TY - GEN A1 - Prestel, Andreas A1 - Möller, Heiko Michael T1 - Spatio-temporal control of cellular uptake achieved by photoswitchable cell-penetrating peptides N2 - The selective uptake of compounds into specific cells of interest is a major objective in cell biology and drug delivery. By incorporation of a novel, thermostable azobenzene moiety we generated peptides that can be switched optically between an inactive state and an active, cell-penetrating state with excellent spatio-temporal control. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 218 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-89658 SP - 701 EP - 704 ER - TY - GEN A1 - Guha, S. A1 - Warsinke, A. A1 - Tientcheu, Ch. M. A1 - Schmalz, K. A1 - Meliani, C. A1 - Wenger, Ch. T1 - Label free sensing of creatinine using a 6 GHz CMOS near-field dielectric immunosensor N2 - In this work we present a CMOS high frequency direct immunosensor operating at 6 GHz (C-band) for label free determination of creatinine. The sensor is fabricated in standard 0.13 μm SiGe:C BiCMOS process. The report also demonstrates the ability to immobilize creatinine molecules on a Si3N4 passivation layer of the standard BiCMOS/CMOS process, therefore, evading any further need of cumbersome post processing of the fabricated sensor chip. The sensor is based on capacitive detection of the amount of non-creatinine bound antibodies binding to an immobilized creatinine layer on the passivated sensor. The chip bound antibody amount in turn corresponds indirectly to the creatinine concentration used in the incubation phase. The determination of creatinine in the concentration range of 0.88–880 μM is successfully demonstrated in this work. A sensitivity of 35 MHz/10 fold increase in creatinine concentration (during incubation) at the centre frequency of 6 GHz is gained by the immunosensor. The results are compared with a standard optical measurement technique and the dynamic range and sensitivity is of the order of the established optical indication technique. The C-band immunosensor chip comprising an area of 0.3 mm2 reduces the sensing area considerably, therefore, requiring a sample volume as low as 2 μl. The small analyte sample volume and label free approach also reduce the experimental costs in addition to the low fabrication costs offered by the batch fabrication technique of CMOS/BiCMOS process. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 195 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-81177 ER - TY - GEN A1 - Bartoloni, Marco A1 - Jin, Xian A1 - Marcaida, Maria José A1 - Banha, Joao A1 - Dibonaventura, Ivan A1 - Bongoni, Swathi A1 - Bartho, Kathrin A1 - Gräbner, Olivia A1 - Sefkow, Michael A1 - Darbre, Tamis A1 - Reymond, Jean-Louis T1 - Bridged bicyclic peptides as potential drug scaffolds BT - synthesis, structure, protein binding and stability N2 - Double cyclization of short linear peptides obtained by solid phase peptide synthesis was used to prepare bridged bicyclic peptides (BBPs) corresponding to the topology of bridged bicyclic alkanes such as norbornane. Diastereomeric norbornapeptides were investigated by 1H-NMR, X-ray crystallography and CD spectroscopy and found to represent rigid globular scaffolds stabilized by intramolecular backbone hydrogen bonds with scaffold geometries determined by the chirality of amino acid residues and sharing structural features of β-turns and α-helices. Proteome profiling by capture compound mass spectrometry (CCMS) led to the discovery of the norbornapeptide 27c binding selectively to calmodulin as an example of a BBP protein binder. This and other BBPs showed high stability towards proteolytic degradation in serum. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 197 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-81239 ER - TY - GEN A1 - Meyer, S. A1 - Raber, G. A1 - Ebert, Franziska A1 - Leffers, L. A1 - Müller, Sandra Marie A1 - Taleshi, M. S. A1 - Francesconi, Kevin A. A1 - Schwerdtle, Tanja T1 - In vitro toxicological characterisation of arsenic-containing fatty acids and three of their metabolites N2 - Arsenic-containing fatty acids are a group of fat-soluble arsenic species (arsenolipids) which are present in marine fish and other seafood. Recently, it has been shown that arsenic-containing hydrocarbons, another group of arsenolipids, exert toxicity in similar concentrations comparable to arsenite although the toxic modes of action differ. Hence, a risk assessment of arsenolipids is urgently needed. In this study the cellular toxicity of a saturated (AsFA 362) and an unsaturated (AsFA 388) arsenic-containing fatty acid and three of their proposed metabolites (DMAV, DMAPr and thio-DMAPr) were investigated in human liver cells (HepG2). Even though both arsenic-containing fatty acids were less toxic as compared to arsenic-containing hydrocarbons and arsenite, significant effects were observable at μM concentrations. DMAV causes effects in a similar concentration range and it could be seen that it is metabolised to its highly toxic thio analogue thio-DMAV in HepG2 cells. Nevertheless, DMAPr and thio-DMAPr did not exert any cytotoxicity. In summary, our data indicate that risks to human health related to the presence of arsenic-containing fatty acids in marine food cannot be excluded. This stresses the need for a full in vitro and in vivo toxicological characterisation of these arsenolipids. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 199 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-82008 ER - TY - GEN A1 - Roder, Phillip A1 - Hille, Carsten T1 - A Multifunctional Frontloading Approach for Repeated Recycling of a Pressure-Controlled AFM Micropipette N2 - Fluid force microscopy combines the positional accuracy and force sensitivity of an atomic force microscope (AFM) with nanofluidics via a microchanneled cantilever. However, adequate loading and cleaning procedures for such AFM micropipettes are required for various application situations. Here, a new frontloading procedure is described for an AFM micropipette functioning as a force- and pressure-controlled microscale liquid dispenser. This frontloading procedure seems especially attractive when using target substances featuring high costs or low available amounts. Here, the AFM micropipette could be filled from the tip side with liquid from a previously applied droplet with a volume of only a few μL using a short low-pressure pulse. The liquid-loaded AFM micropipettes could be then applied for experiments in air or liquid environments. AFM micropipette frontloading was evaluated with the well-known organic fluorescent dye rhodamine 6G and the AlexaFluor647-labeled antibody goat anti-rat IgG as an example of a larger biological compound. After micropipette usage, specific cleaning procedures were tested. Furthermore, a storage method is described, at which the AFM micropipettes could be stored for a few hours up to several days without drying out or clogging of the microchannel. In summary, the rapid, versatile and cost-efficient frontloading and cleaning procedure for the repeated usage of a single AFM micropipette is beneficial for various application situations from specific surface modifications through to local manipulation of living cells, and provides a simplified and faster handling for already known experiments with fluid force microscopy. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 209 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-86592 ER - TY - GEN A1 - Megow, Jörg A1 - Röhr, Merle I. S. A1 - Schmidt am Busch, Marcel A1 - Renger, Thomas A1 - Mitrić, Roland A1 - Kirstein, Stefan A1 - Rabe, Jürgen P. A1 - May, Volkhard T1 - Site-dependence of van der Waals interaction explains exciton spectra of double-walled tubular J-aggregates N2 - The simulation of the optical properties of supramolecular aggregates requires the development of methods, which are able to treat a large number of coupled chromophores interacting with the environment. Since it is currently not possible to treat large systems by quantum chemistry, the Frenkel exciton model is a valuable alternative. In this work we show how the Frenkel exciton model can be extended in order to explain the excitonic spectra of a specific double-walled tubular dye aggregate explicitly taking into account dispersive energy shifts of ground and excited states due to van der Waals interaction with all surrounding molecules. The experimentally observed splitting is well explained by the site-dependent energy shift of molecules placed at the inner or outer side of the double-walled tube, respectively. Therefore we can conclude that inclusion of the site-dependent dispersive effect in the theoretical description of optical properties of nanoscaled dye aggregates is mandatory. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 191 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-79978 SP - 6741 EP - 6747 ER - TY - GEN A1 - Hildebrand, Viet A1 - Laschewsky, André A1 - Wischerhoff, Erik T1 - Modulating the solubility of zwitterionic poly((3- methacrylamidopropyl)ammonioalkane sulfonate)s in water and aqueous salt solutions via the spacer group separating the cationic and the anionic moieties N2 - Complementary to the well-established zwitterionic monomer 3-((3-methacrylamidopropyl)dimethylammonio) propane-1-sulfonate (SPP), the closely related monomers 2-hydroxy-3-((3-methacrylamidopropyl) dimethylammonio)propane-1-sulfonate (SHPP) and 4-((3-methacrylamidopropyl)dimethylammonio)-butane-1-sulfonate (SBP) were synthesised and polymerised by reversible addition–fragmentation chain transfer (RAFT) polymerisation, using a fluorophore labeled RAFT agent. The polyzwitterions of systematically varied molar masses were characterised with respect to their solubility in water and aqueous salt solutions. Both poly(sulfobetaine)s show thermoresponsive behaviour in water, exhibiting phase separation at low temperatures and upper critical solution temperatures (UCST). For both polySHPP and polySBP, cloud points depend notably on the molar mass, and are much higher in D2O than in H2O. Also, the cloud points are effectively modulated by the addition of salts. The individual effects can be in parts correlated to the Hofmeister series for the anions studied. Still, they depend in a complex way on the concentration and the nature of the added electrolytes, on the one hand, and on the detailed nature of the spacer group separating the anionic and the cationic charges of the betaine moiety, on the other hand. As anticipated, the cloud points of polySBP are much higher than the ones of the analogous polySPP of identical molar mass. Surprisingly, the cloud points of polySHPP are also somewhat higher than the ones of their polySPP analogues, despite the additional hydrophilic hydroxyl group present in the spacer separating the ammonium and the sulfonate moieties. These findings point to a complicated interplay of the various hydrophilic components in polyzwitterions with respect to their overall hydrophilicity. Thus, the spacer group in the betaine moiety proves to be an effective additional molecular design parameter, apparently small variations of which strongly influence the phase behaviour of the polyzwitterions in specific aqueous environments. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 309 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-103040 SP - 731 EP - 740 ER - TY - GEN A1 - Pape, Simon A1 - Wessig, Pablo A1 - Brunner, Heiko T1 - A new and environmentally benign synthesis of aroylguanidines using iron trichloride N2 - A new synthetic approach for the guanylation of aroylthioureas using iron trichloride is presented. Our synthetic method distinguishes itself by benign reaction conditions, low costs and a broad product spectrum. The scope of the reaction and calorimetric studies are described. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 308 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-102720 SP - 101408 EP - 101411 ER - TY - GEN A1 - Kumke, Michael Uwe A1 - Klier, Dennis Tobias T1 - Upconversion NaYF4:Yb:Er nanoparticles co-doped with Gd3+ and Nd3+ for thermometry on the nanoscale N2 - In the present work, the upconversion luminescence properties of oleic acid capped NaYF4:Gd3+:Yb3+:Er3+ upconversion nanoparticles (UCNP) with pure β crystal phase and Nd3+ ions as an additional sensitizer were studied in the temperature range of 288 K < T < 328 K. The results of this study showed that the complex interplay of different mechanisms and effects, causing the special temperature behavior of the UCNP can be developed into thermometry on the nanoscale, e.g. to be applied in biological systems on a cellular level. The performance was improved by the use of Nd3+ as an additional dopant utilizing the cascade sensitization mechanism in tri-doped UCNP. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 304 Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-102677 SP - 67149 EP - 67156 ER - TY - THES A1 - Feldbusch, Elvira T1 - Geochemische Charakterisierung eines Formationsfluids im Unteren Perm T1 - Geochemical characterization of a formation fluid of Lower Permian reservoir BT - Herkunft, betriebsbedingte Prozesse und Rolle organischer Verbindungen im geothermischen Kreislauf BT - origin, operational processes and role of organic compounds in the geothermal cycle N2 - Diese Arbeit befasst sich mit der ganzheitlichen Betrachtung der Fluideigenschaften eines unterpermischen Reservoirs am Geothermie Forschungsstandort Groß Schönebeck (GrSk) bei Reservoirbedingungen und im Betrieb der Geothermieanlage. Die Untersuchungen zur Fluidherkunft ergeben, dass es sich um ein konnates Wasser meteorischen Ursprungs ohne den Einfluss der darüberliegenden Zechsteinwässer handelt. Die Ionen und Isotopenverhältnisse im Formationswasser gelöster Komponenten in GrSk belegen einen gemeinsamen Genesepfad mit Wässern anderer Rotliegend-Reservoire des Nordostdeutschen Beckens (NEGB). Die Isotopenverhältnisse von ⁸⁷Sr/⁸⁶Sr ≈ 0,7158 und von δ³⁴SV CDT ≈ 4,1 ‰ des Sulfats weisen auf die Anreicherung des Fluids mit schweren Isotopen durch die Fluid Gestein-Wechselwirkung mit Vulkaniten und Rotliegend Sandsteinen des Unteren Perms hin. Das im Formationswasser bei Reservoirbedingungen gelöste Gas (Gas/Wasser ≤ 2 bei STP) enthält Stickstoff (δ¹⁵NAir ≈ 0,6 ‰) und thermogenes Methan (δ¹³CV-PDB ≈ - 18 ‰) aus organischen Karbonablagerungen (Kerogen Typ - III Kohlen) hoher Reife. Die Isotopenverhältnisse der Edelgase belegen eine krustale Herkunft des Gasgemisches. Die berechnete Verweilzeit τ (⁴He) der Gase im Reservoir liegt zwischen 275 und 317 Ma und überschreitet damit bei gegebener Konzentration von Mutternukliden im Reservoirgestein das allgemein angenommene Zeitalter der Sedimentgruppe. Das lässt sich durch eine Zuwanderung von Gasen aus älteren Sedimentfolgen erklären. Die Veränderungen der physikochemischen Fluidparameter während des Anlagenbetriebs sind hauptsächlich temperaturbedingt. Bei stabilen Produktionsbedingungen und einer Temperatur von ca. 100 °C stabilisieren sich auch die Fluideigenschaften. Bei In situ Bedingungen übertage beträgt die Dichte ρ = 1,1325 ± 0,0002 g ∙ mL⁻¹, das Redoxpotential Eh = -105,5 ± 1,3 mV und der pH = 6,61 ± 0,002. Die relative Zusammensetzung der Gasphase bei stabilen Produktionsbedingungen zeigt dagegen eine geringe Erhöhung des Stickstoffanteils sowie des Anteils der Kohlenwasserstoffe (Ethan, Propan, usw.) und Abnahme des relativen Methananteils im Laufe des Betriebs. Die quantitative Untersuchung der sekundären mineralischen Ausfällungen im Fluid mittels sequentieller Extraktion zeigte, dass Schwermetalle als eine Hauptkomponente der Fluidfestphase größtenteils in Verbindung mit organischen Molekülen vorliegen. Experimente zum Einfluss organischer Verbindungen unterschiedlicher Substanzklassen auf eine Mobilisierung der Schwermetalle aus dem Reservoirgestein ergaben, dass die Verbindungen wie Fettsäuren und PAK (polyzyklische aromatische Kohlenwasserstoffe) die Freisetzung von Kupfer, Nickel, Chrom und Blei verhindern bzw. zu derer Immobilisierung beitragen. Im Gegensatz dazu wird die Mobilität von Zink in Anwesenheit von diesen Verbindungen erhöht. Niedermolekulare Monocarbonsäuren und stickstoffhaltige Heteroaromaten tragen, mit Ausnahme von Blei, zur Freisetzung bzw. Mobilisierung von Schwermetallen aus dem Reservoirgestein bei. Die gewonnenen Erkenntnisse dieser Arbeit bestätigen das Risiko massiver Ausfällungen auf der kalten Seite der Geothermieanlage bei Inbetriebnahme des Kraftwerks, wenn keine an den Fluidchemismus angepassten Präventionsmethoden eingesetzt werden. Die Isotopenzusammensetzung der Fluidkomponenten sowie geringfügige Schwankungen der Gaszusammensetzung im kontinuierlichen Anlagenbetrieb lässt eine Kommunikation des unterpermischen Reservoirs mit dem darunter liegenden Oberkarbon vermuten, was eine nachträgliche Veränderung der Fluidzusammensetzung beim Dauerbetrieb der Anlage bedeuten kann. N2 - This work represents a holistic study of the properties of fluid from the Lower Permian reservoirs of the geothermal research site Gross Schönebeck at reservoir and at wellhead conditions during fluid circulation. Investigations of the fluid origin show that the formation water represents a connate water of meteoric origin without any evidence of influences from overlying Zechstein. The tracers of formation water as well as the isotopic signatures of relevant components reveal a common genesis path with waters of other Rotliegend reservoirs of the Northeast German Basin (NEGB). The isotope ratios of ⁸⁷Sr/⁸⁶Sr ≈ 0,7158 and sulphate δ³⁴SV-CDT ≈ 4,1 ‰ indicate strong water rock interaction with Lower Permian Rotliegend sandstones and volcanic rocks, resulting in an enrichment with 87Sr and 34S. The fluid dissolves about gas/water ≤ 2 (at STP) of formation gas at reservoir conditions. Major components are nitrogen (δ¹⁵NAir ≈ 0,6 ‰) and methane (δ¹³CV PDB ≈ - 18 ‰) of thermogenic origin from carboniferous organic matter with kerogen Type III coals of high maturity. The noble gases represent a gas mixture of crustal origin with a residence time τ (⁴He) in the reservoir of 275 - 317 Ma. This value exceeds commonly accepted age and parent radionuclide content of the stratigraphic group. This indicates migration of gases from older sediment layers. The changes of physico-chemical fluid properties above ground during plant operation are primarily temperature-affected. At steady operating conditions with a stable temperature of ~ 100 °C fluid properties stabilise with an in-situ density ρ = 1,1325 ± 0,0002 g ∙ mL⁻¹, redox potential Eh = -105,5 ± 1,3 mV and pH = 6,61 ± 0,002. The composition of formation gas at steady operating conditions shows a slight increase of nitrogen content and lower concentrated hydrocarbons (ethane, propane, etc.). Methane content decreases during fluid production, which could be an indicator for gas migration from different reservoir sections. A quantitative examination of secondary mineral precipitations in the fluid by means of sequential extractions indicates that heavy metals are largely bonded on the organic matter. Experiments on the impact different classes of organic components on the mobilisation of heavy metals from the reservoir rock demonstrated that the most heavy metals (Cu, Pb, Cr and Ni) can hardly be mobilized by fatty acids and polycyclic aromatic hydrocarbons or can be precipitated from the fluid. Zinc showed the opposite behaviour with these organic compounds. Organic components such as monocarboxylic acids and nitrogen heterocycles contribute to removing of heavy metals from the reservoir rock, with exception of lead. The findings of this work confirm the risk of considerable precipitation on the cold side of the geothermal plant during commissioning of the power station unless prevention methods adapted for the fluid chemistry are applied. The isotopic composition of fluid components as well as a minor fluctuation of gas composition during continuous plant operation indicates a potential communication of the Lower Permian reservoir with the underlying Upper Carboniferous formation. This may lead to a subsequent change of the fluid composition during a long-term operation of the plant in GrSk. KW - Groß Schönebeck KW - Rotliegend KW - Formationsfluid KW - Schwermetalle KW - Herkunft KW - geothermal KW - origin KW - formation fluid KW - heavy metals KW - onsite monitoring Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-87402 ER -