TY - JOUR
A1 - Schulze-Makuch, Dirk
A1 - Wagner, Dirk
A1 - Kounaves, Samuel P.
A1 - Mangelsdorf, Kai
A1 - Devine, Kevin G.
A1 - de Vera, Jean-Pierre
A1 - Schmitt-Kopplin, Philippe
A1 - Grossart, Hans-Peter
A1 - Parro, Victor
A1 - Kaupenjohann, Martin
A1 - Galy, Albert
A1 - Schneider, Beate
A1 - Airo, Alessandro
A1 - Froesler, Jan
A1 - Davila, Alfonso F.
A1 - Arens, Felix L.
A1 - Caceres, Luis
A1 - Cornejo, Francisco Solis
A1 - Carrizo, Daniel
A1 - Dartnell, Lewis
A1 - DiRuggiero, Jocelyne
A1 - Flury, Markus
A1 - Ganzert, Lars
A1 - Gessner, Mark O.
A1 - Grathwohl, Peter
A1 - Guan, Lisa
A1 - Heinz, Jacob
A1 - Hess, Matthias
A1 - Keppler, Frank
A1 - Maus, Deborah
A1 - McKay, Christopher P.
A1 - Meckenstock, Rainer U.
A1 - Montgomery, Wren
A1 - Oberlin, Elizabeth A.
A1 - Probst, Alexander J.
A1 - Saenz, Johan S.
A1 - Sattler, Tobias
A1 - Schirmack, Janosch
A1 - Sephton, Mark A.
A1 - Schloter, Michael
A1 - Uhl, Jenny
A1 - Valenzuela, Bernardita
A1 - Vestergaard, Gisle
A1 - Woermer, Lars
A1 - Zamorano, Pedro
T1 - Transitory microbial habitat in the hyperarid Atacama Desert
JF - Proceedings of the National Academy of Sciences of the United States of America
KW - habitat
KW - aridity
KW - microbial activity
KW - biomarker
KW - Mars
Y1 - 2018
U6 - https://doi.org/10.1073/pnas.1714341115
SN - 0027-8424
VL - 115
IS - 11
SP - 2670
EP - 2675
PB - National Acad. of Sciences
CY - Washington
ER -
TY - JOUR
A1 - Kuntze, Kim
A1 - Viljakka, Jani
A1 - Titov, Evgenii
A1 - Ahmed, Zafar
A1 - Kalenius, Elina
A1 - Saalfrank, Peter
A1 - Priimagi, Arri
T1 - Towards low-energy-light-driven bistable photoswitches
BT - ortho-fluoroaminoazobenzenes
JF - Photochemical & photobiological sciences / European Society for Photobiology
N2 - Thermally stable photoswitches that are driven with low-energy light are rare, yet crucial for extending the applicability of photoresponsive molecules and materials towards, e.g., living systems. Combined ortho-fluorination and -amination couples high visible light absorptivity of o-aminoazobenzenes with the extraordinary bistability of o-fluoroazobenzenes. Herein, we report a library of easily accessible o-aminofluoroazobenzenes and establish structure-property relationships regarding spectral qualities, visible light isomerization efficiency and thermal stability of the cis-isomer with respect to the degree of o-substitution and choice of amino substituent. We rationalize the experimental results with quantum chemical calculations, revealing the nature of low-lying excited states and providing insight into thermal isomerization. The synthesized azobenzenes absorb at up to 600 nm and their thermal cis-lifetimes range from milliseconds to months. The most unique example can be driven from trans to cis with any wavelength from UV up to 595 nm, while still exhibiting a thermal cis-lifetime of 81 days.
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Y1 - 2022
U6 - https://doi.org/10.1007/s43630-021-00145-4
SN - 1474-905X
SN - 1474-9092
VL - 21
IS - 2
SP - 159
EP - 173
PB - Springer
CY - Heidelberg
ER -
TY - JOUR
A1 - Neffe, Axel T.
A1 - Löwenberg, Candy
A1 - Julich-Gruner, Konstanze K.
A1 - Behl, Marc
A1 - Lendlein, Andreas
T1 - Thermally-induced shape-memory behavior of degradable gelatin-based networks
JF - International journal of molecular sciences
N2 - Shape-memory hydrogels (SMH) are multifunctional, actively-moving polymers of interest in biomedicine. In loosely crosslinked polymer networks, gelatin chains may form triple helices, which can act as temporary net points in SMH, depending on the presence of salts. Here, we show programming and initiation of the shape-memory effect of such networks based on a thermomechanical process compatible with the physiological environment. The SMH were synthesized by reaction of glycidylmethacrylated gelatin with oligo(ethylene glycol) (OEG) alpha,omega-dithiols of varying crosslinker length and amount. Triple helicalization of gelatin chains is shown directly by wide-angle X-ray scattering and indirectly via the mechanical behavior at different temperatures. The ability to form triple helices increased with the molar mass of the crosslinker. Hydrogels had storage moduli of 0.27-23 kPa and Young's moduli of 215-360 kPa at 4 degrees C. The hydrogels were hydrolytically degradable, with full degradation to water-soluble products within one week at 37 degrees C and pH = 7.4. A thermally-induced shape-memory effect is demonstrated in bending as well as in compression tests, in which shape recovery with excellent shape-recovery rates R-r close to 100% were observed. In the future, the material presented here could be applied, e.g., as self-anchoring devices mechanically resembling the extracellular matrix.
KW - shape-memory hydrogel
KW - active polymer
KW - biopolymer
KW - mechanical
KW - properties
KW - degradation
Y1 - 2021
U6 - https://doi.org/10.3390/ijms22115892
SN - 1422-0067
SN - 1661-6596
VL - 22
IS - 11
PB - Molecular Diversity Preservation International
CY - Basel
ER -
TY - JOUR
A1 - Koetz, Joachim
T1 - The Effect of Surface Modification of Gold Nanotriangles for Surface-Enhanced Raman Scattering Performance
JF - Nanomaterials
N2 - A surface modification of ultraflat gold nanotriangles (AuNTs) with different shaped nanoparticles is of special relevance for surface-enhanced Raman scattering (SERS) and the photo-catalytic activity of plasmonic substrates. Therefore, different approaches are used to verify the flat platelet morphology of the AuNTs by oriented overgrowth with metal nanoparticles. The most important part for the morphological transformation of the AuNTs is the coating layer, containing surfactants or polymers. By using well established AuNTs stabilized by a dioctyl sodium sulfosuccinate (AOT) bilayer, different strategies of surface modification with noble metal nanoparticles are possible. On the one hand undulated superstructures were synthesized by in situ growth of hemispherical gold nanoparticles in the polyethyleneimine (PEI)-coated AOT bilayer of the AuNTs. On the other hand spiked AuNTs were obtained by a direct reduction of Au³⁺ ions in the AOT double layer in presence of silver ions and ascorbic acid as reducing agent. Additionally, crumble topping of the smooth AuNTs can be realized after an exchange of the AOT bilayer by hyaluronic acid, followed by a silver-ion mediated reduction with ascorbic acid. Furthermore, a decoration with silver nanoparticles after coating the AOT bilayer with the cationic surfactant benzylhexadecyldimethylammonium chloride (BDAC) can be realized. In that case the ultraviolet (UV)-absorption of the undulated Au@Ag nanoplatelets can be tuned depending on the degree of decoration with silver nanoparticles. Comparing the Raman scattering data for the plasmon driven dimerization of 4-nitrothiophenol (4-NTP) to 4,4′-dimercaptoazobenzene (DMAB) one can conclude that the most important effect of surface modification with a 75 times higher enhancement factor in SERS experiments becomes available by decoration with gold spikes.
KW - undulated
KW - spiked and crumble gold nanotriangles
KW - SERS enhancement factor
KW - dimerization of 4-nitrothiophenol
KW - AOT bilayer
KW - PEI coating
Y1 - 2020
U6 - https://doi.org/10.3390/nano10112187
SN - 2079-4991
VL - 10
IS - 11
PB - MDPI
CY - Basel
ER -
TY - GEN
A1 - Koetz, Joachim
T1 - The Effect of Surface Modification of Gold Nanotriangles for Surface-Enhanced Raman Scattering Performance
T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2 - A surface modification of ultraflat gold nanotriangles (AuNTs) with different shaped nanoparticles is of special relevance for surface-enhanced Raman scattering (SERS) and the photo-catalytic activity of plasmonic substrates. Therefore, different approaches are used to verify the flat platelet morphology of the AuNTs by oriented overgrowth with metal nanoparticles. The most important part for the morphological transformation of the AuNTs is the coating layer, containing surfactants or polymers. By using well established AuNTs stabilized by a dioctyl sodium sulfosuccinate (AOT) bilayer, different strategies of surface modification with noble metal nanoparticles are possible. On the one hand undulated superstructures were synthesized by in situ growth of hemispherical gold nanoparticles in the polyethyleneimine (PEI)-coated AOT bilayer of the AuNTs. On the other hand spiked AuNTs were obtained by a direct reduction of Au³⁺ ions in the AOT double layer in presence of silver ions and ascorbic acid as reducing agent. Additionally, crumble topping of the smooth AuNTs can be realized after an exchange of the AOT bilayer by hyaluronic acid, followed by a silver-ion mediated reduction with ascorbic acid. Furthermore, a decoration with silver nanoparticles after coating the AOT bilayer with the cationic surfactant benzylhexadecyldimethylammonium chloride (BDAC) can be realized. In that case the ultraviolet (UV)-absorption of the undulated Au@Ag nanoplatelets can be tuned depending on the degree of decoration with silver nanoparticles. Comparing the Raman scattering data for the plasmon driven dimerization of 4-nitrothiophenol (4-NTP) to 4,4′-dimercaptoazobenzene (DMAB) one can conclude that the most important effect of surface modification with a 75 times higher enhancement factor in SERS experiments becomes available by decoration with gold spikes.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1022
KW - undulated
KW - spiked and crumble gold nanotriangles
KW - SERS enhancement factor
KW - dimerization of 4-nitrothiophenol
KW - AOT bilayer
KW - PEI coating
Y1 - 2020
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-485172
SN - 1866-8372
IS - 1022
ER -
TY - GEN
A1 - Lohren, Hanna
A1 - Bornhorst, Julia
A1 - Galla, Hans-Joachim
A1 - Schwerdtle, Tanja
T1 - The blood–cerebrospinal fluid barrier
BT - First evidence for an active transport of organic mercury compounds out of the brain
N2 - Exposure to organic mercury compounds promotes primarily neurological effects. Although methylmercury is recognized as a potent neurotoxicant, its transfer into the central nervous system (CNS) is not fully evaluated. While methylmercury and thiomersal pass the blood–brain barrier, limited data are available regarding the second brain regulating interface, the blood–cerebrospinal fluid (CSF) barrier. This novel study was designed to investigate the effects of organic as well as inorganic mercury compounds on, and their transfer across, a porcine in vitro model of the blood–CSF barrier for the first time. The barrier system is significantly more sensitive towards organic Hg compounds as compared to inorganic compounds regarding the endpoints cytotoxicity and barrier integrity. Whereas there are low transfer rates from the blood side to the CSF side, our results strongly indicate an active transfer of the organic mercury compounds out of the CSF. These results are the first to demonstrate an efflux of organic mercury compounds regarding the CNS and provide a completely new approach in the understanding of mercury compounds specific transport.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 200
Y1 - 2015
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-82089
ER -
TY - JOUR
A1 - Zabel, André
A1 - Winter, Alette
A1 - Kelling, Alexandra
A1 - Schilde, Uwe
A1 - Strauch, Peter
T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR
JF - International journal of molecular sciences
N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids.
KW - tetrabromidocuprate(II)
KW - X-ray structure
KW - electron paramagnetic resonance
KW - copper(II)
Y1 - 2016
U6 - https://doi.org/10.3390/ijms17040596
VL - 17
IS - 4
PB - MDPI
CY - Basel
ER -
TY - GEN
A1 - Zabel, André
A1 - Winter, Alette
A1 - Kelling, Alexandra
A1 - Schilde, Uwe
A1 - Strauch, Peter
T1 - Tetrabromidocuprates(II)-Synthesis, Structure and EPR
N2 - Metal-containing ionic liquids (ILs) are of interest for a variety of technical applications, e.g., particle synthesis and materials with magnetic or thermochromic properties. In this paper we report the synthesis of, and two structures for, some new tetrabromidocuprates(II) with several “onium” cations in comparison to the results of electron paramagnetic resonance (EPR) spectroscopic analyses. The sterically demanding cations were used to separate the paramagnetic Cu(II) ions for EPR measurements. The EPR hyperfine structure in the spectra of these new compounds is not resolved, due to the line broadening resulting from magnetic exchange between the still-incomplete separated paramagnetic Cu(II) centres. For the majority of compounds, the principal g values (g|| and gK) of the tensors could be determined and information on the structural changes in the [CuBr4]2- anions can be obtained. The complexes have high potential, e.g., as ionic liquids, as precursors for the synthesis of copper bromide particles, as catalytically active or paramagnetic ionic liquids.
T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 226
KW - tetrabromidocuprate(II)
KW - X-ray structure
KW - electron paramagnetic resonance
KW - copper(II)
Y1 - 2016
U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-91470
ER -
TY - THES
A1 - Nacak, Selma
T1 - Synthesis and Characterization of Upconversion Nanaparticles for Applications in Life Sciences
Y1 - 2021
ER -
TY - JOUR
A1 - Schönemann, Eric
A1 - Koc, Julian
A1 - Karthäuser, Jana
A1 - Özcan, Onur
A1 - Schanzenbach, Dirk
A1 - Schardt, Lisa
A1 - Rosenhahn, Axel
A1 - Laschewsky, André
T1 - Sulfobetaine methacrylate polymers of unconventional polyzwitterion architecture and their antifouling properties
JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences
N2 - Combining high hydrophilicity with charge neutrality, polyzwitterions are intensely explored for their high biocompatibility and low-fouling properties. Recent reports indicated that in addition to charge neutrality, the zwitterion's segmental dipole orientation is an important factor for interacting with the environment. Accordingly, a series of polysulfobetaines with a novel architecture was designed, in which the cationic and anionic groups of the zwitterionic moiety are placed at equal distances from the backbone. They were investigated by in vitro biofouling assays, covering proteins of different charges and model marine organisms. All polyzwitterion coatings reduced the fouling effectively compared to model polymer surfaces of poly(butyl methacrylate), with a nearly equally good performance as the reference polybetaine poly(3-(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylammonio)propanesulfonate). The specific fouling resistance depended on the detailed chemical structure of the polyzwitterions. Still, while clearly affecting the performance, the precise dipole orientation of the sulfobetaine group in the polyzwitterions seems overall to be only of secondary importance for their antifouling behavior.
Y1 - 2021
U6 - https://doi.org/10.1021/acs.biomac.0c01705
SN - 1525-7797
SN - 1526-4602
VL - 22
IS - 4
SP - 1494
EP - 1508
PB - American Chemical Society
CY - Washington
ER -