@misc{BrauneLatourReinthaleretal.2019, author = {Braune, Steffen and Latour, Robert A. and Reinthaler, Markus and Landmesser, Ulf and Lendlein, Andreas and Jung, Friedrich}, title = {In Vitro Thrombogenicity Testing of Biomaterials}, series = {Advanced healthcare materials}, volume = {8}, journal = {Advanced healthcare materials}, number = {21}, publisher = {Wiley}, address = {Hoboken}, issn = {2192-2640}, doi = {10.1002/adhm.201900527}, pages = {17}, year = {2019}, abstract = {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.}, language = {en} } @misc{AstFischerMuelleretal.2013, author = {Ast, Sandra and Fischer, Tobias and M{\"u}ller, Holger and Mickler, Wulfhard and Schwichtenberg, Mathias and Rurack, Knut and Holdt, Hans-J{\"u}rgen}, title = {Integration of the 1,2,3-Triazole "Click" Motif as a potent signalling element in metal ion responsive fluorescent probes}, series = {Chemistry - a European journal}, volume = {19}, journal = {Chemistry - a European journal}, number = {9}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0947-6539}, doi = {10.1002/chem.201201575}, pages = {2990 -- 3005}, year = {2013}, abstract = {In a systematic approach we synthesized a new series of fluorescent probes incorporating donoracceptor (D-A) substituted 1,2,3-triazoles as conjugative -linkers between the alkali metal ion receptor N-phenylaza-[18]crown-6 and different fluorophoric groups with different electron-acceptor properties (4-naphthalimide, meso-phenyl-BODIPY and 9-anthracene) and investigated their performance in organic and aqueous environments (physiological conditions). In the charge-transfer (CT) type probes 1, 2 and 7, the fluorescence is almost completely quenched by intramolecular CT (ICT) processes involving charge-separated states. In the presence of Na+ and K+ ICT is interrupted, which resulted in a lighting-up of the fluorescence in acetonitrile. Among the investigated fluoroionophores, compound 7, which contains a 9-anthracenyl moiety as the electron-accepting fluorophore, is the only probe which retains light-up features in water and works as a highly K+/Na+-selective probe under simulated physiological conditions. Virtually decoupled BODIPY-based 6 and photoinduced electron transfer (PET) type probes 35, where the 10-substituted anthracen-9-yl fluorophores are connected to the 1,2,3-triazole through a methylene spacer, show strong ion-induced fluorescence enhancement in acetonitrile, but not under physiological conditions. Electrochemical studies and theoretical calculations were used to assess and support the underlying mechanisms for the new ICT and PET 1,2,3-triazole fluoroionophores.}, language = {en} } @misc{HuZhaoZhangetal.2017, author = {Hu, Shuangyan and Zhao, Junpeng and Zhang, Guangzhao and Schlaad, Helmut}, title = {Macromolecular architectures through organocatalysis}, series = {Progress in Polymer Science}, volume = {74}, journal = {Progress in Polymer Science}, publisher = {Elsevier}, address = {Oxford}, issn = {0079-6700}, doi = {10.1016/j.progpolymsci.2017.07.002}, pages = {34 -- 77}, year = {2017}, abstract = {In virtue of the rising demand for metal-free polymeric materials, organocatalytic polymerization has emerged and blossomed unprecedentedly in the past 15 years into an appealing research area and a powerful arsenal for polymer synthesis. In addition to the inherent merits as being metal-free, small molecule organocatalysts have also provided opportunities to develop alternative and, in many cases, more expedient synthetic approaches toward macromolecular architectures, that play a crucial role in shaping the properties of the obtained polymers. A majority of preliminary studies exploring for new catalysts, catalytic mechanisms and optimized polymerization conditions are extended to application of the catalytic systems on rational design and controlled synthesis of various macromolecular architectures. Such endeavors are described in this review, categorized by the architectural elements including chain structure (types, sequence and composition of monomeric units constituting the polymer chains), topological structure (the fashion different polymer chains are covalently attached to each other within the macromolecule) and functionality (position and amount of functional groups that endow the entire macromolecule with specific chemical, physico-chemical or biological properties). (C) 2017 Published by Elsevier B.V.}, language = {en} } @misc{BaldKeller2014, author = {Bald, Ilko and Keller, Adrian}, title = {Molecular processes studied at a single-molecule level using DNA origami nanostructures and atomic force microscopy}, series = {Molecules}, volume = {19}, journal = {Molecules}, number = {9}, publisher = {MDPI}, address = {Basel}, issn = {1420-3049}, doi = {10.3390/molecules190913803}, pages = {13803 -- 13823}, year = {2014}, abstract = {DNA origami nanostructures allow for the arrangement of different functionalities such as proteins, specific DNA structures, nanoparticles, and various chemical modifications with unprecedented precision. The arranged functional entities can be visualized by atomic force microscopy (AFM) which enables the study of molecular processes at a single-molecular level. Examples comprise the investigation of chemical reactions, electron-induced bond breaking, enzymatic binding and cleavage events, and conformational transitions in DNA. In this paper, we provide an overview of the advances achieved in the field of single-molecule investigations by applying atomic force microscopy to functionalized DNA origami substrates.}, language = {en} } @misc{BleekTaubert2013, author = {Bleek, Katrin and Taubert, Andreas}, title = {New developments in polymer-controlled, bioinspired calcium phosphate mineralization from aqueous solution}, series = {Acta biomaterialia}, volume = {9}, journal = {Acta biomaterialia}, number = {5}, publisher = {Elsevier}, address = {Oxford}, issn = {1742-7061}, doi = {10.1016/j.actbio.2012.12.027}, pages = {6283 -- 6321}, year = {2013}, abstract = {The polymer-controlled and bioinspired precipitation of inorganic minerals from aqueous solution at near-ambient or physiological conditions avoiding high temperatures or organic solvents is a key research area in materials science. Polymer-controlled mineralization has been studied as a model for biomineralization and for the synthesis of (bioinspired and biocompatible) hybrid materials for a virtually unlimited number of applications. Calcium phosphate mineralization is of particular interest for bone and dental repair. Numerous studies have therefore addressed the mineralization of calcium phosphate using a wide variety of low- and high-molecular-weight additives. In spite of the growing interest and increasing number of experimental and theoretical data, the mechanisms of polymer-controlled calcium phosphate mineralization are not entirely clear to date, although the field has made significant progress in the last years. A set of elegant experiments and calculations has shed light on some details of mineral formation, but it is currently not possible to preprogram a mineralization reaction to yield a desired product for a specific application. The current article therefore summarizes and discusses the influence of (macro)molecular entities such as polymers, peptides, proteins and gels on biomimetic calcium phosphate mineralization from aqueous solution. It focuses on strategies to tune the kinetics, morphologies, final dimensions and crystal phases of calcium phosphate, as well as on mechanistic considerations.}, language = {en} } @misc{WolffCaprioglioStolterfohtetal.2019, author = {Wolff, Christian Michael and Caprioglio, Pietro and Stolterfoht, Martin and Neher, Dieter}, title = {Nonradiative Recombination in Perovskite Solar Cells}, series = {Advanced materials}, volume = {31}, journal = {Advanced materials}, number = {52}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0935-9648}, doi = {10.1002/adma.201902762}, pages = {20}, year = {2019}, abstract = {Perovskite solar cells combine high carrier mobilities with long carrier lifetimes and high radiative efficiencies. Despite this, full devices suffer from significant nonradiative recombination losses, limiting their V-OC to values well below the Shockley-Queisser limit. Here, recent advances in understanding nonradiative recombination in perovskite solar cells from picoseconds to steady state are presented, with an emphasis on the interfaces between the perovskite absorber and the charge transport layers. Quantification of the quasi-Fermi level splitting in perovskite films with and without attached transport layers allows to identify the origin of nonradiative recombination, and to explain the V-OC of operational devices. These measurements prove that in state-of-the-art solar cells, nonradiative recombination at the interfaces between the perovskite and the transport layers is more important than processes in the bulk or at grain boundaries. Optical pump-probe techniques give complementary access to the interfacial recombination pathways and provide quantitative information on transfer rates and recombination velocities. Promising optimization strategies are also highlighted, in particular in view of the role of energy level alignment and the importance of surface passivation. Recent record perovskite solar cells with low nonradiative losses are presented where interfacial recombination is effectively overcome-paving the way to the thermodynamic efficiency limit.}, language = {en} } @misc{AstSchmaelzlinLoehmannsroebenetal.2012, author = {Ast, Cindy and Schm{\"a}lzlin, Elmar and L{\"o}hmannsr{\"o}ben, Hans-Gerd and van Dongen, Joost T.}, title = {Optical oxygen micro- and nanosensors for plant applications}, series = {Sensors}, volume = {12}, journal = {Sensors}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s120607015}, pages = {7015 -- 7032}, year = {2012}, abstract = {Pioneered by Clark's microelectrode more than half a century ago, there has been substantial interest in developing new, miniaturized optical methods to detect molecular oxygen inside cells. While extensively used for animal tissue measurements, applications of intracellular optical oxygen biosensors are still scarce in plant science. A critical aspect is the strong autofluorescence of the green plant tissue that interferes with optical signals of commonly used oxygen probes. A recently developed dual-frequency phase modulation technique can overcome this limitation, offering new perspectives for plant research. This review gives an overview on the latest optical sensing techniques and methods based on phosphorescence quenching in diverse tissues and discusses the potential pitfalls for applications in plants. The most promising oxygen sensitive probes are reviewed plus different oxygen sensing structures ranging from micro-optodes to soluble nanoparticles. Moreover, the applicability of using heterologously expressed oxygen binding proteins and fluorescent proteins to determine changes in the cellular oxygen concentration are discussed as potential non-invasive cellular oxygen reporters.}, language = {en} } @misc{KoerzdoerferBredas2014, author = {K{\"o}rzd{\"o}rfer, Thomas and Bredas, Jean-Luc}, title = {Organic electronic materials: recent advances in the DFT description of the ground and excited states using tuned range-separated hybrid functionals}, series = {Accounts of chemical research}, volume = {47}, journal = {Accounts of chemical research}, number = {11}, publisher = {American Chemical Society}, address = {Washington}, issn = {0001-4842}, doi = {10.1021/ar500021t}, pages = {3284 -- 3291}, year = {2014}, abstract = {CONSPECTUS: Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers. In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter. We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of pi-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the reliable prediction of the optical absorption spectrum of low-band-gap polymers. We also explain why the use of standard, out-of-the-box range-separation parameters is not recommended for the DFT and/or TD-DFT description of the ground and excited states of extended, pi-conjugated systems. Finally, we highlight a severe drawback of tuned range-separated hybrid functionals by discussing the example of the calculation of bond-length alternation in polyacetylene, which leads us to point out the challenges for future developments in this field.}, language = {en} } @misc{GangloffUlbrichtLorsonetal.2016, author = {Gangloff, Niklas and Ulbricht, Juliane and Lorson, Thomas and Schlaad, Helmut and Luxenhofer, Robert}, title = {Peptoids and Polypeptoids at the Frontier of Supra- and Macromolecular Engineering}, series = {Chemical reviews}, volume = {116}, journal = {Chemical reviews}, publisher = {American Chemical Society}, address = {Washington}, issn = {0009-2665}, doi = {10.1021/acs.chemrev.5b00201}, pages = {1753 -- 1802}, year = {2016}, language = {en} } @misc{KosmellaKoetz2012, author = {Kosmella, Sabine and Koetz, Joachim}, title = {Polymer-modified w/o microemulsions - with tunable droplet-droplet interactions}, series = {Current opinion in colloid \& interface science : current chemistry}, volume = {17}, journal = {Current opinion in colloid \& interface science : current chemistry}, number = {5}, publisher = {Elsevier}, address = {London}, issn = {1359-0294}, doi = {10.1016/j.cocis.2012.06.004}, pages = {261 -- 265}, year = {2012}, abstract = {Water soluble polymers can be incorporated into reverse microemulsion droplets without leaving the isotropic phase region. When the polymer is attached to the surfactant film the bending elasticity is changed, and droplet-droplet interactions are influenced. Different methods are available for studying the droplet-droplet interactions in more detail, e.g. SANS. SAXS and DLS. Conductometric measurements are very useful for detecting exchange processes between the droplets. In presence of polyampholytes a pH dependent tuning of the membrane properties becomes possible, experimentally detectable by conductometry.}, language = {en} }