TY  - GEN
A1  - Kort, C. A. D. de
A1  - Peter, Martin G.
A1  - Koopmanschap, A. B.
T1  - Binding and degradation of juvenile hormone III by haemolymph proteins of the Colorado potato beetle: a re-examination
N2  - The haemolymph of the adult Colorado potato beetle, Lepinotarsa decemlineata Say, contains a high molecular weight (MW > 200,000) JH-III specific binding protein. The Kd value of the protein for racemic JH-III is 1.3 ± 0.2 × 10−7 M. It has a lower affinity for racemic JH-I and it does not bind JH-III-diol or JH-III-acid. The binding protein does discriminate between the enantiomers of synthetic, racemic JH-III as was determined by stereochemical anaysis of the bound and the free JH-III. Incubation of racemic JH-III with crude haemolymph results in preferential formation of (10S)-JH-III-acid, the unnatural configuration. The JH-esterase present in L. decemlineata haemolymph is not enantioselective. It is concluded that the most important function of the binding protein is that of a specific carrier, protecting the natural hormone against degradation by esterases. The carrier does not protect JH-I as efficiently as the lower homologue.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 068 
KW  - Juvenile hormone
KW  - Leptinotarsa decemlineata
KW  - JH-III-specific carrier protein
KW  - enantioselectivity
Y1  - 1983
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16777
ER  - 
TY  - JOUR
A1  - Reschke, Stefan
A1  - Mebs, Stefan
A1  - Sigfridsson-Clauss, Kajsa G. V.
A1  - Kositzki, Ramona
A1  - Leimkühler, Silke
A1  - Haumann, Michael
T1  - Protonation and Sulfido versus Oxo Ligation Changes at the Molybdenum Cofactor in Xanthine Dehydrogenase (XDH) Variants Studied by X-ray Absorption Spectroscopy
JF  - Inorganic chemistry
N2  - Enzymes of the xanthine oxidase family are among the best characterized mononuclear molybdenum enzymes. Open questions about their mechanism of transfer of an oxygen atom to the substrate remain. The enzymes share a molybdenum cofactor (Moco) with the metal ion binding a molybdopterin (MPT) molecule via its dithiolene function and terminal sulfur and oxygen groups. For xanthine dehydrogenase (XDH) from the bacterium Rhodobacter capsulatus, we used X-ray absorption spectroscopy to determine the Mo site structure, its changes in a pH range of 5-10, and the influence of amino acids (Glu730 and Gln179) close to Moco in wild-type (WT), Q179A, and E730A variants, complemented by enzyme kinetics and quantum chemical studies. Oxidized WT and Q179A revealed a similar Mo (VI) ion with each one MPT, Mo=O, Mo-O-, and Mo=S ligand, and a weak Mo-O(E730) bond at alkaline pH. Protonation of an oxo to a hydroxo (OH) ligand (pK similar to 6.8) causes inhibition of XDH at acidic pH, whereas deprotonated xanthine (pK similar to 8.8) is an inhibitor at alkaline pH. A similar acidic pK for the WT and Q179A. variants, as well as the metrical parameters of the Mo site and density functional theory calculations, suggested protonation at the equatorial oxo group. The sulfido was replaced with an oxo ligand in the inactive E730A variant, further showing another oxo and one Mo OH ligand at Mo, which are independent of pH. Our findings suggest a reaction mechanism for XDH in which an initial oxo rather than a hydroxo group and the sulfido ligand are essential for xanthine oxidation.
Y1  - 2017
U6  - https://doi.org/10.1021/acs.inorgchem.6b02846
SN  - 0020-1669
SN  - 1520-510X
VL  - 56
IS  - 4
SP  - 2165
EP  - 2176
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Braune, Steffen
A1  - Latour, Robert A.
A1  - Reinthaler, Markus
A1  - Landmesser, Ulf
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - In Vitro Thrombogenicity Testing of Biomaterials
JF  - Advanced healthcare materials
N2  - The short- and long-term thrombogenicity of implant materials is still unpredictable, which is a significant challenge for the treatment of cardiovascular diseases. A knowledge-based approach for implementing biofunctions in materials requires a detailed understanding of the medical device in the biological system. In particular, the interplay between material and blood components/cells as well as standardized and commonly acknowledged in vitro test methods allowing a reproducible categorization of the material thrombogenicity requires further attention. Here, the status of in vitro thrombogenicity testing methods for biomaterials is reviewed, particularly taking in view the preparation of test materials and references, the selection and characterization of donors and blood samples, the prerequisites for reproducible approaches and applied test systems. Recent joint approaches in finding common standards for a reproducible testing are summarized and perspectives for a more disease oriented in vitro thrombogenicity testing are discussed.
KW  - biomaterials
KW  - blood tests
KW  - implants
KW  - in vitro
KW  - thrombogenicity
Y1  - 2019
U6  - https://doi.org/10.1002/adhm.201900527
SN  - 2192-2640
SN  - 2192-2659
VL  - 8
IS  - 21
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Lu, Yong-Ping
A1  - Reichetzeder, Christoph
A1  - Prehn, Cornelia
A1  - von Websky, Karoline
A1  - Slowinski, Torsten
A1  - Chen, You-Peng
A1  - Yin, Liang-Hong
A1  - Kleuser, Burkhard
A1  - Yang, Xue-Song
A1  - Adamski, Jerzy
A1  - Hocher, Berthold
T1  - Fetal serum metabolites are independently associated with Gestational diabetes mellitus
JF  - Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology
N2  - Background/Aims: Gestational diabetes (GDM) might be associated with alterations in the metabolomic profile of affected mothers and their offspring. Until now, there is a paucity of studies that investigated both, the maternal and the fetal serum metabolome in the setting of GDM. Mounting evidence suggests that the fetus is not just passively affected by gestational disease but might play an active role in it. Metabolomic studies performed in maternal blood and fetal cord blood could help to better discern distinct fetal from maternal disease interactions. Methods: At the time of birth, serum samples from mothers and newborns (cord blood samples) were collected and screened for 163 metabolites utilizing tandem mass spectrometry. The cohort consisted of 412 mother/child pairs, including 31 cases of maternal GDM. Results: An initial non-adjusted analysis showed that eight metabolites in the maternal blood and 54 metabolites in the cord blood were associated with GDM. After Benjamini-Hochberg (BH) procedure and adjustment for confounding factors for GDM, fetal phosphatidylcholine acyl-alkyl C 32:1 and proline still showed an independent association with GDM. Conclusions: This study found metabolites in cord blood which were associated with GDM, even after adjustment for established risk factors of GDM. To the best of our knowledge, this is the first study demonstrating an independent association between fetal serum metabolites and maternal GDM. Our findings might suggest a potential effect of the fetal metabolome on maternal GDM. (c) 2018 The Author(s) Published by S. Karger AG, Basel
KW  - Gestational diabetes
KW  - Metabolomics
KW  - Phosphatidylcholine acyl-alkyl C 32:1
KW  - Proline
Y1  - 2018
U6  - https://doi.org/10.1159/000487119
SN  - 1015-8987
SN  - 1421-9778
VL  - 45
IS  - 2
SP  - 625
EP  - 638
PB  - Karger
CY  - Basel
ER  - 
TY  - JOUR
A1  - López de Guereñu Kurganova, Anna
A1  - Klier, Dennis Tobias
A1  - Haubitz, Toni
A1  - Kumke, Michael Uwe
T1  - Influence of Gd3+ doping concentration on the properties of Na(Y,Gd)F-4
BT  - Yb3+, Tm3+ upconverting nanoparticles and their long-term aging behavior
JF  - Photochemical & photobiological sciences / European Society for Photobiology
N2  - We present a systematic study on the properties of Na(Y,Gd)F-4-based upconverting nanoparticles (UCNP) doped with 18% Yb3+, 2% Tm3+, and the influence of Gd3+ (10-50 mol% Gd3+). UCNP were synthesized via the solvothermal method and had a range of diameters within 13 and 50 nm. Structural and photophysical changes were monitored for the UCNP samples after a 24-month incubation period in dry phase and further redispersion. Structural characterization was performed by means of X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as dynamic light scattering (DLS), and the upconversion luminescence (UCL) studies were executed at various temperatures (from 4 to 295 K) using time-resolved and steady-state spectroscopy. An increase in the hexagonal lattice phase with the increase of Gd3+ content was found, although the cubic phase was prevalent in most samples. The Tm3+-luminescence intensity as well as the Tm3+-luminescence decay times peaked at the Gd3+ concentration of 30 mol%. Although the general upconverting luminescence properties of the nanoparticles were preserved, the 24-month incubation period lead to irreversible agglomeration of the UCNP and changes in luminescence band ratios and lifetimes.
KW  - Upconversion luminescence
KW  - Lanthanides
KW  - Near infra-red
KW  - Ultra-low
KW  - temperature
KW  - Time-resolved spectroscopy
Y1  - 2022
U6  - https://doi.org/10.1007/s43630-021-00161-4
SN  - 1474-905X
SN  - 1474-9092
VL  - 21
IS  - 2
SP  - 235
EP  - 245
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - GEN
A1  - Peter, Martin G.
T1  - Products of in vitro oxidation of N-acetyldopamine as possible components in the sclerotization of insect cuticle
N2  - [1-14C]-N-Acetyldopamine (NADA) was oxidized in the presence of methyl [3-3H]-β-alanate with mushroom tyrosinase. The complex mixture of reaction products was partly resolved by chromatographic procedures and analyzed by spectroscopic methods. Methyl-β-alanate is incorporated to only a small extent into oxidation products of NADA which inter alia are presumed to be oligomeric hydroxyquinones. After oxidation of [1-14C, 2-3H]-NADA with preparations from tanning Manduca sexta pupal cuticle, N-acetylnoradrenalin was identified as one of the products. Binding of radioactivity to melanin-like material was also observed. These results suggest that oxidation products different from those formulated usually for the crosslinkages between protein amino groups and N-acetyldopaquinone are deposited in darkly brown coloured insect cuticles during sclerotization.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 041 
KW  - N-acetyldopamine
KW  - sclerotization
KW  - tyrosinase; o-quinones
KW  - tanning agents
Y1  - 1980
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-16759
ER  - 
TY  - JOUR
A1  - Liu, Yue
A1  - Gould, Oliver E. C.
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - On demand sequential release of (sub)micron particles controlled by size and temperature
JF  - Small : nano micro
N2  - Polymeric devices capable of releasing submicron particles (subMP) on demand are highly desirable for controlled release systems, sensors, and smart surfaces. Here, a temperature-memory polymer sheet with a programmable smooth surface served as matrix to embed and release polystyrene subMP controlled by particle size and temperature. subMPs embedding at 80 degrees C can be released sequentially according to their size (diameter D of 200 nm, 500 nm, 1 mu m) when heated. The differences in their embedding extent are determined by the various subMPs sizes and result in their distinct release temperatures. Microparticles of the same size (D approximate to 1 mu m) incorporated in films at different programming temperatures T-p (50, 65, and 80 degrees C) lead to a sequential release based on the temperature-memory effect. The change of apparent height over the film surface is quantified using atomic force microscopy and the realization of sequential release is proven by confocal laser scanning microscopy. The demonstration and quantification of on demand subMP release are of technological impact for assembly, particle sorting, and release technologies in microtechnology, catalysis, and controlled release.
KW  - on demand particle release
KW  - temperature-memory effect
KW  - thermosensitive
KW  - polymer surface
Y1  - 2022
U6  - https://doi.org/10.1002/smll.202104621
SN  - 1613-6810
SN  - 1613-6829
VL  - 18
IS  - 5
PB  - Wiley-VCH
CY  - Weinheim
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  - JOUR
A1  - Deng, Zijun
A1  - Zou, Jie
A1  - Wang, Weiwei
A1  - Nie, Yan
A1  - Tung, Wing-Tai
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Dedifferentiation of mature adipocytes with periodic exposure to cold
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - Lipid-containing adipocytes can dedifferentiate into fibroblast-like cells under appropriate culture conditions, which are known as dedifferentiated fat (DFAT) cells. However, the relative low dedifferentiation efficiency with the established protocols limit their widespread applications. In this study, we found that adipocyte dedifferentiation could be promoted via periodic exposure to cold (10 degrees C) in vitro. The lipid droplets in mature adipocytes were reduced by culturing the cells in periodic cooling/heating cycles (10-37 degrees C) for one week. The periodic temperature change led to the down-regulation of the adipogenic genes (FABP4, Leptin) and up-regulation of the mitochondrial uncoupling related genes (UCP1, PGC-1 alpha, and PRDM16). In addition, the enhanced expression of the cell proliferation marker Ki67 was observed in the dedifferentiated fibroblast-like cells after periodic exposure to cold, as compared to the cells cultured in 37 degrees C. Our in vitro model provides a simple and effective approach to promote lipolysis and can be used to improve the dedifferentiation efficiency of adipocytes towards multipotent DFAT cells.
KW  - Adipocyte
KW  - dedifferentiation
KW  - cold
KW  - lipid
Y1  - 2019
U6  - https://doi.org/10.3233/CH-199005
SN  - 1386-0291
SN  - 1875-8622
VL  - 71
IS  - 4
SP  - 415
EP  - 424
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Ebel, Kenny
A1  - Bald, Ilko
T1  - Length and Energy Dependence of Low-Energy Electron-Induced Strand Breaks in Poly(A) DNA
JF  - International Journal of Molecular Sciences
N2  - The DNA in living cells can be effectively damaged by high-energy radiation, which can lead to cell death. Through the ionization of water molecules, highly reactive secondary species such as low-energy electrons (LEEs) with the most probable energy around 10 eV are generated, which are able to induce DNA strand breaks via dissociative electron attachment. Absolute DNA strand break cross sections of specific DNA sequences can be efficiently determined using DNA origami nanostructures as platforms exposing the target sequences towards LEEs. In this paper, we systematically study the effect of the oligonucleotide length on the strand break cross section at various irradiation energies. The present work focuses on poly-adenine sequences (d(A₄), d(A₈), d(A₁₂), d(A₁₆), and d(A₂₀)) irradiated with 5.0, 7.0, 8.4, and 10 eV electrons. Independent of the DNA length, the strand break cross section shows a maximum around 7.0 eV electron energy for all investigated oligonucleotides confirming that strand breakage occurs through the initial formation of negative ion resonances. When going from d(A₄) to d(A₁₆), the strand break cross section increases with oligonucleotide length, but only at 7.0 and 8.4 eV, i.e., close to the maximum of the negative ion resonance, the increase in the strand break cross section with the length is similar to the increase of an estimated geometrical cross section. For d(A₂₀), a markedly lower DNA strand break cross section is observed for all electron energies, which is tentatively ascribed to a conformational change of the dA₂₀ sequence. The results indicate that, although there is a general length dependence of strand break cross sections, individual nucleotides do not contribute independently of the absolute strand break cross section of the whole DNA strand. The absolute quantification of sequence specific strand breaks will help develop a more accurate molecular level understanding of radiation induced DNA damage, which can then be used for optimized risk estimates in cancer radiation therapy.
KW  - DNA origami
KW  - DNA radiation damage
KW  - DNA strand breaks
KW  - low-energy electrons
KW  - sequence dependence
Y1  - 2019
U6  - https://doi.org/10.3390/ijms21010111
SN  - 1422-0067
VL  - 21
IS  - 1
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  - 
TY  - THES
A1  - Nacak, Selma
T1  - Synthesis and Characterization of Upconversion Nanaparticles for Applications in Life Sciences
Y1  - 2021
ER  - 
TY  - JOUR
A1  - Neffe, Axel T.
A1  - Izraylit, Victor
A1  - Hommes-Schattmann, Paul J.
A1  - Lendlein, Andreas
T1  - Soft, formstable (Co)polyester blend elastomers
JF  - Nanomaterials : open access journal
N2  - High crystallization rate and thermomechanical stability make polylactide stereocomplexes effective nanosized physical netpoints. Here, we address the need for soft, form-stable degradable elastomers for medical applications by designing such blends from (co)polyesters, whose mechanical properties are ruled by their nanodimensional architecture and which are applied as single components in implants. By careful controlling of the copolymer composition and sequence structure of poly[(L-lactide)-co-(epsilon-caprolactone)], it is possible to prepare hyperelastic polymer blends formed through stereocomplexation by adding poly(D-lactide) (PDLA). Low glass transition temperature T-g <= 0 degrees C of the mixed amorphous phase contributes to the low Young's modulus E. The formation of stereocomplexes is shown in DSC by melting transitions T-m > 190 degrees C and in WAXS by distinct scattering maxima at 2 theta = 12 degrees and 21 degrees. Tensile testing demonstrated that the blends are soft (E = 12-80 MPa) and show an excellent hyperelastic recovery R-rec = 66-85% while having high elongation at break epsilon(b) up to >1000%. These properties of the blends are attained only when the copolymer has 56-62 wt% lactide content, a weight average molar mass >140 kg center dot mol(-1), and number average lactide sequence length >= 4.8, while the blend is formed with a content of 5-10 wt% of PDLA. The devised strategy to identify a suitable copolymer for stereocomplexation and blend formation is transferable to further polymer systems and will support the development of thermoplastic elastomers suitable for medical applications.
KW  - thermoplastic elastomer
KW  - biomaterial
KW  - stereocomplexes
KW  - mechanical
KW  - properties
KW  - form stability
KW  - crystallinity
Y1  - 2021
U6  - https://doi.org/10.3390/nano11061472
SN  - 2079-4991
VL  - 11
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Bhuvanesh, Thanga
A1  - Machatschek, Rainhard Gabriel
A1  - Lysyakova, Liudmila
A1  - Kratz, Karl
A1  - Schulz, Burkhard
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Collagen type-IV Langmuir and Langmuir-Schafer layers as model biointerfaces to direct stem cell adhesion
JF  - Biomedical materials :  materials for tissue engineering and regenerative medicine
N2  - In biomaterial development, the design of material surfaces that mimic the extra-cellular matrix (ECM) in order to achieve favorable cellular instruction is rather challenging. Collagen-type IV (Col-IV), the major scaffolding component of Basement Membranes (BM), a specialized ECM with multiple biological functions, has the propensity to form networks by self-assembly and supports adhesion of cells such as endothelial cells or stem cells. The preparation of biomimetic Col-IV network-like layers to direct cell responses is difficult. We hypothesize that the morphology of the layer, and especially the density of the available adhesion sites, regulates the cellular adhesion to the layer. The Langmuir monolayer technique allows for preparation of thin layers with precisely controlled packing density at the air-water (A-W) interface. Transferring these layers onto cell culture substrates using the Langmuir-Schafer (LS) technique should therefore provide a pathway for preparation of BM mimicking layers with controlled cell adherence properties. In situ characterization using ellipsometry and polarization modulation-infrared reflection absorption spectroscopy of Col-IV layer during compression at the A-W interface reveal that there is linear increase of surface molecule concentration with negligible orientational changes up to a surface pressure of 25 mN m(-1). Smooth and homogeneous Col-IV network-like layers are successfully transferred by LS method at 15 mN m(-1) onto poly(ethylene terephthalate) (PET), which is a common substrate for cell culture. In contrast, the organization of Col-IV on PET prepared by the traditionally employed solution deposition method results in rather inhomogeneous layers with the appearance of aggregates and multilayers. Progressive increase in the number of early adherent mesenchymal stem cells (MSCs) after 24 h by controlling the areal Col-IV density by LS transfer at 10, 15 and 20 mN m(-1) on PET is shown. The LS method offers the possibility to control protein characteristics on biomaterial surfaces such as molecular density and thereby, modulate cell responses.
KW  - collagen-IV
KW  - basement membrane
KW  - Langmuir-Schafer films
KW  - stem cell adhesion
KW  - protein
KW  - ellipsometry
Y1  - 2019
U6  - https://doi.org/10.1088/1748-605X/aaf464
SN  - 1748-6041
SN  - 1748-605X
VL  - 14
IS  - 2
PB  - Inst. of Physics Publ.
CY  - Bristol
ER  - 
TY  - GEN
A1  - Ebel, Kenny
A1  - Bald, Ilko
T1  - Length and Energy Dependence of Low-Energy Electron-Induced Strand Breaks in Poly(A) DNA
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The DNA in living cells can be effectively damaged by high-energy radiation, which can lead to cell death. Through the ionization of water molecules, highly reactive secondary species such as low-energy electrons (LEEs) with the most probable energy around 10 eV are generated, which are able to induce DNA strand breaks via dissociative electron attachment. Absolute DNA strand break cross sections of specific DNA sequences can be efficiently determined using DNA origami nanostructures as platforms exposing the target sequences towards LEEs. In this paper, we systematically study the effect of the oligonucleotide length on the strand break cross section at various irradiation energies. The present work focuses on poly-adenine sequences (d(A₄), d(A₈), d(A₁₂), d(A₁₆), and d(A₂₀)) irradiated with 5.0, 7.0, 8.4, and 10 eV electrons. Independent of the DNA length, the strand break cross section shows a maximum around 7.0 eV electron energy for all investigated oligonucleotides confirming that strand breakage occurs through the initial formation of negative ion resonances. When going from d(A₄) to d(A₁₆), the strand break cross section increases with oligonucleotide length, but only at 7.0 and 8.4 eV, i.e., close to the maximum of the negative ion resonance, the increase in the strand break cross section with the length is similar to the increase of an estimated geometrical cross section. For d(A₂₀), a markedly lower DNA strand break cross section is observed for all electron energies, which is tentatively ascribed to a conformational change of the dA₂₀ sequence. The results indicate that, although there is a general length dependence of strand break cross sections, individual nucleotides do not contribute independently of the absolute strand break cross section of the whole DNA strand. The absolute quantification of sequence specific strand breaks will help develop a more accurate molecular level understanding of radiation induced DNA damage, which can then be used for optimized risk estimates in cancer radiation therapy.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 814 
KW  - DNA origami
KW  - DNA radiation damage
KW  - DNA strand breaks
KW  - low-energy electrons
KW  - sequence dependence
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-444125
SN  - 1866-8372
IS  - 814
ER  - 
TY  - JOUR
A1  - Fudickar, Werner
A1  - Roder, Phillip
A1  - Listek, Martin
A1  - Hanack, Katja
A1  - Linker, Torsten
T1  - Pyridinium alkynylanthracenes as sensitizers for photodynamic therapy
JF  - Photochemistry and photobiology
N2  - Photodynamic therapy (PDT) is a mild but effective method to treat certain types of cancer upon irradiation with visible light. Here, three isomeric methylpyridinium alkynylanthracenes 1op were evaluated as sensitizers for PDT. Upon irradiation with blue or green light, all three compounds show the ability to initiate strand breaks of plasmid DNA. The mayor species responsible for cleavage is singlet oxygen (O-1(2)) as confirmed by scavenging reagents. Only isomers 1m and 1p can be incorporated into HeLa cells, whereas isomer 1o cannot permeate through the membrane. While isomer 1m targets the cell nucleus, isomer 1p assembles in the cellular cytoplasm and impacts the cellular integrity. This is in accordance with a moderate toxicity of 1p in the dark, whereas 1m exhibits no dark toxicity. Both isomers are suitable as PDT reagents, with a CC50 of 3 mu m and 75 nm, for 1p and 1m, respectively. Thus, derivative 1m, which can be easily synthesized, becomes an interesting candidate for cancer therapy.
Y1  - 2021
U6  - https://doi.org/10.1111/php.13554
SN  - 0031-8655
SN  - 1751-1097
VL  - 98
IS  - 1
SP  - 193
EP  - 201
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - GEN
A1  - Niedl, Robert Raimund
A1  - Beta, Carsten
T1  - Hydrogel-driven paper-based microfluidics
N2  - Paper-based microfluidics provide an inexpensive, easy to use technology for point-of-care diagnostics in developing countries. Here, we combine paper-based microfluidic devices with responsive hydrogels to add an entire new class of functions to these versatile low-cost fluidic systems. The hydrogels serve as fluid reservoirs. In response to an external stimulus, e.g. an increase in temperature, the hydrogels collapse and release fluid into the structured paper substrate. In this way, chemicals that are either stored on the paper substrate or inside the hydrogel pads can be dissolved, premixed, and brought to reaction to fulfill specific analytic tasks. We demonstrate that multi-step sequences of chemical reactions can be implemented in a paper-based system and operated without the need for external precision pumps. We exemplify this technology by integrating an antibody-based E. coli test on a small and easy to use paper device.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 193 
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-81083
SP  - 2452
EP  - 2459
ER  - 
TY  - JOUR
A1  - Niedl, Robert Raimund
A1  - Beta, Carsten
T1  - Hydrogel-driven paper-based microfluidics
JF  - LAB on a chip : miniaturisation for chemistry and biology
N2  - Paper-based microfluidics provide an inexpensive, easy to use technology for point-of-care diagnostics in developing countries. Here, we combine paper-based microfluidic devices with responsive hydrogels to add an entire new class of functions to these versatile low-cost fluidic systems. The hydrogels serve as fluid reservoirs. In response to an external stimulus, e.g. an increase in temperature, the hydrogels collapse and release fluid into the structured paper substrate. In this way, chemicals that are either stored on the paper substrate or inside the hydrogel pads can be dissolved, premixed, and brought to reaction to fulfill specific analytic tasks. We demonstrate that multi-step sequences of chemical reactions can be implemented in a paper-based system and operated without the need for external precision pumps. We exemplify this technology by integrating an antibody-based E. coli test on a small and easy to use paper device.
Y1  - 2015
U6  - https://doi.org/10.1039/c5lc00276a
SN  - 1473-0197
SN  - 1473-0189
VL  - 11
IS  - 15
SP  - 2452
EP  - 2459
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Wang, Xuepu
A1  - Sperling, Marcel
A1  - Reifarth, Martin
A1  - Böker, Alexander
T1  - Shaping metallic nanolattices
BT  - Design by microcontact printing from wrinkled stamps
JF  - Small
N2  - A method for the fabrication of well-defined metallic nanostructures is presented here in a simple and straightforward fashion. As an alternative to lithographic techniques, this routine employs microcontact printing utilizing wrinkled stamps, which are prepared from polydimethylsiloxane (PDMS), and includes the formation of hydrophobic stripe patterns on a substrate via the transfer of oligomeric PDMS. Subsequent backfilling of the interspaces between these stripes with a hydroxyl-functional poly(2-vinyl pyridine) then provides the basic pattern for the deposition of citrate-stabilized gold nanoparticles promoted by electrostatic interaction. The resulting metallic nanostripes can be further customized by peeling off particles in a second microcontact printing step, which employs poly(ethylene imine) surface-decorated wrinkled stamps, to form nanolattices. Due to the independent adjustability of the period dimensions of the wrinkled stamps and stamp orientation with respect to the substrate, particle arrays on the (sub)micro-scale with various kinds of geometries are accessible in a straightforward fashion. This work provides an alternative, cost-effective, and scalable surface-patterning technique to fabricate nanolattice structures applicable to multiple types of functional nanoparticles. Being a top-down method, this process could be readily implemented into, e.g., the fabrication of optical and sensing devices on a large scale.
KW  - gold nanoparticle assembly
KW  - hydroxyl-functional poly(2-vinyl pyridine)
KW  - metallic nanolattices
KW  - microcontact printing
KW  - oligomeric
KW  - polydimethylsiloxane
KW  - polydimethylsiloxane wrinkles
KW  - wrinkled stamps
Y1  - 2020
U6  - https://doi.org/10.1002/smll.201906721
SN  - 1613-6810
SN  - 1613-6829
VL  - 16
IS  - 11
SP  - 1
EP  - 8
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - CHAP
A1  - Ramadan, Shahenda
A1  - Guerrero, Paula
A1  - Nedielkov, Ruslan
A1  - Klishin, Nikolai
A1  - Dimova, Rumiana
A1  - Silva, Daniel V.
A1  - Möller, Heiko
T1  - Building a mimetic system for unraveling protein-protein interactions on membranes
T2  - European biophysics journal : with biophysics letters ; an international journal of biophysics
Y1  - 2021
U6  - https://doi.org/10.1007/s00249-021-01558-w
SN  - 0175-7571
SN  - 1432-1017
VL  - 50
IS  - SUPPL 1
SP  - S153
EP  - S153
PB  - Springer
CY  - Berlin ; Heidelberg ; New York
ER  - 
TY  - JOUR
A1  - Piluso, Susanna
A1  - Vukicevie, Radovan
A1  - Nöchel, Ulrich
A1  - Braune, Steffen
A1  - Lendlein, Andreas
A1  - Neffe, Axel T.
T1  - Sequential alkyne-azide cycloadditions for functionalized gelatin hydrogel formation
JF  - European polymer journal
N2  - While click chemistry reactions for biopolymer network formation are attractive as the defined reactions may allow good control of the network formation and enable subsequent functionalization, tailoring of gelatin network properties over a wide range of mechanical properties has yet to be shown. Here, it is demonstrated that copper-catalyzed alkyne-azide cycloaddition of alkyne functionalized gelatin with diazides gave hydrogel networks with properties tailorable by the ratio of diazide to gelatin and diazide rigidity. 4,4′-diazido-2,2′-stilbenedisulfonic acid, which has been used as rigid crosslinker, yielded hydrogels with Young’s moduli E of 50–390 kPa and swelling degrees Q of 150–250 vol.%, while the more flexible 1,8-diazidooctane resulted in hydrogels with E = 125–280 kPa and Q = 225–470 vol.%. Storage moduli could be varied by two orders of magnitude (G′ = 100–20,000 Pa). An indirect cytotoxicity test did not show cytotoxic properties. Even when employing 1:1 ratios of alkyne and azide moieties, the hydrogels were shown to contain both, unreacted alkyne groups on the gelatin backbone as well as dangling chains carrying azide groups as shown by reaction with functionalized fluorescein. The free groups, which can be tailored by the employed ratio of the reactants, are accessible for covalent attachment of drugs, as was demonstrated by functionalization with dexamethasone. The sequential network formation and functionalization with click chemistry allows access to multifunctional materials relevant for medical applications.
KW  - Click chemistry
KW  - Hydrogel
KW  - Polymer functionalization
KW  - Biopolymer
KW  - Rheology
KW  - Multifunctionality
Y1  - 2018
U6  - https://doi.org/10.1016/j.eurpolymj.2018.01.017
SN  - 0014-3057
SN  - 1873-1945
VL  - 100
SP  - 77
EP  - 85
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Heyne, Benjamin
A1  - Arlt, Kristin
A1  - Geßner, André
A1  - Richter, Alexander F.
A1  - Döblinger, Markus
A1  - Feldmann, Jochen
A1  - Taubert, Andreas
A1  - Wedel, Armin
T1  - Mixed Mercaptocarboxylic Acid Shells Provide Stable Dispersions of InPZnS/ZnSe/ZnS Multishell Quantum Dots in Aqueous Media
JF  - Nanomaterials
N2  - Highly luminescent indium phosphide zinc sulfide (InPZnS) quantum dots (QDs), with zinc selenide/zinc sulfide (ZnSe/ZnS) shells, were synthesized. The QDs were modified via a post-synthetic ligand exchange reaction with 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) in different MPA:MUA ratios, making this study the first investigation into the effects of mixed ligand shells on InPZnS QDs. Moreover, this article also describes an optimized method for the correlation of the QD size vs. optical absorption of the QDs. Upon ligand exchange, the QDs can be dispersed in water. Longer ligands (MUA) provide more stable dispersions than short-chain ligands. Thicker ZnSe/ZnS shells provide a better photoluminescence quantum yield (PLQY) and higher emission stability upon ligand exchange. Both the ligand exchange and the optical properties are highly reproducible between different QD batches. Before dialysis, QDs with a ZnS shell thickness of ~4.9 monolayers (ML), stabilized with a mixed MPA:MUA (mixing ratio of 1:10), showed the highest PLQY, at ~45%. After dialysis, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with a mixed MPA:MUA and a ratio of 1:10 and 1:100, showed the highest PLQYs, of ~41%. The dispersions were stable up to 44 days at ambient conditions and in the dark. After 44 days, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with only MUA, showed the highest PLQY, of ~34%.
KW  - quantum dots
KW  - cadmium-free
KW  - Cd-free
KW  - InP
KW  - InPZnS
KW  - multishell
KW  - mercaptocarboxylic acids
KW  - 3-mercaptopropionic acid
KW  - 11-mercaptoundecanoic acid
KW  - phase transfer
KW  - ligand exchange
KW  - aqueous dispersion
KW  - QDs
Y1  - 2020
U6  - https://doi.org/10.3390/nano10091858
SN  - 2079-4991
VL  - 10
IS  - 9
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Tao, Lumi
A1  - Liu, Yuchuan
A1  - Wu, Dan
A1  - Wei, Qiao-Hua
A1  - Taubert, Andreas
A1  - Xie, Zailai
T1  - Luminescent Ionogels with Excellent Transparency, High Mechanical Strength, and High Conductivity
JF  - Nanomaterials
N2  - The paper describes a new kind of ionogel with both good mechanical strength and high conductivity synthesized by confining the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([Bmim][NTf₂]) within an organic–inorganic hybrid host. The organic–inorganic host network was synthesized by the reaction of methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), and methyl methacrylate (MMA) in the presence of a coupling agent, offering the good mechanical strength and rapid shape recovery of the final products. The silane coupling agent 3-methacryloxypropyltrimethoxysilane (KH-570) plays an important role in improving the mechanical strength of the inorganic–organic hybrid, because it covalently connected the organic component MMA and the inorganic component SiO₂. Both the thermal stability and mechanical strength of the ionogel significantly increased by the addition of IL. The immobilization of [Bmim][NTf₂] within the ionogel provided the final ionogel with an ionic conductivity as high as ca. 0.04 S cm⁻¹ at 50 °C. Moreover, the hybrid ionogel can be modified with organosilica-modified carbon dots within the network to yield a transparent and flexible ionogel with strong excitation-dependent emission between 400 and 800 nm. The approach is, therefore, a blueprint for the construction of next-generation multifunctional ionogels.
KW  - ionic liquid
KW  - ionogel
KW  - carbon dots
KW  - organic–inorganic hybrid
KW  - luminescence
KW  - mechanical strength
Y1  - 2020
U6  - https://doi.org/10.3390/nano10122521
SN  - 2079-4991
VL  - 10
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - GEN
A1  - Zehbe, Kerstin
A1  - Kollosche, Matthias
A1  - Lardong, Sebastian
A1  - Kelling, Alexandra
A1  - Schilde, Uwe
A1  - Taubert, Andreas
T1  - Ionogels based on poly(methyl methacrylate) and metal-containing ionic liquids
BT  - correlation between structure and mechanical and electrical properties
N2  - Ionogels (IGs) based on poly(methyl methacrylate) (PMMA) and the metal-containing ionic liquids (ILs) bis-1-butyl-3-methlimidazolium tetrachloridocuprate(II), tetrachloride cobaltate(II), and tetrachlorido manganate(II) have been synthesized and their mechanical and electrical properties have been correlated with their microstructure. Unlike many previous examples, the current IGs show a decreasing stability in stress-strain experiments on increasing IL fractions. The conductivities of the current IGs are lower than those observed in similar examples in the literature. Both effects are caused by a two-phase structure with micrometer-sized IL-rich domains homogeneously dispersed an IL-deficient continuous PMMA phase. This study demonstrates that the IL-polymer miscibility and the morphology of the IGs are key parameters to control the (macroscopic) properties of IGs.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 361 
KW  - microstructure
KW  - ionogels
KW  - ionic liquids
KW  - phase separation
KW  - mechanical properties
KW  - ionic conductivity
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-400607
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. <br /> [GRAPHICS] <br /> .
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  - GEN
A1  - Vioux, André
A1  - Taubert, Andreas
T1  - Ionic liquids 2014 and selected papers from ILMAT 2013
BT  - Highlighting the ever-growing potential of Ionic Liquids
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1055 
KW  - electrolytes
KW  - extraction
KW  - system
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-475062
SN  - 1866-8372
IS  - 1055
ER  - 
TY  - GEN
A1  - Heyne, Benjamin
A1  - Arlt, Kristin
A1  - Geßner, André
A1  - Richter, Alexander F.
A1  - Döblinger, Markus
A1  - Feldmann, Jochen
A1  - Taubert, Andreas
A1  - Wedel, Armin
T1  - Mixed Mercaptocarboxylic Acid Shells Provide Stable Dispersions of InPZnS/ZnSe/ZnS Multishell Quantum Dots in Aqueous Media
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Highly luminescent indium phosphide zinc sulfide (InPZnS) quantum dots (QDs), with zinc selenide/zinc sulfide (ZnSe/ZnS) shells, were synthesized. The QDs were modified via a post-synthetic ligand exchange reaction with 3-mercaptopropionic acid (MPA) and 11-mercaptoundecanoic acid (MUA) in different MPA:MUA ratios, making this study the first investigation into the effects of mixed ligand shells on InPZnS QDs. Moreover, this article also describes an optimized method for the correlation of the QD size vs. optical absorption of the QDs. Upon ligand exchange, the QDs can be dispersed in water. Longer ligands (MUA) provide more stable dispersions than short-chain ligands. Thicker ZnSe/ZnS shells provide a better photoluminescence quantum yield (PLQY) and higher emission stability upon ligand exchange. Both the ligand exchange and the optical properties are highly reproducible between different QD batches. Before dialysis, QDs with a ZnS shell thickness of ~4.9 monolayers (ML), stabilized with a mixed MPA:MUA (mixing ratio of 1:10), showed the highest PLQY, at ~45%. After dialysis, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with a mixed MPA:MUA and a ratio of 1:10 and 1:100, showed the highest PLQYs, of ~41%. The dispersions were stable up to 44 days at ambient conditions and in the dark. After 44 days, QDs with a ZnS shell thickness of ~4.9 ML, stabilized with only MUA, showed the highest PLQY, of ~34%.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1026 
KW  - quantum dots
KW  - cadmium-free
KW  - Cd-free
KW  - InP
KW  - InPZnS
KW  - multishell
KW  - mercaptocarboxylic acids
KW  - 3-mercaptopropionic acid
KW  - 11-mercaptoundecanoic acid
KW  - phase transfer
KW  - ligand exchange
KW  - aqueous dispersion
KW  - QDs
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-486032
SN  - 1866-8372
IS  - 1026
ER  - 
TY  - GEN
A1  - Tao, Lumi
A1  - Liu, Yuchuan
A1  - Wu, Dan
A1  - Wei, Qiao-Hua
A1  - Taubert, Andreas
A1  - Xie, Zailai
T1  - Luminescent Ionogels with Excellent Transparency, High Mechanical Strength, and High Conductivity
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The paper describes a new kind of ionogel with both good mechanical strength and high conductivity synthesized by confining the ionic liquid (IL) 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([Bmim][NTf₂]) within an organic–inorganic hybrid host. The organic–inorganic host network was synthesized by the reaction of methyltrimethoxysilane (MTMS), tetraethoxysilane (TEOS), and methyl methacrylate (MMA) in the presence of a coupling agent, offering the good mechanical strength and rapid shape recovery of the final products. The silane coupling agent 3-methacryloxypropyltrimethoxysilane (KH-570) plays an important role in improving the mechanical strength of the inorganic–organic hybrid, because it covalently connected the organic component MMA and the inorganic component SiO₂. Both the thermal stability and mechanical strength of the ionogel significantly increased by the addition of IL. The immobilization of [Bmim][NTf₂] within the ionogel provided the final ionogel with an ionic conductivity as high as ca. 0.04 S cm⁻¹ at 50 °C. Moreover, the hybrid ionogel can be modified with organosilica-modified carbon dots within the network to yield a transparent and flexible ionogel with strong excitation-dependent emission between 400 and 800 nm. The approach is, therefore, a blueprint for the construction of next-generation multifunctional ionogels.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1058 
KW  - ionic liquid
KW  - ionogel
KW  - carbon dots
KW  - organic–inorganic hybrid
KW  - luminescence
KW  - mechanical strength
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-487334
SN  - 1866-8372
IS  - 1058
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  - Bastian, Philipp U.
A1  - Robel, Nathalie
A1  - Schmidt, Peter
A1  - Schrumpf, Tim
A1  - Günter, Christina
A1  - Roddatis, Vladimir
A1  - Kumke, Michael U.
T1  - Resonance energy transfer to track the motion of lanthanide ions
BT  - what drives the intermixing in core-shell upconverting nanoparticles?
JF  - Biosensors : open access journal
N2  - The imagination of clearly separated core-shell structures is already outdated by the fact, that the nanoparticle core-shell structures remain in terms of efficiency behind their respective bulk material due to intermixing between core and shell dopant ions. In order to optimize the photoluminescence of core-shell UCNP the intermixing should be as small as possible and therefore, key parameters of this process need to be identified. In the present work the Ln(III) ion migration in the host lattices NaYF4 and NaGdF4 was monitored. These investigations have been performed by laser spectroscopy with help of lanthanide resonance energy transfer (LRET) between Eu(III) as donor and Pr(III) or Nd(III) as acceptor. The LRET is evaluated based on the Forster theory. The findings corroborate the literature and point out the migration of ions in the host lattices. Based on the introduced LRET model, the acceptor concentration in the surrounding of one donor depends clearly on the design of the applied core-shell-shell nanoparticles. In general, thinner intermediate insulating shells lead to higher acceptor concentration, stronger quenching of the Eu(III) donor and subsequently stronger sensitization of the Pr(III) or the Nd(III) acceptors. The choice of the host lattice as well as of the synthesis temperature are parameters to be considered for the intermixing process.
KW  - upconversion nanoparticles
KW  - lanthanoid migration
KW  - lanthanides
KW  - core-shell
KW  - energy transfer
Y1  - 2021
U6  - https://doi.org/10.3390/bios11120515
SN  - 2079-6374
VL  - 11
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - THES
A1  - Nie, Yan
T1  - Modulating keratinocyte and induced pluripotent stem cell behavior by microenvironment design or temperature control
N2  - Under the in vivo condition, a cell is continually interacting with its surrounding microenvironment, which is composed of its neighboring cells and the extracellular matrix (ECM). These components generate and transmit the microenvironmental signals to regulate the fate and function of the target cells. Except the signals from the microenvironment, stimuli from the ambient environment, such as temperature changes, also play an important in modulating the cell behaviors, which are considered as regulators from the macroenvironment. In this regard, recapitulation of these environmental factors to steer cell function will be of crucial importance for therapeutic purposes and tissue regeneration. Although the role of a variety of environmental factors has been evaluated, it is still challenging to identify and provide the appropriate factors, which are required for optimizing the survival of cells and for ensuring effective cell functions.
Thus, in vitro recreating the environmental factors that are present in the extracellular environment would help to understand the mechanism of how cells sense and process those environmental signals. In this context, this thesis is aimed to harness these environmental parameters to guide cell responses. Here, human induced pluripotent stem cells (hiPSCs) and human keratinocytes (KTCs), HaCaT cells, were used to investigate the impact of signals from the microenvironment or stimuli from the macroenvironment.
Firstly, polydopamine (PDA) or chitosan (CS) modifications were applied to generate different substrate surfaces for hiPSCs and KTCs (Chapter 4 to Chapter 6). Our results showed that the PDA modification was efficient to increase the cell-substrate adhesion and consequently promoted cell spreading. While CS modification was able to decrease the cell-substrate adhesion and enhance the cell-cell interaction, which enabled the morphology shift from monolayered cells to multicellular spheroids. The quantitative result was acquired using the atomic force microscopy (AFM)-based single-cell force spectroscopy. The balance between the cell-substrate and cell-cell adhesion yielded a net force, which determined the preference of the cell to adhere to its neighboring cells or to the substrate. The difference in the adhesive behaviors further affected the cellular function, such as the proliferation and differentiation potential of both hiPSCs and HaCaT cells.
Next, the cyclic temperature changes (ΔT) were selected here to study the influence of macroenvironmental stimuli on hiPSCs and KTCs (Chapter 7 and Chapter 8). The macroenvironmental temperature ranging from 10.0 ± 0.1 °C to 37.0 ± 0.1 °C was achieved using a thermal chamber equipped with a temperature controller. This temperature range was selected to explore the responses of hiPSCs to the extreme environments, while a temperature variation between 25.0 ± 0.1 °C and 37.0 ± 0.1 °C was applied to mimic the ambient temperature variations experienced by the skin epithelial KTCs. The ΔT led to cell stiffening in both hiPSCs and HaCaT cells in a cytoskeleton-dependent manner, which was measured by AFM. Specifically, in hiPSCs, the cell stiffening was resulted from the rearrangement of the actin skeleton; in HaCaT cells, was due to the difference of the Keratin (KRT) filaments. Except for inducing cell hardening, ΔT also caused differences in the protein expression profiles in hiPSCs or HaCaT cells, compared to those without ΔT treatment, which might be attributed to the alterations in their cytoskeleton structures.
To sum up, the results of the thesis demonstrated how individual factors from the micro-/macro-environment can be harnessed to modulate the behaviors of hiPSCs and HaCaT cells. Engineering the microenvironmental cues using surface modification and exploiting the macroenvironmental stimuli through temperature control were identified as precise and potent approaches to steer hiPSC and HaCaT cell behaviors. The application of AFM served as a non-invasive and real-time monitoring platform to trace the change in cell topography and mechanics induced by the environmental signals, which provide novel insights into the cell-environment interactions.
N2  - In vivo interagiert eine Zelle ständig mit ihrer Mikroumgebung, die aus ihren Nachbarzellen und der extrazellulären Matrix (ECM) besteht. Diese Komponenten erzeugen und übertragen die Mikroumgebungssignale, um das Schicksal und die Funktion der Zielzellen zu regulieren. Außer den Signalen aus der Mikroumgebung spielen auch Reize aus der Makroumgebung, wie Temperaturänderungen, eine wichtige Rolle bei der Modulation des Zellverhaltens. In dieser Hinsicht ist es wichtig, diese Umweltfaktoren zur Steuerung der Zellfunktion für therapeutische Zwecke und die Geweberegeneration zu rekapitulieren. Es stellt sich immer noch eine Herausforderung, geeignete Faktoren zu identifizieren und bereitzustellen, die zur Optimierung des Überlebens von Zellen und zur Sicherstellung effektiver Zellfunktionen erforderlich sind.
Daher würde die in vitro-Nachbildung der Umweltfaktoren helfen, den Mechanismus zu verstehen, wie Zellen diese Umweltsignale wahrnehmen und verarbeiten. In diesem Zusammenhang zielt diese Dissertation darauf ab, diese externen Parameter zu nutzen, um Zellantworten zu steuern. Hier wurden humaninduzierte pluripotente Stammzellen (hiPSCs) und humane Keratinozyten (KTCs) wie HaCaT-Zellen verwendet, um den Einfluss von Signalen aus der Mikroumgebung oder Stimuli aus der Makroumgebung zu untersuchen.
Zunächst wurden Modifikationen mit Polydopamin (PDA) oder Chitosan (CS) angewendet, um unterschiedliche Substratoberflächen für hiPSCs und KTCs zu erzeugen (Kapitel 4 bis Kapitel 6). Unsere Ergebnisse zeigten, dass die PDA-Modifikation die Zell-Substrat-Adhäsion erhöhte und folglich die Zellausbreitung förderte. Während die CS-Modifikation die Zell-Substrat-Adhäsion verringerte und die Zell-Zell-Interaktion verstärkte, verändeite sich die Morphologie von einschichtigen Zellen zu mehrzelligen Sphäroiden. Das quantitative Ergebnis wurde mittels Rasterkraftmikroskopie (AFM)-basierter Einzelzellkraftspektroskopie gewonnen. Das Gleichgewicht zwischen Zell-Substrat und Zell-Zell-Adhäsion ergab eine Nettokraft, die die Präferenz der Zelle bestimmt, an ihren Nachbarzellen oder am Substrat zu haften. Der Unterschied im Adhäsionsverhalten beeinflusste außerdem die Zellfunktion, wie das Proliferations- und Differenzierungspotential von hiPSCs und HaCaT-Zellen.
Als nächstes wurden hier zyklische Temperaturänderungen (ΔT) ausgewählt, um den Einfluss von Stimuli aus der Makroumgebung auf hiPSCs und KTCs zu untersuchen (Kapitel 7 und Kapitel 8). Die Makroumgebungstemperatur im Bereich von 10,0 ± 0,1 °C bis 37,0 ± 0,1 °C wurde unter Verwendung einer mit einem Temperaturregler ausgestatteten Wärmekammer erreicht.
Dieser Temperaturbereich wurde gewählt, um die Reaktion von hiPSCs auf extreme Umgebungen zu untersuchen, während eine Temperaturvariation zwischen 25,0 ± 0,1 ° C und 37,0 ± 0,1 ° C angewendet wurde, um die Temperaturänderungen nachzuahmen, die die Epithelzellen erfahren. Das ΔT führte zytoskelettabhängig zu einer Zellversteifung sowohl in hiPSCs als auch in HaCaT-Zellen, die mittels AFM gemessen wurde. Insbesondere bei hiPSCs resultierte die Zellversteifung aus der Neuordnung des Aktinskeletts; in HaCaT-Zellen, war auf den Unterschied der Keratin (KRT)-Filamente zurückzuführen. Abgesehen von der festgestellten Erhärtung der Zellen verursachte ΔT auch Unterschiede in den Proteinexpressionsprofilen in hiPSCs oder HaCaT-Zellen im Vergleich zu denen ohne ΔT-Behandlung. Dies könnte auf die Veränderungen in ihren Zytoskelettstrukturen zurückgeführt werden.
Zusammenfassend zeigten die Ergebnisse, wie die drei Faktoren (PDA/CS-Modifikation und ΔT) aus der Mikro-/Makroumgebung genutzt werden können, um das Verhalten von hiPSCs und HaCaT-Zellen zu modulieren. Als präzise und wirksame Ansätze zur Steuerung des hiPSC- und HaCaT-Zellen-Verhaltens wurde das Engineering der Mikroumgebungssignale durch Oberflächenmodifikation und die Nutzung der Makroumgebungsreize durch Temperaturkontrolle identifiziert. Die Anwendung von AFM diente als nicht-invasive und Echtzeit-Überwachungsplattform, um die durch die Umweltsignale induzierten Veränderungen der Zelltopographie und -mechanik zu verfolgen, die neue Einblicke in die Zell-Umwelt-Interaktionen liefern.
KW  - human induced pluripotent stem cells
KW  - human keratinocytes
KW  - cell-environment interactions
KW  - surface modification
KW  - temperature variations
KW  - humaninduzierte pluripotente Stammzellen
KW  - humane Keratinozyten
KW  - Zell-Umwelt-Interaktionen
KW  - Oberflächenmodifikation
KW  - Temperaturänderungen
Y1  - 2022
ER  - 
TY  - GEN
A1  - Sarauli, David
A1  - Xu, Chenggang
A1  - Dietzel, Birgit
A1  - Schulz, Burkhard
A1  - Lisdat, Fred
T1  - A multilayered sulfonated polyaniline network with entrapped pyrroloquinoline quinone-dependent glucose dehydrogenase
BT  - tunable direct bioelectrocatalysis
N2  - A feasible approach to construct multilayer films of sulfonated polyanilines – PMSA1 and PABMSA1 – containing different ratios of aniline, 2-methoxyaniline-5-sulfonic acid (MAS) and 3-aminobenzoic acid (AB), with the entrapped redox enzyme pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH) on Au and ITO electrode surfaces, is described. The formation of layers has been followed and confirmed by electrochemical impedance spectroscopy (EIS), which demonstrates that the multilayer assembly can be achieved in a progressive and uniform manner. The gold and ITO electrodes subsequently modified with PMSA1:PQQ-GDH and PABMSA1 films are studied by cyclic voltammetry (CV) and UV-Vis spectroscopy which show a significant direct bioelectrocatalytical response to the oxidation of the substrate glucose without any additional mediator. This response correlates linearly with the number of deposited layers. Furthermore, the constructed polymer/enzyme multilayer system exhibits a rather good long-term stability, since the catalytic current response is maintained for more than 60% of the initial value even after two weeks of storage. This verifies that a productive interaction of the enzyme embedded in the film of substituted polyaniline can be used as a basis for the construction of bioelectronic units, which are useful as indicators for processes liberating glucose and allowing optical and electrochemical transduction.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 275 
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-98744
ER  - 
TY  - JOUR
A1  - Lu, Yong-Ping
A1  - Reichetzeder, Christoph
A1  - Prehn, Cornelia
A1  - Yin, Liang-Hong
A1  - Yun, Chen
A1  - Zeng, Shufei
A1  - Chu, Chang
A1  - Adamski, Jerzy
A1  - Hocher, Berthold
T1  - Cord blood Lysophosphatidylcholine 16:1 is positively associated with birth weight
JF  - Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry and pharmacology
N2  - Background/Aims: Impaired birth outcomes, like low birth weight, have consistently been associated with increased disease susceptibility to hypertension in later life. Alterations in the maternal or fetal metabolism might impact on fetal growth and influence birth outcomes. Discerning associations between the maternal and fetal metabolome and surrogate parameters of fetal growth could give new insight into the complex relationship between intrauterine conditions, birth outcomes, and later life disease susceptibility. Methods: Using flow injection tandem mass spectrometry, targeted metabolomics was performed in serum samples obtained from 226 mother/child pairs at delivery. Associations between neonatal birth weight and concentrations of 163 maternal and fetal metabolites were analyzed. Results: After FDR adjustment using the Benjamini-Hochberg procedure lysophosphatidylcholines (LPC) 14:0, 16:1, and 18:1 were strongly positively correlated with birth weight. In a stepwise linear regression model corrected for established confounding factors of birth weight, LPC 16: 1 showed the strongest independent association with birth weight (CI: 93.63 - 168.94; P = 6.94x10(-11)). The association with birth weight was stronger than classical confounding factors such as offspring sex (CI: - 258.81- -61.32; P = 0.002) and maternal smoking during pregnancy (CI: -298.74 - -29.51; P = 0.017). Conclusions: After correction for multiple testing and adjustment for potential confounders, LPC 16:1 showed a very strong and independent association with birth weight. The underlying molecular mechanisms linking fetal LPCs with birth weight need to be addressed in future studies. (c) 2018 The Author(s) Published by S. Karger AG, Basel
KW  - Metabolomics
KW  - Lysophosphatidylcholine
KW  - Birth Weight
KW  - DOHaD
KW  - Hypertension
KW  - Type 2 Diabetes
Y1  - 2018
U6  - https://doi.org/10.1159/000487118
SN  - 1015-8987
SN  - 1421-9778
VL  - 45
IS  - 2
SP  - 614
EP  - 624
PB  - Karger
CY  - Basel
ER  - 
TY  - JOUR
A1  - Deng, Zijun
A1  - Wang, Weiwei
A1  - Xua, Xun
A1  - Gould, Oliver E. C.
A1  - Kratz, Karl
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Polymeric sheet actuators with programmable bioinstructivity
JF  - PNAS
N2  - Stem cells are capable of sensing and processing environmental inputs, converting this information to output a specific cell lineage through signaling cascades. Despite the combinatorial nature of mechanical, thermal, and biochemical signals, these stimuli have typically been decoupled and applied independently, requiring continuous regulation by controlling units. We employ a programmable polymer actuator sheet to autonomously synchronize thermal and mechanical signals applied to mesenchymal stem cells (MSC5). Using a grid on its underside, the shape change of polymer sheet, as well as cell morphology, calcium (Ca2+) influx, and focal adhesion assembly, could be visualized and quantified. This paper gives compelling evidence that the temperature sensing and mechanosensing of MSC5 are interconnected via intracellular Ca2+. Up-regulated Ca2+ levels lead to a remarkable alteration of histone H3K9 acetylation and activation of osteogenic related genes. The interplay of physical, thermal, and biochemical signaling was utilized to accelerate the cell differentiation toward osteogenic lineage. The approach of programmable bioinstructivity provides a fundamental principle for functional biomaterials exhibiting multifaceted stimuli on differentiation programs. Technological impact is expected in the tissue engineering of periosteum for treating bone defects.
KW  - reversible shape-memory actuator
KW  - mesenchymal stem cells
KW  - calcium influx
KW  - HDAC1
KW  - RUNX2
Y1  - 2020
U6  - https://doi.org/10.1073/pnas.1910668117
SN  - 1091-6490
VL  - 117
IS  - 4
SP  - 1895
EP  - 1901
PB  - National Academy of Sciences
CY  - Washington, DC
ER  - 
TY  - THES
A1  - Frieß, Fabian
T1  - Shape-memory polymer micronetworks
Y1  - 2016
ER  - 
TY  - JOUR
A1  - Lau, Skadi
A1  - Maier, Anna
A1  - Braune, Steffen
A1  - Gossen, Manfred
A1  - Lendlein, Andreas
T1  - Effect of endothelial culture medium composition on platelet responses to polymeric biomaterials
JF  - International journal of molecular sciences
N2  - Near-physiological in vitro thrombogenicity test systems for the evaluation of blood-contacting endothelialized biomaterials requires co-cultivation with platelets (PLT). However, the addition of PLT has led to unphysiological endothelial cell (EC) detachment in such in vitro systems. A possible cause for this phenomenon may be PLT activation triggered by the applied endothelial cell medium, which typically consists of basal medium (BM) and nine different supplements. To verify this hypothesis, the influence of BM and its supplements was systematically analyzed regarding PLT responses. For this, human platelet rich plasma (PRP) was mixed with BM, BM containing one of nine supplements, or with BM containing all supplements together. PLT adherence analysis was carried out in six-channel slides with plasma-treated cyclic olefin copolymer (COC) and poly(tetrafluoro ethylene) (PTFE, as a positive control) substrates as part of the six-channel slides in the absence of EC and under static conditions. PLT activation and aggregation were analyzed using light transmission aggregometry and flow cytometry (CD62P). Medium supplements had no effect on PLT activation and aggregation. In contrast, supplements differentially affected PLT adherence, however, in a polymer- and donor-dependent manner. Thus, the use of standard endothelial growth medium (BM + all supplements) maintains functionality of PLT under EC compatible conditions without masking the differences of PLT adherence on different polymeric substrates. These findings are important prerequisites for the establishment of a near-physiological in vitro thrombogenicity test system assessing polymer-based cardiovascular implant materials in contact with EC and PLT.
KW  - cyclic olefin copolymer
KW  - poly(tetrafluoroethylene)
KW  - endothelial cells
KW  - platelets
KW  - in vitro thrombogenicity testing
Y1  - 2021
U6  - https://doi.org/10.3390/ijms22137006
SN  - 1422-0067
SN  - 1661-6596
VL  - 22
IS  - 13
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  - 
TY  - GEN
A1  - Deng, Zijun
A1  - Wang, Weiwei
A1  - Xua, Xun
A1  - Gould, Oliver E. C.
A1  - Kratz, Karl
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Polymeric sheet actuators with programmable bioinstructivity
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Stem cells are capable of sensing and processing environmental inputs, converting this information to output a specific cell lineage through signaling cascades. Despite the combinatorial nature of mechanical, thermal, and biochemical signals, these stimuli have typically been decoupled and applied independently, requiring continuous regulation by controlling units. We employ a programmable polymer actuator sheet to autonomously synchronize thermal and mechanical signals applied to mesenchymal stem cells (MSC5). Using a grid on its underside, the shape change of polymer sheet, as well as cell morphology, calcium (Ca2+) influx, and focal adhesion assembly, could be visualized and quantified. This paper gives compelling evidence that the temperature sensing and mechanosensing of MSC5 are interconnected via intracellular Ca2+. Up-regulated Ca2+ levels lead to a remarkable alteration of histone H3K9 acetylation and activation of osteogenic related genes. The interplay of physical, thermal, and biochemical signaling was utilized to accelerate the cell differentiation toward osteogenic lineage. The approach of programmable bioinstructivity provides a fundamental principle for functional biomaterials exhibiting multifaceted stimuli on differentiation programs. Technological impact is expected in the tissue engineering of periosteum for treating bone defects.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1441 
KW  - reversible shape-memory actuator
KW  - mesenchymal stem cells
KW  - calcium influx
KW  - HDAC1
KW  - RUNX2
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515490
SN  - 1866-8372
IS  - 4
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  - 
TY  - JOUR
A1  - Tung, Wing Tai
A1  - Sun, Xianlei
A1  - Wang, Weiwei
A1  - Xu, Xun
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Structure, mechanical properties and degradation behavior of electrospun PEEU fiber meshes and films
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - The capability of a degradable implant to provide mechanical support depends on its degradation behavior. Hydrolytic degradation was studied for a polyesteretherurethane (PEEU70), which consists of poly(p-dioxanone) (PPDO) and poly(epsilon-caprolactone) (PCL) segments with a weight ratio of 70:30 linked by diurethane junction units. PEEU70 samples prepared in the form of meshes with average fiber diameters of 1.5 mu m (mesh1.5) and 1.2 mu m (mesh1.2), and films were sterilized and incubated in PBS at 37 degrees C with 5 vol% CO2 supply for 1 to 6 weeks. Degradation features, such as cracks or wrinkles, became apparent from week 4 for all samples. Mass loss was found to be 11 wt%, 6 wt%, and 4 wt% for mesh1.2, mesh1.5, and films at week 6. The elongation at break decreased to under 20% in two weeks for mesh1.2. In case of the other two samples, this level of degradation was achieved after 4 weeks. The weight average molecular weight of both PEEU70 mesh and film samples decreased to below 30 kg/mol when elongation at break dropped below 20%. The time period of sustained mechanical stability of PEEU70-based meshes depends on the fiber diameter and molecular weight.
Y1  - 2021
U6  - https://doi.org/10.1557/s43580-020-00001-0
SN  - 2059-8521
VL  - 6
IS  - 10
SP  - 276
EP  - 282
PB  - Springer Nature Switzerland AG
CY  - Cham
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  - Figueroa Campos, Gustavo Adolfo
A1  - Perez, Jeffrey Paulo H.
A1  - Block, Inga
A1  - Sagu Tchewonpi, Sorel
A1  - Saravia Celis, Pedro
A1  - Taubert, Andreas
A1  - Rawel, Harshadrai Manilal
T1  - Preparation of activated carbons from spent coffee and coffee parchment and assessment of their adsorbent efficiency
JF  - Processes : open access journal
N2  - The valorization of coffee wastes through modification to activated carbon has been considered as a low-cost adsorbent with prospective to compete with commercial carbons. So far, very few studies have referred to the valorization of coffee parchment into activated carbon. Moreover, low-cost and efficient activation methods need to be more investigated. The aim of this work was to prepare activated carbon from spent coffee grounds and parchment, and to assess their adsorption performance. The co-calcination processing with calcium carbonate was used to prepare the activated carbons, and their adsorption capacity for organic acids, phenolic compounds and proteins was evaluated. Both spent coffee grounds and parchment showed yields after the calcination and washing treatments of around 9.0%. The adsorption of lactic acid was found to be optimal at pH 2. The maximum adsorption capacity of lactic acid with standard commercial granular activated carbon was 73.78 mg/g, while the values of 32.33 and 14.73 mg/g were registered for the parchment and spent coffee grounds activated carbons, respectively. The Langmuir isotherm showed that lactic acid was adsorbed as a monolayer and distributed homogeneously on the surface. Around 50% of total phenols and protein content from coffee wastewater were adsorbed after treatment with the prepared activated carbons, while 44, 43, and up to 84% of hydrophobic compounds were removed using parchment, spent coffee grounds and commercial activated carbon, respectively; the adsorption efficiencies of hydrophilic compounds ranged between 13 and 48%. Finally, these results illustrate the potential valorization of coffee by-products parchment and spent coffee grounds into activated carbon and their use as low-cost adsorbent for the removal of organic compounds from aqueous solutions.
KW  - coffee by-products
KW  - spent coffee grounds
KW  - parchment
KW  - valorization
KW  - calcination
KW  - activated carbon
KW  - organic compounds adsorption
Y1  - 2021
U6  - https://doi.org/10.3390/pr9081396
SN  - 2227-9717
VL  - 9
IS  - 8
PB  - MDPI
CY  - Basel
ER  - 
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  - Tung, Wing Tai
A1  - Maring, Janita A.
A1  - Xu, Xun
A1  - Liu, Yue
A1  - Becker, Matthias
A1  - Somesh, Dipthi Bachamanda
A1  - Klose, Kristin
A1  - Wang, Weiwei
A1  - Sun, Xianlei
A1  - Ullah, Imran
A1  - Kratz, Karl
A1  - Neffe, Axel T.
A1  - Stamm, Christof
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - In vivo performance of a cell and factor free multifunctional fiber mesh modulating postinfarct myocardial remodeling
JF  - Advanced Functional Materials
N2  - Guidance of postinfarct myocardial remodeling processes by an epicardial patch system may alleviate the consequences of ischemic heart disease. As macrophages are highly relevant in balancing immune response and regenerative processes their suitable instruction would ensure therapeutic success. A polymeric mesh capable of attracting and instructing monocytes by purely physical cues and accelerating implant degradation at the cell/implant interface is designed. In a murine model for myocardial infarction the meshes are compared to those either coated with extracellular matrix or loaded with induced cardiomyocyte progenitor cells. All implants promote macrophage infiltration and polarization in the epicardium, which is verified by in vitro experiments. 6 weeks post-MI, especially the implantation of the mesh attenuates left ventricular adverse remodeling processes as shown by reduced infarct size (14.7% vs 28-32%) and increased wall thickness (854 mu m vs 400-600 mu m), enhanced angiogenesis/arteriogenesis (more than 50% increase compared to controls and other groups), and improved heart function (ejection fraction = 36.8% compared to 12.7-31.3%). Upscaling as well as process controls is comprehensively considered in the presented mesh fabrication scheme to warrant further progression from bench to bedside.
KW  - bioinstructive materials
KW  - cardiac regeneration
KW  - function by structure;
KW  - modulation of in vivo regeneration
KW  - multifunctional biomaterials
Y1  - 2022
U6  - https://doi.org/10.1002/adfm.202110179
SN  - 1616-301X
SN  - 1616-3028
VL  - 32
IS  - 31
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Sandmann, Michael
A1  - Münzberg, Marvin
A1  - Bressel, Lena
A1  - Reich, Oliver
A1  - Hass, Roland
T1  - Inline monitoring of high cell density cultivation of Scenedesmus rubescens in a mesh ultra-thin layer photobioreactor by photon density wave spectroscopy
JF  - BMC Research Notes / Biomed Central
N2  - Objective Due to multiple light scattering that occurs inside and between cells, quantitative optical spectroscopy in turbid biological suspensions is still a major challenge. This includes also optical inline determination of biomass in bioprocessing. Photon Density Wave (PDW) spectroscopy, a technique based on multiple light scattering, enables the independent and absolute determination of optical key parameters of concentrated cell suspensions, which allow to determine biomass during cultivation. Results A unique reactor type, called "mesh ultra-thin layer photobioreactor" was used to create a highly concentrated algal suspension. PDW spectroscopy measurements were carried out continuously in the reactor without any need of sampling or sample preparation, over 3 weeks, and with 10-min time resolution. Conventional dry matter content and coulter counter measurements have been employed as established offline reference analysis. The PBR allowed peak cell dry weight (CDW) of 33.4 g L-1. It is shown that the reduced scattering coefficient determined by PDW spectroscopy is strongly correlated with the biomass concentration in suspension and is thus suitable for process understanding. The reactor in combination with the fiber-optical measurement approach will lead to a better process management.
KW  - Photon density wave spectroscopy
KW  - Multiple light scattering
KW  - Process
KW  - analytical technology
KW  - Fiber-optical spectroscopy
KW  - Mesh ultra-thin layer
KW  - photobioreactor
Y1  - 2022
U6  - https://doi.org/10.1186/s13104-022-05943-2
SN  - 1756-0500
VL  - 15
IS  - 1
PB  - Biomed Central (London)
CY  - London
ER  - 
TY  - JOUR
A1  - Erler, Alexander
A1  - Riebe, Daniel
A1  - Beitz, Toralf
A1  - Löhmannsröben, Hans-Gerd
A1  - Grothusheitkamp, Daniela
A1  - Kunz, Thomas
A1  - Methner, Frank-Jürgen
T1  - Characterization of volatile metabolites formed by molds on barley by mass and ion mobility spectrometry
JF  - Journal of mass spectrometr
N2  - The contamination of barley by molds on the field or in storage leads to the spoilage of grain and the production of mycotoxins, which causes major economic losses in malting facilities and breweries. Therefore, on-site detection of hidden fungus contaminations in grain storages based on the detection of volatile marker compounds is of high interest. In this work, the volatile metabolites of 10 different fungus species are identified by gas chromatography (GC) combined with two complementary mass spectrometric methods, namely, electron impact (EI) and chemical ionization at atmospheric pressure (APCI)-mass spectrometry (MS). The APCI source utilizes soft X-radiation, which enables the selective protonation of the volatile metabolites largely without side reactions. Nearly 80 volatile or semivolatile compounds from different substance classes, namely, alcohols, aldehydes, ketones, carboxylic acids, esters, substituted aromatic compounds, alkenes, terpenes, oxidized terpenes, sesquiterpenes, and oxidized sesquiterpenes, could be identified. The profiles of volatile and semivolatile metabolites of the different fungus species are characteristic of them and allow their safe differentiation. The application of the same GC parameters and APCI source allows a simple method transfer from MS to ion mobility spectrometry (IMS), which permits on-site analyses of grain stores. Characterization of IMS yields limits of detection very similar to those of APCI-MS. Accordingly, more than 90% of the volatile metabolites found by APCI-MS were also detected in IMS. In addition to different fungus genera, different species of one fungus genus could also be differentiated by GC-IMS.
KW  - APCI
KW  - fungus
KW  - gas chromatography
KW  - ion mobility spectrometry
KW  - mass
KW  - spectrometry
KW  - mold
KW  - soft X-ray
Y1  - 2020
U6  - https://doi.org/10.1002/jms.4501
SN  - 1076-5174
SN  - 1096-9888
VL  - 55
IS  - 5
SP  - 1
EP  - 10
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Buyinza, Daniel
A1  - Derese, Solomon
A1  - Ndakala, Albert
A1  - Heydenreich, Matthias
A1  - Yenesew, Abiy
A1  - Koch, Andreas
A1  - Oriko, Richard
T1  - A coumestan and a coumaronochromone from Millettia lasiantha
JF  - Biochemical systematics and ecology
N2  - The manuscript describes the phytochemical investigation of the roots, leaves and stem bark of Millettia lasiantha resulting in the isolation of twelve compounds including two new isomeric isoflavones lascoumestan and las-coumaronochromone. The structures of the new compounds were determined using different spectroscopic techniques.
KW  - Millettia lasiantha
KW  - Leguminosae
KW  - Coumestan
KW  - Coumaronochromone
Y1  - 2021
U6  - https://doi.org/10.1016/j.bse.2021.104277
SN  - 0305-1978
SN  - 1873-2925
VL  - 97
PB  - Elsevier
CY  - Oxford
ER  -