@article{RotheZhaoMuelleretal.2021, author = {Rothe, Martin and Zhao, Yuhang and M{\"u}ller, Johannes and Kewes, G{\"u}nter and Koch, Christoph T. and Lu, Yan and Benson, Oliver}, title = {Self-assembly of plasmonic nanoantenna-waveguide structures for subdiffractional chiral sensing}, series = {ACS nano}, volume = {15}, journal = {ACS nano}, number = {1}, publisher = {American Chemical Society}, address = {Washington}, issn = {1936-0851}, doi = {10.1021/acsnano.0c05240}, pages = {351 -- 361}, year = {2021}, abstract = {Spin-momentum locking is a peculiar effect in the near-field of guided optical or plasmonic modes. It can be utilized to map the spinning or handedness of electromagnetic fields onto the propagation direction. This motivates a method to probe the circular dichroism of an illuminated chiral object. In this work, we demonstrate local, subdiffraction limited chiral coupling of light and propagating surface plasmon polaritons in a self-assembled system of a gold nanoantenna and a silver nanowire. A thin silica shell around the nanowire provides precise distance control and also serves as a host for fluorescent molecules, which indicate the direction of plasmon propagation. We characterize our nanoantenna-nanowire systems comprehensively through correlated electron microscopy, energy-dispersive X-ray spectroscopy, dark-field, and fluorescence imaging. Three-dimensional numerical simulations support the experimental findings. Besides our measurement of far-field polarization, we estimate sensing capabilities and derive not only a sensitivity of 1 mdeg for the ellipticity of the light field, but also find 10(3) deg cm(2)/dmol for the circular dichroism of an analyte locally introduced in the hot spot of the antenna-wire system. Thorough modeling of a prototypical design predicts on-chip sensing of chiral analytes. This introduces our system as an ultracompact sensor for chiral response far below the diffraction limit.}, language = {en} } @article{LauLiuMaieretal.2021, author = {Lau, Skadi and Liu, Yue and Maier, Anna and Braune, Steffen and Gossen, Manfred and Neffe, Axel T. and Lendlein, Andreas}, title = {Establishment of an in vitro thrombogenicity test system with cyclic olefin copolymer substrate for endothelial layer formation}, series = {MRS communications / a publication of the Materials Research Society}, volume = {11}, journal = {MRS communications / a publication of the Materials Research Society}, number = {5}, publisher = {Springer}, address = {Berlin}, issn = {2159-6867}, doi = {10.1557/s43579-021-00072-6}, pages = {559 -- 567}, year = {2021}, abstract = {In vitro thrombogenicity test systems require co-cultivation of endothelial cells and platelets under blood flow-like conditions. Here, a commercially available perfusion system is explored using plasma-treated cyclic olefin copolymer (COC) as a substrate for the endothelial cell layer. COC was characterized prior to endothelialization and co-cultivation with platelets under static or flow conditions. COC exhibits a low roughness and a moderate hydrophilicity. Flow promoted endothelial cell growth and prevented platelet adherence. These findings show the suitability of COC as substrate and the importance of blood flow-like conditions for the assessment of the thrombogenic risk of drugs or cardiovascular implant materials.}, language = {en} } @article{TungSunWangetal.2021, author = {Tung, Wing Tai and Sun, Xianlei and Wang, Weiwei and Xu, Xun and Ma, Nan and Lendlein, Andreas}, title = {Structure, mechanical properties and degradation behavior of electrospun PEEU fiber meshes and films}, series = {MRS advances : a journal of the Materials Research Society (MRS)}, volume = {6}, journal = {MRS advances : a journal of the Materials Research Society (MRS)}, number = {10}, publisher = {Springer Nature Switzerland AG}, address = {Cham}, issn = {2059-8521}, doi = {10.1557/s43580-020-00001-0}, pages = {276 -- 282}, year = {2021}, abstract = {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.}, language = {en} } @article{ZhaoOpitzEljarratetal.2021, author = {Zhao, Yuhang and Opitz, Andreas and Eljarrat, Alberto and Kochovski, Zdravko and Koch, Christoph and Koch, Norbert and Lu, Yan}, title = {Kinetic study on the adsorption of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane on Ag nanoparticles in chloroform}, series = {ACS applied nano materials}, volume = {4}, journal = {ACS applied nano materials}, number = {11}, publisher = {American Chemical Society}, address = {Washington}, issn = {2574-0970}, doi = {10.1021/acsanm.1c02153}, pages = {11625 -- 11635}, year = {2021}, abstract = {In this study, the kinetics of the adsorption of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F(4)TCNQ) on the surface of Ag nanoparticles (Ag NPs) in chloroform has been intensively investigated, as molecular doping is known to play a crucial role in organic electronic devices. Based on the results obtained from UV-visible (vis)-near-infrared (NIR) absorption spectroscopy, cryogenic transmission electron microscopy, scanning nanobeam electron diffraction, and electron energy loss spectroscopy, a two-step interaction kinetics has been proposed for the Ag NPs and F(4)TCNQ molecules, which includes the first step of electron transfer from Ag NPs to F(4)TCNQ indicated by the ionization of F(4)TCNQ and the second step of the formation of a Ag-F(4)TCNQ complex. The whole process has been followed via UV-vis-NIR absorption spectroscopy, which reveals distinct kinetics at two stages: the instantaneous ionization and the long-term complex formation. The kinetics and the influence of the molar ratio of Ag NPs/F(4)TCNQ molecules on the interaction between Ag NPs and F(4)TCNQ molecules in an organic solution are reported herein for the first time. Furthermore, the control experiment with silica-coated Ag NPs manifests that the charge transfer at the surface between Ag NPs and F(4)TCNQ molecules is prohibited by a silica layer of 18 nm.}, language = {en} } @article{ZhouXuMaetal.2021, author = {Zhou, Shuo and Xu, Xun and Ma, Nan and Jung, Friedrich and Lendlein, Andreas}, title = {Influence of sterilization conditions on sulfate-functionalized polyGGE}, series = {Clinical hemorheology and microcirculation : blood flow and vessels}, volume = {79}, journal = {Clinical hemorheology and microcirculation : blood flow and vessels}, number = {4}, publisher = {IOS Press}, address = {Amsterdam}, issn = {1386-0291}, doi = {10.3233/CH-211241}, pages = {597 -- 608}, year = {2021}, abstract = {Sulfated biomolecules are known to influence numerous biological processes in all living organisms. Particularly, they contribute to prevent and inhibit the hypercoagulation condition. The failure of polymeric implants and blood contacting devices is often related to hypercoagulation and microbial contamination. Here, bioactive sulfated biomacromolecules are mimicked by sulfation of poly(glycerol glycidyl ether) (polyGGE) films. Autoclaving, gamma-ray irradiation and ethylene oxide (EtO) gas sterilization techniques were applied to functionalized materials. The sulfate group density and hydrophilicity of sulfated polymers were decreased while chain mobility and thermal degradation were enhanced post autoclaving when compared to those after EtO sterilization. These results suggest that a quality control after sterilization is mandatory to ensure the amount and functionality of functionalized groups are retained.}, language = {en} } @article{BreternitzSchorr2021, author = {Breternitz, Joachim and Schorr, Susan}, title = {Symmetry relations in wurtzite nitrides and oxide nitrides and the curious case of Pmc2(1)}, series = {Acta crystallographica / International Union of Crystallography. Section A, Foundations and advances}, volume = {77}, journal = {Acta crystallographica / International Union of Crystallography. Section A, Foundations and advances}, number = {3}, publisher = {Blackwell}, address = {Oxford [u.a.]}, issn = {2053-2733}, doi = {10.1107/S2053273320015971}, pages = {208 -- 216}, year = {2021}, abstract = {Binary III-V nitrides such as AlN, GaN and InN in the wurtzite-type structure have long been considered as potent semiconducting materials because of their optoelectronic properties, amongst others. With rising concerns over the utilization of scarce elements, a replacement of the trivalent cations by others in ternary and multinary nitrides has led to the development of different variants of nitrides and oxide nitrides crystallizing in lower-symmetry variants of wurtzite. This work presents the symmetry relationships between these structural types specific to nitrides and oxide nitrides and updates some prior work on this matter. The non-existence of compounds crystallizing in Pmc2(1), formally the highest subgroup of the wurtzite type fulfilling Pauling's rules for 1:1:2 stoichiometries, has been puzzling scientists for a while; a rationalization is given, from a crystallographic basis, of why this space group is unlikely to be adopted.}, language = {en} } @article{HaubitzDrobotTsushimaetal.2021, author = {Haubitz, Toni and Drobot, Bj{\"o}rn and Tsushima, Satoru and Steudtner, Robin and Stumpf, Thorsten and Kumke, Michael Uwe}, title = {Quenching mechanism of uranyl(VI) by chloride and bromide in aqueous and non-aqueous solutions}, series = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory}, volume = {125}, journal = {The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment \& general theory}, number = {20}, publisher = {American Chemical Society}, address = {Washington}, issn = {1089-5639}, doi = {10.1021/acs.jpca.1c02487}, pages = {4380 -- 4389}, year = {2021}, abstract = {A major hindrance in utilizing uranyl(VI) luminescence as a standard analytical tool, for example, in environmental monitoring or nuclear industries, is quenching by other ions such as halide ions, which are present in many relevant matrices of uranyl(VI) speciation. Here, we demonstrate through a combination of time-resolved laser-induced fluorescence spectroscopy, transient absorption spectroscopy, and quantum chemistry that coordinating solvent molecules play a crucial role in U(VI) halide luminescence quenching. We show that our previously suggested quenching mechanism based on an internal redox reaction of the 1:2-uranyl-halide-complex holds also true for bromide-induced quenching of uranyl(VI). By adopting specific organic solvents, we were able to suppress the separation of the oxidized halide ligand X-2(center dot-) and the formed uranyl(V) into fully solvated ions, thereby "reigniting" U(VI) luminescence. Time-dependent density functional theory calculations show that quenching occurs through the outer-sphere complex of U(VI) and halide in water, while the ligand-to-metal charge transfer is strongly reduced in acetonitrile.}, language = {en} } @article{GeigerReitenbachHenscheletal.2021, author = {Geiger, Christina and Reitenbach, Julija and Henschel, Cristiane and Kreuzer, Lucas and Widmann, Tobias and Wang, Peixi and Mangiapia, Gaetano and Moulin, Jean-Fran{\c{c}}ois and Papadakis, Christine M. and Laschewsky, Andr{\´e} and M{\"u}ller-Buschbaum, Peter}, title = {Ternary nanoswitches realized with multiresponsive PMMA-b-PNIPMAM films in mixed water/acetone vapor atmospheres}, series = {Advanced engineering materials}, volume = {23}, journal = {Advanced engineering materials}, number = {11}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1438-1656}, doi = {10.1002/adem.202100191}, pages = {12}, year = {2021}, abstract = {To systematically add functionality to nanoscale polymer switches, an understanding of their responsive behavior is crucial. Herein, solvent vapor stimuli are applied to thin films of a diblock copolymer consisting of a short poly(methyl methacrylate) (PMMA) block and a long poly(N-isopropylmethacrylamide) (PNIPMAM) block for realizing ternary nanoswitches. Three significantly distinct film states are successfully implemented by the combination of amphiphilicity and co-nonsolvency effect. The exposure of the thin films to nitrogen, pure water vapor, and mixed water/acetone (90 vol\%/10 vol\%) vapor switches the films from a dried to a hydrated (solvated and swollen) and a water/acetone-exchanged (solvated and contracted) equilibrium state. These three states have distinctly different film thicknesses and solvent contents, which act as switch positions "off," "on," and "standby." For understanding the switching process, time-of-flight neutron reflectometry (ToF-NR) and spectral reflectance (SR) studies of the swelling and dehydration process are complemented by information on the local solvation of functional groups probed with Fourier-transform infrared (FTIR) spectroscopy. An accelerated responsive behavior beyond a minimum hydration/solvation level is attributed to the fast build-up and depletion of the hydration shell of PNIPMAM, caused by its hydrophobic moieties promoting a cooperative hydration character.}, language = {en} } @article{MelaniNagataSaalfrank2021, author = {Melani, Giacomo and Nagata, Yuki and Saalfrank, Peter}, title = {Vibrational energy relaxation of interfacial OH on a water-covered alpha-Al2O3(0001) surface}, series = {Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies}, volume = {23}, journal = {Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies}, number = {13}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1463-9076}, doi = {10.1039/d0cp03777j}, pages = {7714 -- 7723}, year = {2021}, abstract = {Vibrational relaxation of adsorbates is a sensitive tool to probe energy transfer at gas/solid and liquid/solid interfaces. The most direct way to study relaxation dynamics uses time-resolved spectroscopy. Here we report on a non-equilibrium ab initio molecular dynamics (NE-AIMD) methodology to model vibrational relaxation of OH vibrations on a hydroxylated, water-covered alpha-Al2O3(0001) surface. In our NE-AIMD approach, after exciting selected O-H bonds their coupling to surface phonons and to the water adlayer is analyzed in detail, by following both the energy flow in time, as well as the time-evolution of Vibrational Density of States (VDOS) curves. The latter are obtained from Time-dependent Correlation Functions (TCFs) and serve as prototypical, generic representatives of time-resolved vibrational spectra. As most important results, (i) we find a few-picosecond lifetime of the excited modes and (ii) identify both hydrogen-bonded aluminols and water molecules in the adsorbed water layer as main dissipative channels, while the direct coupling to Al2O3 surface phonons is of minor importance on the timescales of interest. Our NE-AIMD/TCF methodology is powerful for complex adsorbate systems, in principle even reacting ones, and opens a way towards time-resolved vibrational spectroscopy.}, language = {en} } @article{WangFritschBerendtsetal.2021, author = {Wang, Zhenyu and Fritsch, Daniel and Berendts, Stefan and Lerch, Martin and Breternitz, Joachim and Schorr, Susan}, title = {Elucidation of the reaction mechanism for the synthesis of ZnGeN2 through Zn2GeO4 ammonolysis}, series = {Chemical science / RSC, Royal Society of Chemistry}, volume = {12}, journal = {Chemical science / RSC, Royal Society of Chemistry}, number = {24}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2041-6539}, doi = {10.1039/d1sc00328c}, pages = {8493 -- 8500}, year = {2021}, abstract = {Ternary II-IV-N-2 materials have been considered as a promising class of materials that combine photovoltaic performance with earth-abundance and low toxicity. When switching from binary III-V materials to ternary II-IV-N-2 materials, further structural complexity is added to the system that may influence its optoelectronic properties. Herein, we present a systematic study of the reaction of Zn2GeO4 with NH3 that produces zinc germanium oxide nitrides, and ultimately approach stoichiometric ZnGeN2, using a combination of chemical analyses, X-ray powder diffraction and DFT calculations. Elucidating the reaction mechanism as being dominated by Zn and O extrusion at the later reaction stages, we give an insight into studying structure-property relationships in this emerging class of materials.}, language = {en} } @article{SaeediGarakaniXieKhorsandKheirabadetal.2021, author = {Saeedi Garakani, Sadaf and Xie, Dongjiu and Khorsand Kheirabad, Atefeh and Lu, Yan and Yuan, Jiayin}, title = {Template-synthesis of a poly(ionic liquid)-derived Fe1-xS/nitrogen-doped porous carbon membrane and its electrode application in lithium-sulfur batteries}, series = {Materials advances}, volume = {2}, journal = {Materials advances}, number = {15}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2633-5409}, doi = {10.1039/d1ma00441g}, pages = {5203 -- 5212}, year = {2021}, abstract = {This study deals with the facile synthesis of Fe1-xS nanoparticle-containing nitrogen-doped porous carbon membranes (denoted as Fe1-xS/N-PCMs) via vacuum carbonization of hybrid porous poly(ionic liquid) (PIL) membranes, and their successful use as a sulfur host material to mitigate the shuttle effect in lithium-sulfur (Li-S) batteries. The hybrid porous PIL membranes as the sacrificial template were prepared via ionic crosslinking of a cationic PIL with base-neutralized 1,1 '-ferrocenedicarboxylic acid, so that the iron source was molecularly incorporated into the template. The carbonization process was investigated in detail at different temperatures, and the chemical and porous structures of the carbon products were comprehensively analyzed. The Fe1-xS/N-PCMs prepared at 900 degrees C have a multimodal pore size distribution with a satisfactorily high surface area and well-dispersed iron sulfide nanoparticles to physically and chemically confine the LiPSs. The sulfur/Fe1-xS/N-PCM composites were then tested as electrodes in Li-S batteries, showing much improved capacity, rate performance and cycle stability, in comparison to iron sulfide-free, nitrogen-doped porous carbon membranes.}, language = {en} } @article{XuNieWangetal.2021, author = {Xu, Xun and Nie, Yan and Wang, Weiwei and Ma, Nan and Lendlein, Andreas}, title = {Periodic thermomechanical modulation of toll-like receptor expression and distribution in mesenchymal stromal cells}, series = {MRS communications / a publication of the Materials Research Society}, volume = {11}, journal = {MRS communications / a publication of the Materials Research Society}, number = {4}, publisher = {Springer}, address = {Berlin}, issn = {2159-6867}, doi = {10.1557/s43579-021-00049-5}, pages = {425 -- 431}, year = {2021}, abstract = {Toll-like receptor (TLR) can trigger an immune response against virus including SARS-CoV-2. TLR expression/distribution is varying in mesenchymal stromal cells (MSCs) depending on their culture environments. Here, to explore the effect of periodic thermomechanical cues on TLRs, thermally controlled shape-memory polymer sheets with programmable actuation capacity were created. The proportion of MSCs expressing SARS-CoV-2-associated TLRs was increased upon stimulation. The TLR4/7 colocalization was promoted and retained in the endoplasmic reticula. The TLR redistribution was driven by myosin-mediated F-actin assembly. These results highlight the potential of boosting the immunity for combating COVID-19 via thermomechanical preconditioning of MSCs.}, language = {en} } @article{DengWangXuetal.2021, author = {Deng, Zijun and Wang, Weiwei and Xu, Xun and Ma, Nan and Lendlein, Andreas}, title = {Polydopamine-based biofunctional substrate coating promotes mesenchymal stem cell migration}, series = {MRS advances : a journal of the Materials Research Society (MRS)}, volume = {6}, journal = {MRS advances : a journal of the Materials Research Society (MRS)}, number = {31}, publisher = {Springer Nature Switzerland AG}, address = {Cham}, issn = {2059-8521}, doi = {10.1557/s43580-021-00091-4}, pages = {739 -- 744}, year = {2021}, abstract = {Rapid migration of mesenchymal stem cells (MSCs) on device surfaces could support in vivo tissue integration and might facilitate in vitro organoid formation. Here, polydopamine (PDA) is explored as a biofunctional coating to effectively promote MSC motility. It is hypothesized that PDA stimulates fibronectin deposition and in this way enhances integrin-mediated migration capability. The random and directional cell migration was investigated by time-lapse microscopy and gap closure assay respectively, and analysed with softwares as computational tools. A higher amount of deposited fibronectin was observed on PDA substrate, compared to the non-coated substrate. The integrin beta 1 activation and focal adhesion kinase (FAK) phosphorylation at Y397 were enhanced on PDA substrate, but the F-actin cytoskeleton was not altered, suggesting MSC migration on PDA was regulated by integrin initiated FAK signalling. This study strengthens the biofunctionality of PDA coating for regulating stem cells and offering a way of facilitating tissue integration of devices.}, language = {en} } @article{MachatschekSaretiaLendlein2021, author = {Machatschek, Rainhard Gabriel and Saretia, Shivam and Lendlein, Andreas}, title = {Assessing the influence of temperature-memory creation on the degradation of copolyesterurethanes in ultrathin films}, series = {Advanced materials interfaces}, volume = {8}, journal = {Advanced materials interfaces}, number = {6}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2196-7350}, doi = {10.1002/admi.202001926}, pages = {8}, year = {2021}, abstract = {Copolyesterurethanes (PDLCLs) based on oligo(epsilon-caprolactone) (OCL) and oligo(omega-pentadecalactone) (OPDL) segments are biodegradable thermoplastic temperature-memory polymers. The temperature-memory capability in these polymers with crystallizable control units is implemented by a thermomechanical programming process causing alterations in the crystallite arrangement and chain organization. These morphological changes can potentially affect degradation. Initial observations on the macroscopic level inspire the hypothesis that switching of the controlling units causes an accelerated degradation of the material, resulting in programmable degradation by sequential coupling of functions. Hence, detailed degradation studies on Langmuir films of a PDLCL with 40 wt\% OPDL content are carried out under enzymatic catalysis. The temperature-memory creation procedure is mimicked by compression at different temperatures. The evolution of the chain organization and mechanical properties during the degradation process is investigated by means of polarization-modulated infrared reflection absorption spectroscopy, interfacial rheology and to some extend by X-ray reflectivity. The experiments on PDLCL Langmuir films imply that degradability is not enhanced by thermal switching, as the former depends on the temperature during cold programming. Nevertheless, the thin film experiments show that the leaching of OCL segments does not induce further crystallization of the OPDL segments, which is beneficial for a controlled and predictable degradation.}, language = {en} } @article{KreuzerWidmannGeigeretal.2021, author = {Kreuzer, Lucas and Widmann, Tobias and Geiger, Christina and Wang, Peixi and Vagias, Apostolos N. and Heger, Julian Eliah and Haese, Martin and Hildebrand, Viet and Laschewsky, Andr{\´e} and Papadakis, Christine M. and M{\"u}ller-Buschbaum, Peter}, title = {Salt-dependent phase transition behavior of doubly thermoresponsive poly(sulfobetaine)-based diblock copolymer thin films}, series = {Langmuir : the ACS journal of surfaces and colloids / American Chemical Society}, volume = {37}, journal = {Langmuir : the ACS journal of surfaces and colloids / American Chemical Society}, number = {30}, publisher = {American Chemical Society}, address = {Washington}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.1c01342}, pages = {9179 -- 9191}, year = {2021}, abstract = {The water vapor-induced swelling, as well as subsequent phase-transition kinetics, of thin films of a diblock copolymer (DBC) loaded with different amounts of the salt NaBr, is investigated in situ. In dilute aqueous solution, the DBC features an orthogonally thermoresponsive behavior. It consists of a zwitterionic poly(sulfobetaine) block, namely, poly(4-(N-(3'-methacrylamidopropyl)-N, N-dimethylammonio) butane-1-sulfonate) (PSBP), showing an upper critical solution temperature, and a nonionic block, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), exhibiting a lower critical solution temperature. The swelling kinetics in D2O vapor at 15 degrees C and the phase transition kinetics upon heating the swollen film to 60 degrees C and cooling back to 15 degrees C are followed with simultaneous time-of-flight neutron reflectometry and spectral reflectance measurements. These are complemented by Fourier transform infrared spectroscopy. The collapse temperature of PNIPMAM and the swelling temperature of PSBP are found at lower temperatures than in aqueous solution, which is attributed to the high polymer concentration in the thin-film geometry. Upon inclusion of sub-stoichiometric amounts (relative to the monomer units) of NaBr in the films, the water incorporation is significantly increased. This increase is mainly attributed to a salting-in effect on the zwitterionic PSBP block. Whereas the addition of NaBr notably shifts the swelling temperature of PSBP to lower temperatures, the collapse temperature of PNIPMAM remains unaffected by the presence of salt in the films.}, language = {en} } @article{NeffeLoewenbergJulichGruneretal.2021, author = {Neffe, Axel T. and L{\"o}wenberg, Candy and Julich-Gruner, Konstanze K. and Behl, Marc and Lendlein, Andreas}, title = {Thermally-induced shape-memory behavior of degradable gelatin-based networks}, series = {International journal of molecular sciences}, volume = {22}, journal = {International journal of molecular sciences}, number = {11}, publisher = {Molecular Diversity Preservation International}, address = {Basel}, issn = {1422-0067}, doi = {10.3390/ijms22115892}, pages = {15}, year = {2021}, abstract = {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.}, language = {en} } @article{BochoveGrijpmaLendleinetal.2021, author = {Bochove, Bas van and Grijpma, Dirk W. and Lendlein, Andreas and Sepp{\"a}l{\"a}, Jukka}, title = {Designing advanced functional polymers for medicine}, series = {European polymer journal : EPJ}, volume = {155}, journal = {European polymer journal : EPJ}, publisher = {Elsevier}, address = {Oxford}, issn = {0014-3057}, doi = {10.1016/j.eurpolymj.2021.110573}, pages = {2}, year = {2021}, language = {en} } @article{HwangZhangYouketal.2021, author = {Hwang, Jinyeon and Zhang, Wuyong and Youk, Sol and Schutjajew, Konstantin and Oschatz, Martin}, title = {Understanding structure-property relationships under experimental conditions for the optimization of lithium-ion capacitor anodes based on all-carbon-composite materials}, series = {Energy technology : generation, conversion, storage, distribution}, volume = {9}, journal = {Energy technology : generation, conversion, storage, distribution}, number = {3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2194-4296}, doi = {10.1002/ente.202001054}, pages = {8}, year = {2021}, abstract = {The nanoscale combination of a conductive carbon and a carbon-based material with abundant heteroatoms for battery electrodes is a method to overcome the limitation that the latter has high affinity to alkali metal ions but low electronic conductivity. The synthetic protocol and the individual ratios and structures are important aspects influencing the properties of such multifunctional compounds. Their interplay is, herein, investigated by infiltration of a porous ZnO-templated carbon (ZTC) with nitrogen-rich carbon obtained by condensation of hexaazatriphenylene-hexacarbonitrile (HAT-CN) at 550-1000 degrees C. The density of lithiophilic sites can be controlled by HAT-CN content and condensation temperature. Lithium storage properties are significantly improved in comparison with those of the individual compounds and their physical mixtures. Depending on the uniformity of the formed composite, loading ratio and condensation temperature have different influence. Most stable operation at high capacity per used monomer is achieved with a slowly dried composite with an HAT-CN:ZTC mass ratio of 4:1, condensed at 550 degrees C, providing more than 400 mAh g(-1) discharge capacity at 0.1 A g(-1) and a capacity retention of 72\% after 100 cycles of operation at 0.5 A g(-1) due to the homogeneity of the composite and high content of lithiophilic sites.}, language = {en} } @article{KreuzerLindenmeirGeigeretal.2021, author = {Kreuzer, Lucas and Lindenmeir, Christoph and Geiger, Christina and Widmann, Tobias and Hildebrand, Viet and Laschewsky, Andr{\´e} and Papadakis, Christine M. and M{\"u}ller-Buschbaum, Peter}, title = {Poly(sulfobetaine) versus poly(N-isopropylmethacrylamide)}, series = {Macromolecules : a publication of the American Chemical Society}, volume = {54}, journal = {Macromolecules : a publication of the American Chemical Society}, number = {3}, publisher = {American Chemical Society}, address = {Washington}, issn = {0024-9297}, doi = {10.1021/acs.macromol.0c02281}, pages = {1548 -- 1556}, year = {2021}, abstract = {The swelling and co-nonsolvency behaviors in pure H2O and in a mixed H2O/CH3OH vapor atmosphere of two different polar, water-soluble polymers in thin film geometry are studied in situ. Films of a zwitterionic poly(sulfobetaine), namely, poly[3-((2-(methacryloyloxy)ethyl)dimethylammonio) propane-1-sulfonate] (PSPE), and a polar nonionic polymer, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), are investigated in real time by spectral reflectance (SR) measurements and Fourier transform infrared (FTIR) spectroscopy. Whereas PSPE is insoluble in methanol, PNIPMAM is soluble but exhibits cononsolvency behavior in water/methanol mixtures. First, the swelling of PSPE and PNIPMAM thin films in H2O vapor is followed. Subsequently, CH3OH is added to the vapor atmosphere, and its contracting effect on the water-swollen films is monitored, revealing a co-nonsolvency-type behavior for PNIPMAM and PSPE. SR measurements indicate that PSPE and PNIPMAM behave significantly different during the H2O swelling and subsequent exposure to CH3OH, not only with respect to the amounts of absorbed water and CH3OH, but also to the cosolvent-induced contraction mechanisms. While PSPE thin films exhibit an abrupt one-step contraction, the contraction of PNIPMAM thin films occurs in two steps. FTIR studies corroborate these findings on a molecular scale and reveal the role of the specific functional groups, both during the swelling and the cosolvent-induced switching of the solvation state.}, language = {en} } @article{SaretiaMachatschekLendlein2021, author = {Saretia, Shivam and Machatschek, Rainhard Gabriel and Lendlein, Andreas}, title = {Degradation kinetics of oligo(ε-caprolactone) ultrathin films}, series = {MRS advances : a journal of the Materials Research Society (MRS)}, volume = {6}, journal = {MRS advances : a journal of the Materials Research Society (MRS)}, number = {33}, publisher = {Springer Nature Switzerland AG}, address = {Cham}, issn = {2059-8521}, doi = {10.1557/s43580-021-00067-4}, pages = {790 -- 795}, year = {2021}, abstract = {The potential of using crystallinity as morphological parameter to control polyester degradation in acidic environments is explored in ultrathin films by Langmuir technique. Films of hydroxy or methacrylate end-capped oligo(epsilon-caprolactone) (OCL) are prepared at the air-water interface as a function of mean molecular area (MMA). The obtained amorphous, partially crystalline or highly crystalline ultrathin films of OCL are hydrolytically degraded at pH similar to 1.2 on water surface or on silicon surface as-transferred films. A high crystallinity reduces the hydrolytic degradation rate of the films on both water and solid surfaces. Different acceleration rates of hydrolytic degradation of semi-crystalline films are achieved either by crystals complete melting, partially melting, or by heating them below their melting temperatures. Semi-crystalline OCL films transferred via water onto a solid surface retain their crystalline morphology, degrade in a controlled manner, and are of interest as thermoswitchable coatings for cell substrates and medical devices.}, language = {en} } @article{FolikumahBehlLendlein2021, author = {Folikumah, Makafui Y. and Behl, Marc and Lendlein, Andreas}, title = {Reaction behaviour of peptide-based single thiol-thioesters exchange reaction substrate in the presence of externally added thiols}, series = {MRS communications / a publication of the Materials Research Society}, volume = {11}, journal = {MRS communications / a publication of the Materials Research Society}, number = {4}, publisher = {Springer}, address = {Berlin}, issn = {2159-6859}, doi = {10.1557/s43579-021-00041-z}, pages = {402 -- 410}, year = {2021}, abstract = {Identification of patterns in chemical reaction pathways aids in the effective design of molecules for specific applications. Here, we report on model reactions with a water-soluble single thiol-thioester exchange (TTE) reaction substrate, which was designed taking in view biological and medical applications. This substrate consists of the thio-depsipeptide, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH (TDP) and does not yield foul-smelling thiol exchange products when compared with aromatic thiol containing single TTE substrates. TDP generates an alpha,omega-dithiol crosslinker in situ in a 'pseudo intramolecular' TTE. Competitive intermolecular TTE of TDP with externally added "basic" thiols increased the crosslinker concentration whilst "acidic" thiols decreased its concentration. TDP could potentially enable in situ bioconjugation and crosslinking applications.}, language = {en} } @article{KleinpeterHeydenreichShainyan2021, author = {Kleinpeter, Erich and Heydenreich, Matthias and Shainyan, Bagrat A.}, title = {At the experimental limit of the NMR conformational analysis}, series = {Organic letters}, volume = {23}, journal = {Organic letters}, number = {2}, publisher = {American Chemical Society}, address = {Washington}, issn = {1523-7060}, doi = {10.1021/acs.orglett.0c03878}, pages = {405 -- 409}, year = {2021}, abstract = {The low temperature (95 K) NMR study of 1-Ph-1-t-Bu-silacyclohexane (1) showed the conformational equilibrium to be extremely one-sided toward thePh(ax),t-Bueq conformer. The barrier to interconversion has been measured (4.2-4.6 kcal/mol) and the conformational equilibrium [Delta nu = 1990.64 ppm (Si-29), 618.9 ppm (C-13), 1-Ph-ax:1-Pheq = (95.6-96.6\%):(3.4-4.4\%), K = 25 +/- 3, Delta G degrees = -RT ln K = 0.58-0.63 kcal/mol] analyzed. The assignment and quantification of the NMR signals is supported by MP2 and DFT calculations.}, language = {en} } @article{MawireMozirandiHeydenreichetal.2021, author = {Mawire, Phillip and Mozirandi, Winnie and Heydenreich, Matthias and Chi, Godloves Fru and Mukanganyama, Stanley}, title = {Isolation and antimicrobial activities of phytochemicals from Parinari curatellifolia (Chrysobalanaceae)}, series = {Advances in pharmacological and pharmaceutical sciences}, journal = {Advances in pharmacological and pharmaceutical sciences}, publisher = {Hindawi}, address = {London}, issn = {2633-4682}, doi = {10.1155/2021/8842629}, pages = {18}, year = {2021}, abstract = {The widespread use of antimicrobial agents to treat infectious diseases has led to the emergence of antibiotic resistant pathogens. Plants have played a central role in combating many ailments in humans, and Parinari curatellifolia has been used for medicinal purposes. Seven extracts from P. curatellifolia leaves were prepared using serial exhaustive extraction of nonpolar to polar solvents. The microbroth dilution method was used to evaluate antimicrobial bioactivities of extracts. Five of the extracts were significantly active against at least one test microbe. Mycobacterium smegmatis was the most susceptible to most extracts. The methanol and ethanol extracts were the most active against M. smegmatis with an MIC of 25 mu g/mL. The hexane extract was the most active against Candida krusei with an MIC of 25 mu g/mL. None of the extracts significantly inhibited growth of Klebsiella pneumoniae and Staphylococcus aureus. Active extracts were selected for fractionation and isolation of pure compounds using gradient elution column chromatography. TLC analyses was carried out for pooling fractions of similar profiles. A total of 43 pools were obtained from 428 fractions. Pools 7 and 10 were selected for further isolation of single compounds. Four compounds, Pc4963r, Pc4962w, Pc6978p, and Pc6978o, were isolated. Evaluation of antimicrobial activities of Pc4963r, Pc4962w, and Pc6978p showed that the compounds were most active against C. krusei with MFC values ranging from 50 to 100 mu g/mL. Only Pc6978p was shown to be pure. Using spectroscopic analyses, the structure of Pc6978p was determined to be beta-sitosterol. The antifungal effects of beta-sitosterol were evaluated against C. krusei in vitro and on fabrics. Results showed that beta-sitosterol reduced the growth of C. krusei attached to Mendy fabric by 83\%. Therefore, P. curatellifolia can be a source of lead compounds for prospective development of novel antimicrobial agents. Further work needs to be done to improve the antifungal activity of the isolated compound using quantitative structure-activity relationships.}, language = {en} } @article{BekirJelkenJungetal.2021, author = {Bekir, Marek and Jelken, Joachim and Jung, Se-Hyeong and Pich, Andrij and Pacholski, Claudia and Kopyshev, Alexey and Santer, Svetlana}, title = {Dual responsiveness of microgels induced by single light stimulus}, series = {Applied physics letters}, volume = {118}, journal = {Applied physics letters}, number = {9}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0003-6951}, doi = {10.1063/5.0036376}, pages = {6}, year = {2021}, abstract = {We report on the multiple response of microgels triggered by a single optical stimulus. Under irradiation, the volume of the microgels is reversibly switched by more than 20 times. The irradiation initiates two different processes: photo-isomerization of the photo-sensitive surfactant, which forms a complex with the anionic microgel, rendering it photo-responsive; and local heating due to a thermo-plasmonic effect within the structured gold layer on which the microgel is deposited. The photo-responsivity is related to the reversible accommodation/release of the photo-sensitive surfactant depending on its photo-isomerization state, while the thermo-sensitivity is intrinsically built in. We show that under exposure to green light, the thermo-plasmonic effect generates a local hot spot in the gold layer, resulting in the shrinkage of the microgel. This process competes with the simultaneous photo-induced swelling. Depending on the position of the laser spot, the spatiotemporal control of reversible particle shrinking/swelling with a predefined extent on a per-second base can be implemented.}, language = {en} } @article{NeffeLoewenbergLendlein2021, author = {Neffe, Axel T. and L{\"o}wenberg, Candy and Lendlein, Andreas}, title = {Hydrogel networks by aliphatic dithiol Michael addition to glycidylmethacrylated gelatin}, series = {MRS advances : a journal of the Materials Research Society (MRS)}, volume = {6}, journal = {MRS advances : a journal of the Materials Research Society (MRS)}, number = {33}, publisher = {Springer Nature Switzerland AG}, address = {Cham}, issn = {2059-8521}, doi = {10.1557/s43580-021-00136-8}, pages = {796 -- 800}, year = {2021}, abstract = {Functionalization of gelatin with glycidylmethacrylate (GMA-gelatin) enables network formation employing the double bond, so that the reaction is orthogonal to the inherent functional groups in the biomacromolecule. Here, network formation by crosslinking of GMA-gelatin with hexane 1,6-dithiol or nonane 1,9-dithiol to tailor properties and enable a shape-memory effect is shown by H-1 NMR and FT-IR spectroscopy. Hydrogel swelling (460-1900 vol\%) and mechanical properties (Young's modulus E = 59-512 kPa, elongation at break epsilon(b) = 44-127\%) depended on the molecular composition of the networks and temperature. Increased crosslinker length, thiol:methacrylate molar ratio, and precursor concentrations led to denser networks. Change of properties with temperature suggested adoption of triple helices by gelatin chains, forming physical netpoints at lower temperatures (< 20 degrees C). However, the limited freedom of the gelatin chains to move allowed only a minimal extent of triple helices formation, as it became apparent from the related signal in wide-angle X-ray scattering and the thermal transition associated to triple helices in some networks by DSC. The presented strategy is likely transferable to other biomacromolecules, and the results suggest that too short crosslinkers may result in a significant amount of grafting rather than network formation.}, language = {en} } @article{LauMaierBrauneetal.2021, author = {Lau, Skadi and Maier, Anna and Braune, Steffen and Gossen, Manfred and Lendlein, Andreas}, title = {Effect of endothelial culture medium composition on platelet responses to polymeric biomaterials}, series = {International journal of molecular sciences}, volume = {22}, journal = {International journal of molecular sciences}, number = {13}, publisher = {Molecular Diversity Preservation International}, address = {Basel}, issn = {1422-0067}, doi = {10.3390/ijms22137006}, pages = {13}, year = {2021}, abstract = {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.}, language = {en} } @article{SchoenemannKocKarthaeuseretal.2021, author = {Sch{\"o}nemann, Eric and Koc, Julian and Karth{\"a}user, Jana and {\"O}zcan, Onur and Schanzenbach, Dirk and Schardt, Lisa and Rosenhahn, Axel and Laschewsky, Andr{\´e}}, title = {Sulfobetaine methacrylate polymers of unconventional polyzwitterion architecture and their antifouling properties}, series = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, volume = {22}, journal = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, number = {4}, publisher = {American Chemical Society}, address = {Washington}, issn = {1525-7797}, doi = {10.1021/acs.biomac.0c01705}, pages = {1494 -- 1508}, year = {2021}, abstract = {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.}, language = {en} } @article{IhlenburgMaiThuenemannetal.2021, author = {Ihlenburg, Ramona and Mai, Tobias and Th{\"u}nemann, Andreas F. and Baerenwald, Ruth and Saalw{\"a}chter, Kay and Koetz, Joachim and Taubert, Andreas}, title = {Sulfobetaine hydrogels with a complex multilength-scale hierarchical structure}, series = {The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces \& biophysical chemistry}, volume = {125}, journal = {The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces \& biophysical chemistry}, number = {13}, publisher = {American Chemical Society}, address = {Washington}, issn = {1520-6106}, doi = {10.1021/acs.jpcb.0c10601}, pages = {3398 -- 3408}, year = {2021}, abstract = {Hydrogels with a hierarchical structure were prepared from a new highly water-soluble crosslinker N,N,N',N'-tetramethyl-N,N'-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and from the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The free radical polymerization of the two compounds is rapid and yields near-transparent hydrogels with sizes up to 5 cm in diameter. Rheology shows a clear correlation between the monomer-to-crosslinker ratio and the storage and loss moduli of the hydrogels. Cryo-scanning electron microscopy, low-field nuclear magnetic resonance (NMR) spectroscopy, and small-angle X-ray scattering show that the gels have a hierarchical structure with features spanning the nanometer to the sub-millimeter scale. The NMR study is challenged by the marked inhomogeneity of the gels and the complex chemical structure of the sulfobetaine monomer. NMR spectroscopy shows how these complications can be addressed via a novel fitting approach that considers the mobility gradient along the side chain of methacrylate-based monomers.}, language = {en} } @article{ZhangRešetičBehletal.2021, author = {Zhang, Pengfei and Rešetič, Andraž and Behl, Marc and Lendlein, Andreas}, title = {Multifunctionality in polymer networks by dynamic of coordination bonds}, series = {Macromolecular chemistry and physics}, volume = {222}, journal = {Macromolecular chemistry and physics}, number = {3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-3935}, doi = {10.1002/macp.202000394}, pages = {11}, year = {2021}, abstract = {The need for multifunctional materials is driven by emerging technologies and innovations, such as in the field of soft robotics and tactile or haptic systems, where minimizing the number of operational components is not only desirable, but can also be essential for realizing such devices. This study report on designing a multifunctional soft polymer material that can address a number of operating requirements such as solvent resistance, reshaping ability, self-healing capability, fluorescence stimuli-responsivity, and anisotropic structural functions. The numerous functional abilities are associated to rhodium(I)-phosphine coordination bonds, which in a polymer network act with their dynamic and non-covalently bonded nature as multifunctional crosslinks. Reversible aggregation of coordination bonds leads to changes in fluorescence emission intensity that responds to chemical or mechanical stimuli. The fast dynamics and diffusion of rhodium-phosphine ions across and through contacting areas of the material provide for reshaping and self-healing abilities that can be further exploited for assembly of multiple pieces into complex forms, all without any loss to material-sensing capabilities.}, language = {en} } @article{MachatschekHeuchelLendlein2021, author = {Machatschek, Rainhard Gabriel and Heuchel, Matthias and Lendlein, Andreas}, title = {Hydrolytic stability of polyetherimide investigated in ultrathin films}, series = {Journal of materials research : JMR / Materials Research Society}, volume = {36}, journal = {Journal of materials research : JMR / Materials Research Society}, number = {14}, publisher = {Springer}, address = {Berlin}, issn = {0884-2914}, doi = {10.1557/s43578-021-00267-6}, pages = {2987 -- 2994}, year = {2021}, abstract = {Increasing the surface hydrophilicity of polyetherimide (PEI) through partial hydrolysis of the imide groups while maintaining the length of the main-chain was explored for adjusting its function in biomedical and membrane applications. The outcome of the polymer analogous reaction, i.e., the degree of ring opening and chain cleavage, is difficult to address in bulk and microstructured systems, as these changes only occur at the interface. Here, the reaction was studied at the air-water interface using the Langmuir technique, assisted by atomic force microscopy and vibrational spectroscopy. Slow PEI hydrolysis sets in at pH > 12. At pH = 14, the ring opening is nearly instantaneous. Reduction of the layer viscosity with time at pH = 14 suggested moderate chain cleavage. No hydrolysis was observed at pH = 1. Hydrolyzed PEI films had a much more cohesive structure, suggesting that the nanoporous morphology of PEI can be tuned via hydrolysis.}, language = {en} } @article{MachatschekHeuchelLendlein2021, author = {Machatschek, Rainhard Gabriel and Heuchel, Matthias and Lendlein, Andreas}, title = {Thin-layer studies on surface functionalization of polyetherimide}, series = {Journal of materials research : JMR / Materials Research Society}, volume = {37}, journal = {Journal of materials research : JMR / Materials Research Society}, number = {1}, publisher = {Springer}, address = {Berlin}, issn = {0884-2914}, doi = {10.1557/s43578-021-00339-7}, pages = {67 -- 76}, year = {2021}, abstract = {Among the high-performance and engineering polymers, polyimides and the closely related polyetherimide (PEI) stand out by their capability to react with nucleophiles under relatively mild conditions. By targeting the phthalimide groups in the chain backbone, post-functionalization offers a pathway to adjust surface properties such as hydrophilicity, solvent resistance, and porosity. Here, we use ultrathin PEI films on a Langmuir trough as a model system to investigate the surface functionalization with ethylene diamine and tetrakis(4-aminophenyl)porphyrin as multivalent nucleophiles. By means of AFM, Raman spectroscopy, and interfacial rheology, we show that hydrolysis enhances the chemical and mechanical stability of ultrathin films and allows for the formation of EDC/NHS-activated esters. Direct amidation of PEI was achieved in the presence of a Lewis acid catalyst, resulting in free amine groups rather than cross-linking. When comparing amidation with hydrolysis, we find a greater influence of the latter on material properties.}, language = {en} } @article{BuyinzaDereseNdakalaetal.2021, author = {Buyinza, Daniel and Derese, Solomon and Ndakala, Albert and Heydenreich, Matthias and Yenesew, Abiy and Koch, Andreas and Oriko, Richard}, title = {A coumestan and a coumaronochromone from Millettia lasiantha}, series = {Biochemical systematics and ecology}, volume = {97}, journal = {Biochemical systematics and ecology}, publisher = {Elsevier}, address = {Oxford}, issn = {0305-1978}, doi = {10.1016/j.bse.2021.104277}, pages = {5}, year = {2021}, abstract = {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.}, language = {en} } @article{GharabekyanKoetzPoghosyan2021, author = {Gharabekyan, Hrant H. and Koetz, Joachim and Poghosyan, Armen H.}, title = {A protonated L-cysteine adsorption on gold surface}, series = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects}, volume = {629}, journal = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2021.127452}, pages = {7}, year = {2021}, abstract = {The adsorption of protonated L-cysteine onto Au(111) surface was studied via molecular dynamics method. The detailed examination of trajectories reveals that a couple of picoseconds need to be strongly adsorbed at the gold surface via L-cysteine's sulfur and oxygen atoms. The average distances of L-cysteine's adsorbed sulfur and oxygen from gold plane are-2.7 angstrom and-3.2 angstrom, correspondingly. We found that the adsorption of L-cysteine takes place preferentially at bridge site with possibility of-82\%. Discussing the conformation features of protonated L-cysteine, we consider that the most stable conformation of protonated L-cysteine is "reverse boat" position, where sulfur and oxygen pointed down to the gold surface, while the amino group is far from the gold surface.}, language = {en} } @article{BouaklineSaalfrank2021, author = {Bouakline, Foudhil and Saalfrank, Peter}, title = {Seemingly asymmetric atom-localized electronic densities following laser-dissociation of homonuclear diatomics}, series = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry}, volume = {154}, journal = {The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry}, number = {23}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0021-9606}, doi = {10.1063/5.0049710}, pages = {10}, year = {2021}, abstract = {Recent experiments on laser-dissociation of aligned homonuclear diatomic molecules show an asymmetric forward-backward (spatial) electron-localization along the laser polarization axis. Most theoretical models attribute this asymmetry to interference effects between gerade and ungerade vibronic states. Presumably due to alignment, these models neglect molecular rotations and hence infer an asymmetric (post-dissociation) charge distribution over the two identical nuclei. In this paper, we question the equivalence that is made between spatial electron-localization, observed in experiments, and atomic electron-localization, alluded by these theoretical models. We show that (seeming) agreement between these models and experiments is due to an unfortunate omission of nuclear permutation symmetry, i.e., quantum statistics. Enforcement of the latter requires mandatory inclusion of the molecular rotational degree of freedom, even for perfectly aligned molecules. Unlike previous interpretations, we ascribe spatial electron-localization to the laser creation of a rovibronic wavepacket that involves field-free molecular eigenstates with opposite space-inversion symmetry i.e., even and odd parity. Space-inversion symmetry breaking would then lead to an asymmetric distribution of the (space-fixed) electronic density over the forward and backward hemisphere. However, owing to the simultaneous coexistence of two indistinguishable molecular orientational isomers, our analytical and computational results show that the post-dissociation electronic density along a specified space-fixed axis is equally shared between the two identical nuclei-a result that is in perfect accordance with the principle of the indistinguishability of identical particles. Published under an exclusive license by AIP Publishing.}, language = {en} } @article{QiuZhangBicketal.2021, author = {Qiu, Liang and Zhang, Haoran and Bick, Thomas and Martin, Johannes and Wendler, Petra and B{\"o}ker, Alexander and Glebe, Ulrich and Xing, Chengfen}, title = {Construction of highly ordered glyco-inside nano-assemblies through RAFT dispersion polymerization of galactose-decorated monomer}, series = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, volume = {60}, journal = {Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition}, number = {20}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1433-7851}, doi = {10.1002/anie.202015692}, pages = {11098 -- 11103}, year = {2021}, abstract = {Glyco-assemblies derived from amphiphilic sugar-decorated block copolymers (ASBCs) have emerged prominently due to their wide application, for example, in biomedicine and as drug carriers. However, to efficiently construct these glyco-assemblies is still a challenge. Herein, we report an efficient technology for the synthesis of glyco-inside nano-assemblies by utilizing RAFT polymerization of a galactose-decorated methacrylate for polymerization-induced self-assembly (PISA). Using this approach, a series of highly ordered glyco-inside nano-assemblies containing intermediate morphologies were fabricated by adjusting the length of the hydrophobic glycoblock and the polymerization solids content. A specific morphology of complex vesicles was captured during the PISA process and the formation mechanism is explained by the morphology of its precursor and intermediate. Thus, this method establishes a powerful route to fabricate glyco-assemblies with tunable morphologies and variable sizes, which is significant to enable the large-scale fabrication and wide application of glyco-assemblies.}, language = {en} } @article{SperlichKoeckerling2021, author = {Sperlich, Eric and K{\"o}ckerling, Martin}, title = {Cluster salts [Nb6Cl12(HIm)(6)]A(n) (with HIm=1H-imidazole and A=Mineral Acid Anion, n=1 or 2) made in and with Bronsted-basic ionic liquids and liquid mixtures}, series = {ChemistryOpen}, volume = {10}, journal = {ChemistryOpen}, number = {2}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2191-1363}, doi = {10.1002/open.202000266}, pages = {248 -- 254}, year = {2021}, abstract = {Four new hexanuclear niobium cluster compounds of the general formula [Nb6Cl12(HIm)(6)](A)(n) . x(solvent molecule) (HIm=1H-imidazole, A=mineral acid anion, Cl- (n=2) (1), (SO4)(2-) (n=1) (2), (CrO4)(2-) (n=1) (3), and (HAsO4)(2-) (n=1) (4)) were prepared. Their synthesis can be done in basic ionic liquids, which form on the addition of a mineral acid, which also delivers the counter anion for the final cluster compound, to an excess of the 1H-imidazole. Some addition of an auxiliary solvent, like methanol, improves the speed of crystallisation. The cluster unit comprises a hexanuclear Nb-6 unit of octahedral shape with the edges bridged by Cl atoms and the exo sites being occupied by N-bonded 1H-imidazole ligands. The cluster cation carries sixteen cluster-based electrons. Between the NH groups of the ligands of the cluster unit, the anions and the co-crystallised water (1), or 1H-imidazole and methanol molecules (2, 3, and 4) a network of hydrogen bonds exists.}, language = {en} } @article{AkarsuGrobeNowaczyketal.2021, author = {Akarsu, Pinar and Grobe, Richard and Nowaczyk, Julius and Hartlieb, Matthias and Reinicke, Stefan and B{\"o}ker, Alexander and Sperling, Marcel and Reifarth, Martin}, title = {Solid-phase microcontact printing for precise patterning of rough surfaces}, series = {ACS applied polymer materials}, volume = {3}, journal = {ACS applied polymer materials}, number = {5}, publisher = {American Chemical Society}, address = {Washington}, issn = {2637-6105}, doi = {10.1021/acsapm.1c00024}, pages = {2420 -- 2431}, year = {2021}, abstract = {We present a microcontact printing (mu CP) routine suitable to introduce defined (sub-) microscale patterns on surface substrates exhibiting a high capillary activity and receptive to a silane-based chemistry. This is achieved by transferring functional trivalent alkoxysilanes, such as (3-aminopropyl)-triethoxysilane (APTES) as a low-molecular weight ink via reversible covalent attachment to polymer brushes grafted from elastomeric polydimethylsiloxane (PDMS) stamps. The brushes consist of poly{N-[tris(hydroxymethyl)-methyl]acrylamide} (PTrisAAm) synthesized by reversible addition-fragmentation chain-transfer (RAFT)-polymerization and used for immobilization of the alkoxysilane-based ink by substituting the alkoxy moieties with polymer-bound hydroxyl groups. Upon physical contact of the silane-carrying polymers with surfaces, the conjugated silane transfers to the substrate, thus completely suppressing ink-flow and, in turn, maximizing printing accuracy even for otherwise not addressable substrate topographies. We provide a concisely conducted investigation on polymer brush formation using atomic force microscopy (AFM) and ellipsometry as well as ink immobilization utilizing two-dimensional proton nuclear Overhauser enhancement spectroscopy (H-1-H-1-NOESY-NMR). We analyze the mu CP process by printing onto Si-wafers and show how even distinctively rough surfaces can be addressed, which otherwise represent particularly challenging substrates.}, language = {en} } @article{RiemerRiemerKruegeretal.2021, author = {Riemer, Nastja and Riemer, Martin and Kr{\"u}ger, Mandy and Clarkson, Guy J. and Shipman, Michael and Schmidt, Bernd}, title = {Synthesis of arylidene-beta-lactams via exo-selective Matsuda-Heck arylation of methylene-beta-lactams}, series = {The journal of organic chemistry : JOC}, volume = {86}, journal = {The journal of organic chemistry : JOC}, number = {13}, publisher = {American Chemical Society}, address = {Washington}, issn = {0022-3263}, doi = {10.1021/acs.joc.1c00638}, pages = {8786 -- 8796}, year = {2021}, abstract = {exo-Methylene-beta-lactams were synthesized in two steps from commercially available 3-bromo-2-(bromomethyl)-propionic acid and reacted with arene diazonium salts in a Heck-type arylation in the presence of catalytic amounts of Pd(OAc)(2) under ligand-free conditions. The products, arylidene-beta-lactams, were obtained in high yields as single isomers. The beta-hydride elimination step of the Pd-catalyzed coupling reaction proceeds with high exo-regioselectivity and E-stereoselectivity. With aryl iodides, triflates, or bromides, the coupling products were isolated only in low yields, due to extensive decomposition of the starting material at elevated temperatures. This underlines that arene diazonium salts can be superior arylating reagents in Heck-type reactions and yield coupling products in synthetically useful yields and selectivities when conventional conditions fail.}, language = {en} } @article{BalischewskiChoiBehrensetal.2021, author = {Balischewski, Christian and Choi, Hyung-Seok and Behrens, Karsten and Beqiraj, Alkit and K{\"o}rzd{\"o}rfer, Thomas and Gessner, Andre and Wedel, Armin and Taubert, Andreas}, title = {Metal sulfide nanoparticle synthesis with ionic liquids state of the art and future perspectives}, series = {ChemistryOpen}, volume = {10}, journal = {ChemistryOpen}, number = {2}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2191-1363}, doi = {10.1002/open.202000357}, pages = {272 -- 295}, year = {2021}, abstract = {Metal sulfides are among the most promising materials for a wide variety of technologically relevant applications ranging from energy to environment and beyond. Incidentally, ionic liquids (ILs) have been among the top research subjects for the same applications and also for inorganic materials synthesis. As a result, the exploitation of the peculiar properties of ILs for metal sulfide synthesis could provide attractive new avenues for the generation of new, highly specific metal sulfides for numerous applications. This article therefore describes current developments in metal sulfide nano-particle synthesis as exemplified by a number of highlight examples. Moreover, the article demonstrates how ILs have been used in metal sulfide synthesis and discusses the benefits of using ILs over more traditional approaches. Finally, the article demonstrates some technological challenges and how ILs could be used to further advance the production and specific property engineering of metal sulfide nanomaterials, again based on a number of selected examples.}, language = {en} } @article{QuanHaerkXuetal.2021, author = {Quan, Ting and Haerk, Eneli and Xu, Yaolin and Ahmet, Ibbi and H{\"o}hn, Christian and Mei, Shilin and Lu, Yan}, title = {Unveiling the formation of solid electrolyte interphase and its temperature dependence in "Water-in-Salt" supercapacitors}, series = {ACS applied materials \& interfaces}, volume = {13}, journal = {ACS applied materials \& interfaces}, number = {3}, publisher = {American Chemical Society}, address = {Washington}, issn = {1944-8244}, doi = {10.1021/acsami.0c19506}, pages = {3979 -- 3990}, year = {2021}, abstract = {"Water-in-salt" (WIS) electrolytes have emerged as an excellent superconcentrated ionic medium for high-power energy storage systems such as supercapacitors due to their extended working potential compared to the conventional dilute aqueous electrolyte. In this work, we have investigated the performance of WIS supercapacitors using hollow carbon nanoplates as electrodes and compared it to that based on the conventional "salt-in-water" electrolytes. Moreover, the potentiostatic electrochemical impedance spectroscopy has been employed to provide an insightful look into the charge transport properties, which also, for the first time, reveals the formation of a solid-electrolyte interphase (SEI and their temperature-dependent impedance for charge transfer and adsorption. Furthermore, the effect of temperature on the electrochemical performance of the WIS supercapacitors in the temperature range from 15 to 60 degrees C has been studied, which presents a gravimetric capacitance of 128 F g(-1) and a volumetric capacitance of 197.12 F cm(-3) at 55 degrees C compared to 87.5 F g(-1) and 134.75 F cm(-3) at 15 degrees C. The in-depth understanding about the formation of SEI layer and the electrochemical performance at different temperatures for WIS supercapacitors will assist the efforts toward designing better aqueous electrolytes for supercapacitors.}, language = {en} } @article{BehlBalkLuetzowetal.2021, author = {Behl, Marc and Balk, Maria and L{\"u}tzow, Karola and Lendlein, Andreas}, title = {Impact of block sequence on the phase morphology of multiblock copolymers obtained by high-throughput robotic synthesis}, series = {European polymer journal : EPJ}, volume = {143}, journal = {European polymer journal : EPJ}, publisher = {Elsevier}, address = {Oxford}, issn = {0014-3057}, doi = {10.1016/j.eurpolymj.2020.110207}, pages = {9}, year = {2021}, abstract = {The chemical nature, the number length of integrated building blocks, as well as their sequence structure impact the phase morphology of multiblock copolymers (MBC) consisting of two non-miscible block types. We hypothesized that a strictly alternating sequence should favour phase segregation and in this way the elastic properties. A library of well-defined MBCs composed of two different hydrophobic, semi-crystalline blocks providing domains with well-separated melting temperatures (T(m)s) were synthesized from the same type of precursor building blocks as strictly alternating (MBCsalt) or random (MBCsran) MBCs and compared. Three different series of MBCsalt or MBCsran were synthesized by high-throughput synthesis by coupling oligo(e-caprolactone) (OCL) of different molecular weights (2, 4, and 8 kDa) with oligotetrahydrofuran (OTHF, 2.9 kDa) via Steglich esterification in which the molar ratio of the reaction partners was slightly adjusted. Maximum of weight average molecular weight (M-w) were 65,000 g center dot mol(-1), 165,000 g center dot mol(-1), and 168,000 g center dot mol(-1) for MBCsalt and 80,500 g center dot mol(-1), 100,000 g center dot mol(-1), and 147,600 g center dot mol(-1) for MBCsran. When Mw increased, a decrease of both Tms associated to the melting of the OCL and OTHF domains was observed for all MBCs. T-m (OTHF) of MBCsran was always higher than Tm (OTHF) of MBCsalt, which was attributed to a better phase segregation. In addition, the elongation at break of MBCsalt was almost half as high when compared to MBCsran. In this way this study elucidates role of the block length and sequence structure in MBCs and enables a quantitative discussion of the structure-function relationship when two semi-crystalline block segments are utilized for the design of block copolymers.}, language = {en} } @article{SchlappaBrenkerBresseletal.2021, author = {Schlappa, Stephanie and Brenker, Lee Josephine and Bressel, Lena and Hass, Roland and M{\"u}nzberg, Marvin}, title = {Process characterization of polyvinyl acetate emulsions applying inline photon density wave spectroscopy at high solid contents}, series = {Polymers / Molecular Diversity Preservation International}, volume = {13}, journal = {Polymers / Molecular Diversity Preservation International}, number = {4}, publisher = {MDPI}, address = {Basel}, issn = {2073-4360}, doi = {10.3390/polym13040669}, pages = {15}, year = {2021}, abstract = {The high solids semicontinuous emulsion polymerization of polyvinyl acetate using poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated by optical spectroscopy. The suitability of Photon Density Wave (PDW) spectroscopy as inline Process Analytical Technology (PAT) for emulsion polymerization processes at high solid contents (>40\% (w/w)) is studied and evaluated. Inline data on absorption and scattering in the dispersion is obtained in real-time. The radical polymerization of vinyl acetate to polyvinyl acetate using ascorbic acid and sodium persulfate as redox initiator system and poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated. Starved-feed radical emulsion polymerization yielded particle sizes in the nanometer size regime. PDW spectroscopy is used to monitor the progress of polymerization by studying the absorption and scattering properties during the synthesis of dispersions with increasing monomer amount and correspondingly decreasing feed rate of protective colloid. Results are compared to particle sizes determined with offline dynamic light scattering (DLS) and static light scattering (SLS) during the synthesis.}, language = {en} } @article{HarmanliTarakinaAntoniettietal.2021, author = {Harmanli, İpek and Tarakina, Nadezda and Antonietti, Markus and Oschatz, Martin}, title = {"Giant" nitrogen uptake in ionic liquids confined in carbon pores}, series = {Journal of the American Chemical Society}, volume = {143}, journal = {Journal of the American Chemical Society}, number = {25}, publisher = {American Chemical Society}, address = {Washington}, issn = {0002-7863}, doi = {10.1021/jacs.1c00783}, pages = {9377 -- 9384}, year = {2021}, abstract = {Ionic liquids are well known for their high gas absorption capacity. It is shown that this is not a solvent constant, but can be enhanced by another factor of 10 by pore confinement, here of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EmimOAc) in the pores of carbon materials. A matrix of four different carbon compounds with micro- and mesopores as well as with and without nitrogen doping is utilized to investigate the influence of the carbons structure on the nitrogen uptake in the pore-confined EmimOAc. In general, the absorption is most improved for IL in micropores and in nitrogen-doped carbon. This effect is so large that it is already seen in TGA and DSC experiments. Due to the low vapor pressure of the IL, standard volumetric sorption experiments can be used to quantify details of this effect. It is reasoned that it is the change of the molecular arrangement of the ions in the restricted space of the pores that creates additional free volume to host molecular nitrogen.}, language = {en} } @article{FriessLendleinWischke2021, author = {Frieß, Fabian and Lendlein, Andreas and Wischke, Christian}, title = {Switching microobjects from low to high aspect ratios using a shape-memory effect}, series = {Soft matter}, volume = {17}, journal = {Soft matter}, number = {41}, publisher = {Royal Society of Chemistry}, address = {London}, issn = {1744-6848}, doi = {10.1039/d1sm00947h}, pages = {9326 -- 9331}, year = {2021}, abstract = {Spherical particles from shape-memory polymers (SMP) can be stretched to ellipsoids with high aspect ratio (AR) and temporarily stabilized. They can switch back to low AR upon thermal stimulation. Here, the creation of an alternative shape-switching capability of particles from low to high AR is introduced, where a SMP matrix from polyvinyl alcohol (PVA) is used to create crosslinked high AR particles and to program the embedded micrometer-sized particles from a second SMP (oligo(epsilon-caprolactone) micronetworks, MN) with a low switching temperature T-sw. This programming proceeds through shape-recovery of the PVA matrix, from which the MN are harvested by PVA matrix dissolution. The use of a dissolvable SMP matrix may be a general strategy to efficiently create systems with complex moving capabilities.}, language = {en} } @article{LauGossenLendlein2021, author = {Lau, Skadi and Gossen, Manfred and Lendlein, Andreas}, title = {Designing cardiovascular implants taking in view the endothelial basement membrane}, series = {International journal of molecular sciences}, volume = {22}, journal = {International journal of molecular sciences}, number = {23}, publisher = {MDPI}, address = {Basel}, issn = {1422-0067}, doi = {10.3390/ijms222313120}, pages = {26}, year = {2021}, abstract = {Insufficient endothelialization of cardiovascular grafts is a major hurdle in vascular surgery and regenerative medicine, bearing a risk for early graft thrombosis. Neither of the numerous strategies pursued to solve these problems were conclusive. Endothelialization is regulated by the endothelial basement membrane (EBM), a highly specialized part of the vascular extracellular matrix. Thus, a detailed understanding of the structure-function interrelations of the EBM components is fundamental for designing biomimetic materials aiming to mimic EBM functions. In this review, a detailed description of the structure and functions of the EBM are provided, including the luminal and abluminal interactions with adjacent cell types, such as vascular smooth muscle cells. Moreover, in vivo as well as in vitro strategies to build or renew EBM are summarized and critically discussed. The spectrum of methods includes vessel decellularization and implant biofunctionalization strategies as well as tissue engineering-based approaches and bioprinting. Finally, the limitations of these methods are highlighted, and future directions are suggested to help improve future design strategies for EBM-inspired materials in the cardiovascular field.}, language = {en} } @article{KogikoskiJuniorDuttaBald2021, author = {Kogikoski Junior, Sergio and Dutta, Anushree and Bald, Ilko}, title = {Spatial separation of plasmonic hot-electron generation and a hydrodehalogenation reaction center using a DNA wire}, series = {ACS nano}, volume = {15}, journal = {ACS nano}, number = {12}, publisher = {American Chemical Society}, address = {Washington}, issn = {1936-0851}, doi = {10.1021/acsnano.1c09176}, pages = {20562 -- 20573}, year = {2021}, abstract = {Using hot charge carriers far from a plasmonic nanoparticle surface is very attractive for many applications in catalysis and nanomedicine and will lead to a better understanding of plasmon-induced processes, such as hot-charge-carrier- or heat-driven chemical reactions. Herein we show that DNA is able to transfer hot electrons generated by a silver nanoparticle over several nanometers to drive a chemical reaction in a molecule nonadsorbed on the surface. For this we use 8-bromo-adenosine introduced in different positions within a double-stranded DNA oligonucleotide. The DNA is also used to assemble the nanoparticles into nanoparticles ensembles enabling the use of surface-enhanced Raman scattering to track the decomposition reaction. To prove the DNA-mediated transfer, the probe molecule was insulated from the source of charge carriers, which hindered the reaction. The results indicate that DNA can be used to study the transfer of hot electrons and the mechanisms of advanced plasmonic catalysts.}, language = {en} } @article{FudickarBauchIhmelsetal.2021, author = {Fudickar, Werner and Bauch, Marcel and Ihmels, Heiko and Linker, Torsten}, title = {DNA-triggered enhancement of singlet oxygen production by pyridinium alkynylanthracenes}, series = {Chemistry - a European journal}, volume = {27}, journal = {Chemistry - a European journal}, number = {54}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1521-3765}, doi = {10.1002/chem.202101918}, pages = {13591 -- 13604}, year = {2021}, abstract = {There is an ongoing interest in O-1(2) sensitizers, whose activity is selectively controlled by their interaction with DNA. To this end, we synthesized three isomeric pyridinium alkynylanthracenes 2 o-p and a water-soluble trapping reagent for O-1(2). In water and in the absence of DNA, these dyes show a poor efficiency to sensitize the photooxygenation of the trapping reagent as they decompose due to electron transfer processes. In contrast, in the presence of DNA O-1(2) is generated from the excited DNA-bound ligand. The interactions of 2 o-p with DNA were investigated by thermal DNA melting studies, UV/vis and fluorescence spectroscopy, and linear and circular dichroism spectroscopy. Our studies revealed an intercalative binding with an orientation of the long pyridyl-alkynyl axis parallel to the main axis of the DNA base pairs. In the presence of poly(dA : dT), all three isomers show an enhanced formation of singlet oxygen, as indicated by the reaction of the latter with the trapping reagent. With green light irradiation of isomer 2 o in poly(dA : dT), the conversion rate of the trapping reagent is enhanced by a factor >10. The formation of O-1(2) was confirmed by control experiments under anaerobic conditions, in deuterated solvents, or by addition of O-1(2) quenchers. When bound to poly(dG : dC), the opposite effect was observed only for isomers 2 o and 2 m, namely the trapping reagent reacted significantly slower. Overall, we showed that pyridinium alkynylanthracenes are very useful intercalators, that exhibit an enhanced photochemical O-1(2) generation in the DNA-bound state.}, language = {en} } @article{BalkBehlNoecheletal.2021, author = {Balk, Maria and Behl, Marc and N{\"o}chel, Ulrich and Lendlein, Andreas}, title = {Enzymatically triggered Jack-in-the-box-like hydrogels}, series = {ACS applied materials \& interfaces / American Chemical Society}, volume = {13}, journal = {ACS applied materials \& interfaces / American Chemical Society}, number = {7}, publisher = {American Chemical Society}, address = {Washington, DC}, issn = {1944-8244}, doi = {10.1021/acsami.1c00466}, pages = {8095 -- 8101}, year = {2021}, abstract = {Enzymes can support the synthesis or degradation of biomacromolecules in natural processes. Here, we demonstrate that enzymes can induce a macroscopic-directed movement of microstructured hydrogels following a mechanism that we call a "Jack-in-the-box" effect. The material's design is based on the formation of internal stresses induced by a deformation load on an architectured microscale, which are kinetically frozen by the generation of polyester locking domains, similar to a Jack-in-thebox toy (i.e., a compressed spring stabilized by a closed box lid). To induce the controlled macroscopic movement, the locking domains are equipped with enzyme-specific cleavable bonds (i.e., a box with a lock and key system). As a result of enzymatic reaction, a transformed shape is achieved by the release of internal stresses. There is an increase in entropy in combination with a swelling-supported stretching of polymer chains within the microarchitectured hydrogel (i.e., the encased clown pops-up with a pre-stressed movement when the box is unlocked). This utilization of an enzyme as a physiological stimulus may offer new approaches to create interactive and enzyme-specific materials for different applications such as an optical indicator of the enzyme's presence or actuators and sensors in biotechnology and in fermentation processes.}, language = {en} } @article{OloyaNamukobeHeydenreichetal.2021, author = {Oloya, Benson and Namukobe, Jane and Heydenreich, Matthias and Ssengooba, Willy and Schmidt, Bernd and Byamukama, Robert}, title = {Antimycobacterial activity of the extract and isolated compounds from the stem bark of Zanthoxylum leprieurii Guill. and Perr.}, series = {Natural product communications : an international journal for communications and reviews}, volume = {16}, journal = {Natural product communications : an international journal for communications and reviews}, number = {8}, publisher = {Sage Publ.}, address = {Thousand Oaks}, issn = {1934-578X}, doi = {10.1177/1934578X211035851}, pages = {8}, year = {2021}, abstract = {Zanthoxylum leprieurii Guill. and Perr. (Rutaceae) stem bark is used locally in Uganda for treating tuberculosis (TB) and cough-related infections. Lupeol (1), sesamin (2), trans-fagaramide (3), arnottianamide (4), (S)-marmesinin (5), and hesperidin (6) were isolated from the chloroform/methanol (1:1) extract of Z. leprieurii stem bark. Their structures were elucidated using spectroscopic techniques and by comparison with literature data. Furthermore, the extract and isolated compounds were subjected to antimycobacterial activity. The extract exhibited moderate activity against the susceptible (H(37)Rv) TB strain, but weak activity against the multidrug resistant (MDR)-TB strain with minimum inhibitory concentrations (MICs) of 586.0 and 1172.0 mu g/mL, respectively. Compound 3 (trans-fagaramide) showed significant antimycobacterial activity against the susceptible (H(37)Rv) TB strain (MIC 6 mu g/mL), but moderate activity against the MDR-TB strain (MIC 12.2 mu g/mL). Compounds 2, 5, 6, and 1 showed moderate activities against the susceptible (H(37)Rv) strain (MIC 12.2-98.0 mu g/mL) and moderate to weak activities against the MDR-TB strain (MIC 24.4-195.0 mu g/mL). This study reports for the first time the isolation of compounds 1 to 6 from the stem bark of Z leprieurii. trans-Fagaramide (3) may present a vital template in pursuit of novel and highly effective TB drugs.}, language = {en} } @article{FolikumahBehlLendlein2021, author = {Folikumah, Makafui Yao and Behl, Marc and Lendlein, Andreas}, title = {Thiol-Thioester exchange reactions in precursors enable pH-triggered hydrogel formation}, series = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, volume = {22}, journal = {Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences}, number = {5}, publisher = {American Chemical Society}, address = {Washington}, issn = {1525-7797}, doi = {10.1021/acs.biomac.0c01690}, pages = {1875 -- 1884}, year = {2021}, abstract = {Bio-interactive hydrogel formation in situ requires sensory capabilities toward physiologically relevant stimuli. Here, we report on pH-controlled in situ hydrogel formation relying on latent cross-linkers, which transform from pH sensors to reactive molecules. In particular, thiopeptolide/thio-depsipeptides were capable of pH-sensitive thiol-thioester exchange reactions to yield a,co-dithiols, which react with maleimide-functionalized multi-arm polyethylene glycol to polymer networks. Their water solubility and diffusibility qualify thiol/thioester-containing peptide mimetics as sensory precursors to drive in situ localized hydrogel formation with potential applications in tissue regeneration such as treatment of inflamed tissues of the urinary tract.}, language = {en} }