts and the effectiveness of vaccination campaigns. Here, we present 11 unique nanobodies (Nbs) specific for the SARS-CoV-2 spike receptor-binding domain (RBD), of which 8 Nbs potently inhibit the interaction of RBD with angiotensin-converting enzyme 2 (ACE2) as the major viral docking site. Following detailed epitope mapping and structural analysis, we select two inhibitory Nbs, one of which binds an epitope inside and one of which binds an epitope outside the RBD:ACE2 interface. Based on these, we generate a biparatopic nanobody (bipNb) with viral neutralization efficacy in the picomolar range. Using bipNb as a surrogate, we establish a competitive multiplex binding assay ("NeutrobodyPlex") for detailed analysis of the presence and performance of neutralizing RBD-binding antibodies in serum of convalescent or vaccinated patients. We demonstrate that NeutrobodyPlex enables high-throughput screening and detailed analysis of neutralizing immune responses in infected or vaccinated individuals, to monitor immune status or to guide vaccine design