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529 results on '"Hinderberger, Dariush"'

7. Initiator‐Free Synthesis of Semi‐Interpenetrating Polymer Networks via Bergman Cyclization.

Author

Cai, Yue, Lehmann, Florian, Thümmler, Justus F., Hinderberger, Dariush, and Binder, Wolfgang H.

Subjects
ELECTRON paramagnetic resonance, POLYMERIZATION, POLYURETHANES, THERMAL stability, MEDICAL equipment, POLYMER networks, ELECTRON paramagnetic resonance spectroscopy
Abstract

Semi‐interpenetrating polymer networks (semi‐IPNs), composed of two or more polymers, forming intertwined network‐architectures, represent a significant type of polymer combination in modern industry, especially in automotive and medical devices. Diverse synthesis techniques and plentiful raw materials highlight semi‐IPNs in providing facile modifications of properties to meet specific needs. An initiator‐free synthesis of semi‐interpenetrating polymer networks via Bergman cyclization (BC) is reported here, acting as a trigger to embed a second polymer via its reactive enediyne (EDY) moiety, then embedded into the first network. (Z)‐oct‐4‐ene‐2,6‐diyne‐1,8‐diol (diol‐EDY) is targeted as the precursor of the second polymer, swollen into the first polyurethane network (PU), followed by a radical polymerization induced by the radicals formed by the BC. The formation of the semi‐IPN is monitored via electron paramagnetic resonance (EPR) spectroscopy, infrared‐spectroscopy (FT‐IR), and thermal methods (DSC), proving the activation of the EDY‐moiety and its subsequent polymerization to form the second polymer. Stress−strain characterization and cyclic stress−strain investigations, together with TGA and DTG analysis, illustrate improved mechanical properties and thermal stability of the formed semi‐IPN compared to the initial PU‐network. The method presented here is a novel and broadly applicable approach to generate semi‐IPNs, triggered by the EDY‐activation via Bergman cyclization. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Characterization of the active site in the thiocyanate-forming protein from Thlaspi arvense (TaTFP) using EPR spectroscopy.

Author

Hashemi Haeri, Haleh, Schneegans, Nicola, Eisenschmidt-Bönn, Daniela, Brandt, Wolfgang, Wittstock, Ute, and Hinderberger, Dariush

Subjects
ELECTRON paramagnetic resonance spectroscopy, ELECTRON paramagnetic resonance, IRON proteins, ELECTRON configuration, IRON, OCHRATOXINS
Abstract

Glucosinolates are plant thioglucosides, which act as chemical defenses. Upon tissue damage, their myrosinase-catalyzed hydrolysis yields aglucones that rearrange to toxic isothiocyanates. Specifier proteins such as thiocyanate-forming protein from Thlaspi arvense (TaTFP) are non-heme iron proteins, which capture the aglucone to form alternative products, e.g. nitriles or thiocyanates. To resolve the electronic state of the bound iron cofactor in TaTFP, we applied continuous wave electron paramagnetic resonance (CW EPR) spectroscopy at X-and Q-band frequencies (∼9.4 and ∼34 GHz). We found characteristic features of high spin and low spin states of a d5 electronic configuration and local rhombic symmetry during catalysis. We monitored the oxidation states of bound iron during conversion of allylglucosinolate by myrosinase and TaTFP in presence and absence of supplemented Fe2+. Without added Fe2+, most high spin features of bound Fe3+ were preserved, while different g'-values of the low spin part indicated slight rearrangements in the coordination sphere and/or structural geometry. We also examined involvement of the redox pair Fe3+/Fe2 in samples with supplemented Fe2+. The absence of any EPR signal related to Fe3+ or Fe2+ using an iron-binding deficient TaTFP variant allowed us to conclude that recorded EPR signals originated from the bound iron cofactor. [ABSTRACT FROM AUTHOR]

Published
2024
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23. Tuning the internal compartmentation of single-chain nanoparticles as fluorescent contrast agents

Author

Thümmler, Justus F., Kampe, Andreas Helmut, Krüger, Jana, Hinderberger, Dariush, Schmitt, Franz-Josef, Tang, Guo, Golmohamadi, Farzin Ghane, Laufer, Jan, and Binder, Wolfgang H.

Abstract

Controlling the internal structures of single-chain nanoparticles (SCNPs) is an important factor for their targeted chemical design and synthesis, especially in view of nanosized compartments presenting different local environments as a main feature to control functionality. We here design SCNPs bearing near-infrared fluorescent dyes embedded in hydrophobic compartments for use as contrast agents in pump–probe photoacoustic (PA) imaging, displaying improved properties by the location of the dye in the hydrophobic particle core. Compartment formation is controlled via single-chain collapse and subsequent crosslinking of an amphiphilic polymer using external crosslinkers in reaction media of adjustable polarity. Different SCNPs with hydrodynamic diameters of 6-12 nm bearing adjustable label densities are synthesized. It is found that the specific conditions for single-chain collapse have a major impact on the formation of the desired core–shell structure, in turn adjusting the internal nanocompartments together with the formation of excitonic dye couples, which in turn increase their fluorescence lifetime and PA signal generation. SCNPs with the dye molecules accumulate at the core also show a nonlinear PA response as a function of pulse energy—a property that can be exploited as a contrast mechanism in molecular PA tomography.

Published
2023
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29. Glycation Alters the Fatty Acid Binding Capacity of Human Serum Albumin

Author

Henning, Christian, primary, Stübner, Christine, additional, Arabi, Seyed Hamidreza, additional, Reichenwallner, Jörg, additional, Hinderberger, Dariush, additional, Fiedler, Roman, additional, Girndt, Matthias, additional, Di Sanzo, Simone, additional, Ori, Alessandro, additional, and Glomb, Marcus A., additional

Published
2022
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33. Incorporation of β‐Alanine in Cu(II) ATCUN Peptide Complexes Increases ROS Levels, DNA Cleavage and Antiproliferative Activity**

Author

Heinrich, Julian, primary, Bossak‐Ahmad, Karolina, additional, Riisom, Mie, additional, Haeri, Haleh H., additional, Steel, Tasha R., additional, Hergl, Vinja, additional, Langhans, Alexander, additional, Schattschneider, Corinna, additional, Barrera, Jannis, additional, Jamieson, Stephen M. F., additional, Stein, Matthias, additional, Hinderberger, Dariush, additional, Hartinger, Christian G., additional, Bal, Wojciech, additional, and Kulak, Nora, additional

Published
2021
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37. Nanoscale Model System for the Human Myelin Sheath

Author

Hoffmann, Matthias, primary, Haselberger, David, additional, Hofmann, Tommy, additional, Müller, Lisa, additional, Janson, Kevin, additional, Meister, Annette, additional, Das, Manabendra, additional, Vargas, Carolyn, additional, Keller, Sandro, additional, Kastritis, Panagiotis L., additional, Schmidt, Carla, additional, and Hinderberger, Dariush, additional

Published
2021
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39. A Nanoscale Model System for the Human Myelin Sheath

Author

Hoffmann, Matthias, primary, Haselberger, David, primary, Hofmann, Tommy, primary, Müller, Lisa, primary, Janson, Kevin, primary, Meister, Annette, primary, das, manabendra, primary, Vargas, Carolyn, primary, Keller, Sandro, primary, Kastritis, Panagiotis L., primary, Schmidt, Carla, primary, and Hinderberger, Dariush, primary

Published
2021
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47. Probing the Y2 Receptor on Transmembrane, Intra- and Extra-Cellular Sites for EPR Measurements

Author

Laugwitz, Jeannette M., Haeri, Haleh H., Kaiser, Anette, Krug, Ulrike, Hinderberger, Dariush, Beck-Sickinger, Annette G., Schmidt, Peter, Laugwitz, Jeannette M., Haeri, Haleh H., Kaiser, Anette, Krug, Ulrike, Hinderberger, Dariush, Beck-Sickinger, Annette G., and Schmidt, Peter

Abstract

The function of G protein-coupled receptors is intrinsically linked to their conformational dynamics. In conjugation with site-directed spin labeling, electron paramagnetic resonance (EPR) spectroscopy provides powerful tools to study the highly dynamic conformational states of these proteins. Here, we explored positions for nitroxide spin labeling coupled to single cysteines, introduced at transmembrane, intra- and extra-cellular sites of the human neuropeptide Y2 receptor. Receptor mutants were functionally analyzed in cell culture system, expressed in Escherichia coli fermentation with yields of up to 10 mg of purified protein per liter expression medium and functionally reconstituted into a lipid bicelle environment. Successful spin labeling was confirmed by a fluorescence assay and continuous wave EPR measurements. EPR spectra revealed mobile and immobile populations, indicating multiple dynamic conformational states of the receptor. We found that the singly mutated positions by MTSL ((1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl) methyl methanesulfonothioate) have a water exposed immobilized conformation as their main conformation, while in case of the IDSL (bis(1-oxyl-2,2,5,5-tetramethyl-3-imidazolin-4-yl) disulfide) labeled positions, the main conformation are mainly of hydrophobic nature. Further, double cysteine mutants were generated and examined for potential applications of distance measurements by double electron–electron resonance (DEER) pulsed EPR technique on the receptor.

Published
2020

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