TY - JOUR A1 - Choi, Youngeun A1 - Kotthoff, Lisa A1 - Olejko, Lydia A1 - Resch-Genger, Ute A1 - Bald, Ilko T1 - DNA origami-based forster resonance energy-transfer Nanoarrays and their application as ratiometric sensors JF - ACS applied materials & interfaces N2 - DNA origami nanostructures provide a platform where dye molecules can be arranged with nanoscale accuracy allowing to assemble multiple fluorophores without dye-dye aggregation. Aiming to develop a bright and sensitive ratiometric sensor system, we systematically studied the optical properties of nanoarrays of dyes built on DNA origami platforms using a DNA template that provides a high versatility of label choice at minimum cost. The dyes are arranged at distances, at which they efficiently interact by Forster resonance energy transfer (FRET). To optimize array brightness, the FRET efficiencies between the donor fluorescein (FAM) and the acceptor cyanine 3 were determined for different sizes of the array and for different arrangements of the dye molecules within the array. By utilizing nanoarrays providing optimum FRET efficiency and brightness, we subsequently designed a ratiometric pH nanosensor using coumarin 343 as a pH-inert FRET donor and FAM as a pH responsive acceptor. Our results indicate that the sensitivity of a ratiometric sensor can be improved simply by arranging the dyes into a well-defined array. The dyes used here can be easily replaced by other analyte-responsive dyes, demonstrating the huge potential of DNA nanotechnology for light harvesting, signal enhancement, and sensing schemes in life sciences. KW - DNA origami KW - nanoarray KW - FRET KW - ratiometric sensing KW - pH sensing Y1 - 2018 U6 - https://doi.org/10.1021/acsami.8b03585 SN - 1944-8244 SN - 1944-8252 VL - 10 IS - 27 SP - 23295 EP - 23302 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Goulet-Hanssens, Alexis A1 - Rietze, Clemens A1 - Titov, Evgenii A1 - Abdullahu, Leonora A1 - Grubert, Lutz A1 - Saalfrank, Peter A1 - Hecht, Stefan T1 - Hole Catalysis as a General Mechanism for Efficient and Wavelength-Independent Z -> E Azobenzene Isomerization JF - CHEM N2 - Whereas the reversible reduction of azobenzenes has been known for decades, their oxidation is destructive and as a result has been notoriously overlooked. Here, we show that a chain reaction leading to quantitative Z -> E isomerization can be initiated before reaching the destructive anodic peak potential. This hole-catalyzed pathway is accessible to all azobenzenes, without exception, and offers tremendous advantages over the recently reported reductive, radical-anionic pathway because it allows for convenient chemical initiation without the need for electrochemical setups and in the presence of air. In addition, catalytic amounts of metal-free sensitizers, such as methylene blue, can be used as excited-state electron acceptors, enabling a shift of the excitation wavelength to the far red of the azobenzene absorption (up to 660 nm) and providing quantum yields exceeding unity (up to 200%). Our approach will boost the efficiency and sensitivity of optically dense liquid-crystalline and solid photo-switchable materials. Y1 - 2018 U6 - https://doi.org/10.1016/j.chempr.2018.06.002 SN - 2451-9294 VL - 4 IS - 7 SP - 1740 EP - 1755 PB - Cell Press CY - Cambridge ER - TY - JOUR A1 - Heiden, Sophia A1 - Wirth, Jonas A1 - Campen, Richard Kramer A1 - Saalfrank, Peter T1 - Water molecular beam scattering at alpha-Al2O3(0001) BT - an ab initio molecular dynamics study JF - The journal of physical chemistry : C, Nanomaterials and interfaces N2 - Recent molecular beam experiments have shown that water may adsorb molecularly or dissociatively on an α-Al2O3(0001) surface, with enhanced dissociation probability compared to “pinhole dosing”, i.e., adsorption under thermal equilibrium conditions. However, precise information on the ongoing reactions and their relative probabilities is missing. In order to shed light on molecular beam scattering for this system, we perform ab initio molecular dynamics calculations to simulate water colliding with α-Al2O3(0001). We find that single water molecules hitting a cold, clean surface from the gas phase are either reflected, molecularly adsorbed, or dissociated (so-called 1–2 dissociation only). A certain minimum translational energy (above 0.1 eV) seems to be required to enforce dissociation, which may explain the higher dissociation probability in molecular beam experiments. When the surface is heated and/or when refined surface and beam models are applied (preadsorption with water or water fragments, clustering and internal preexcitation in the beam), additional channels open, among them physisorption, water clustering on the surface, and so-called 1–4 and 1–4′ dissociation. Y1 - 2018 U6 - https://doi.org/10.1021/acs.jpcc.8b04179 SN - 1932-7447 VL - 122 IS - 27 SP - 15494 EP - 15504 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Schwarze, Thomas A1 - Riemer, Janine A1 - Holdt, Hans-Jürgen T1 - A Ratiometric Fluorescent Probe for K+ in Water Based on a Phenylaza-18-Crown-6 Lariat Ether JF - Chemistry - a European journal N2 - This work presents two molecular fluorescent probes 1 and 2 for the selective determination of physiologically relevant K+ levels in water based on a highly K+/Na+ selective building block, the o-(2-methoxyethoxy)phenylaza-18-crown-6 lariat ether unit. Fluorescent probe 1 showed a high K+-induced fluorescence enhancement (FE) by a factor of 7.7 of the anthracenic emission and a dissociation constant (K-d) value of 38mm in water. Further, for 2+K+, we observed a dual emission behavior at 405 and 505nm. K+ increases the fluorescence intensity of 2 at 405nm by a factor of approximately 4.6 and K+ decreases the fluorescence intensity at 505nm by a factor of about 4.8. Fluorescent probe 2+K+ exhibited a K-d value of approximately 8mm in Na+-free solutions and in combined K+/Na+ solution a similar K-d value of about 9mm was found, reflecting the high K+/Na+ selectivity of 2 in water. Therefore, 2 is a promising fluorescent tool to measure ratiometrically and selectively physiologically relevant K+ levels. KW - charge transfer KW - crown compounds KW - fluorescence KW - potassium KW - ratiometric sensors Y1 - 2018 U6 - https://doi.org/10.1002/chem.201802306 SN - 0947-6539 SN - 1521-3765 VL - 24 IS - 40 SP - 10116 EP - 10121 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schürmann, Robin Mathis A1 - Vogel, Stefanie A1 - Ebel, Kenny A1 - Bald, Ilko T1 - The physico-chemical basis of DNA radiosensitization BT - implications for cancer radiation therapy JF - Chemistry - a European journal N2 - High-energy radiation is used in combination with radiosensitizing therapeutics to treat cancer. The most common radiosensitizers are halogenated nucleosides and cisplatin derivatives, and recently also metal nanoparticles have been suggested as potential radiosensitizing agents. The radiosensitizing action of these compounds can at least partly be ascribed to an enhanced reactivity towards secondary low-energy electrons generated along the radiation track of the high-energy primary radiation, or to an additional emission of secondary reactive electrons close to the tumor tissue. This is referred to as physico-chemical radiosensitization. In this Concept article we present current experimental methods used to study fundamental processes of physico-chemical radiosensitization and discuss the most relevant classes of radiosensitizers. Open questions in the current discussions are identified and future directions outlined, which can lead to optimized treatment protocols or even novel therapeutic concepts. KW - cancer KW - dissociative electron attachment KW - low-energy electrons KW - radiation therapy KW - radiosensitizers Y1 - 2018 U6 - https://doi.org/10.1002/chem.201800804 SN - 0947-6539 SN - 1521-3765 VL - 24 IS - 41 SP - 10271 EP - 10279 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Jia, He A1 - Gao, Haitao A1 - Mei, Shilin A1 - Kneer, Janosch A1 - Lin, Xianzhong A1 - Ran, Qidi A1 - Wang, Fuxian A1 - Palzer, Stefan A1 - Lu, Yan T1 - Cu2O@PNIPAM core-shell microgels as novel inkjet materials for the preparation of CuO hollow porous nanocubes gas sensing layers JF - Journal of materials chemistry : C, Materials for optical and electronic devices N2 - There has been long-standing interest in developing metal oxide-based sensors with high sensitivity, selectivity, fast response and low material consumption. Here we report for the first time the utilization of Cu2O@PNIPAM core-shell microgels with a nanocube-shaped core structure for construction of novel CuO gas sensing layers. The hybrid microgels show significant improvement in colloidal stability as compared to native Cu2O nanocubes. Consequently, a homogeneous thin film of Cu2O@PNIPAM nanoparticles can be engineered in a quite low solid content (1.5 wt%) by inkjet printing of the dispersion at an optimized viscosity and surface tension. Most importantly, thermal treatment of the Cu2O@PNIPAM microgels forms porous CuO nanocubes, which show much faster response to relevant trace NO2 gases than sensors produced from bare Cu2O nanocubes. This outcome is due to the fact that the PNIPAM shell can successfully hinder the aggregation of CuO nanoparticles during pyrolysis, which enables full utilization of the sensor layers and better access of the gas to active sites. These results point out great potential of such an innovative system as gas sensors with low cost, fast response and high sensitivity. Y1 - 2018 U6 - https://doi.org/10.1039/c8tc01995a SN - 2050-7526 SN - 2050-7534 VL - 6 IS - 27 SP - 7249 EP - 7256 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Poghosyan, Armen H. A1 - Shahinyan, A. A. A1 - Koetz, Joachim T1 - Catanionic AOT/BDAC micelles on gold {111} surfaces JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - A sodium dioctyl sulfosuccinate (AOT)/benzyl hexadecyl dimethyl ammonium chloride (BDAC) mixed micelle self-organization and adsorption on gold Au(111) surfaces have been investigated using a molecular dynamics approach. The spherical AOT/BDAC mixed micelle is strongly adsorbed on the gold surface and is disoriented to a cylinder-like shape. KW - AOT/BDAC micelles KW - Gold surfaces KW - Molecular dynamics Y1 - 2018 U6 - https://doi.org/10.1007/s00396-018-4348-1 SN - 0303-402X SN - 1435-1536 VL - 296 IS - 8 SP - 1301 EP - 1306 PB - Springer CY - New York ER - TY - JOUR A1 - Stanglmair, Christoph A1 - Neubrech, Frank A1 - Pacholski, Claudia T1 - Chemical routes to surface enhanced infrared absorption (SEIRA) substrates JF - Zeitschrift für physikalische Chemie : international journal of research in physical chemistry and chemical physics N2 - Bottom-up strategies for fabricating SEIRA substrates are presented. For this purpose, wet-chemically prepared gold nanoparticles are coated with a polystyrene shell and subsequently self-assembled into different nanostructures such as quasi-hexagonally ordered gold nanoparticle monolayers, double layers, and honeycomb structures. Furthermore elongated gold nanostructures are obtained by sintering of gold nanoparticle double layers. The optical properties of these different gold nanostructures are directly connected to their morphology and geometrical arrangement - leading to surface plasmon resonances from the visible to the infrared wavelength range. Finally, SEIRA enhancement factors are determined. Gold nanoparticle double layers show the best performance as SEIRA substrates. KW - bottom-up KW - gold nanoparticles KW - self-assembly KW - surface enhanced spectroscopy Y1 - 2018 U6 - https://doi.org/10.1515/zpch-2018-1132 SN - 0942-9352 VL - 232 IS - 9-11 SP - 1527 EP - 1539 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Rühlmann, Madlen A1 - Büchele, Dominique A1 - Ostermann, Markus A1 - Bald, Ilko A1 - Schmid, Thomas T1 - Challenges in the quantification of nutrients in soils using laser-induced breakdown spectroscopy BT - a case study with calcium JF - Spectrochimica Acta Part B: Atomic Spectroscopy N2 - The quantification of the elemental content in soils with laser-induced breakdown spectroscopy (LIBS) is challenging because of matrix effects strongly influencing the plasma formation and LIBS signal. Furthermore, soil heterogeneity at the micrometre scale can affect the accuracy of analytical results. In this paper, the impact of univariate and multivariate data evaluation approaches on the quantification of nutrients in soil is discussed. Exemplarily, results for calcium are shown, which reflect trends also observed for other elements like magnesium, silicon and iron. For the calibration models, 16 certified reference soils were used. With univariate and multivariate approaches, the calcium mass fractions in 60 soils from different testing grounds in Germany were calculated. The latter approach consisted of a principal component analysis (PCA) of adequately pre-treated data for classification and identification of outliers, followed by partial least squares regression (PLSR) for quantification. For validation, the soils were also characterised with inductively coupled plasma optical emission spectroscopy (ICP OES) and X-ray fluorescence (XRF) analysis. Deviations between the LIBS quantification results and the reference analytical results are discussed. KW - Laser-induced breakdown spectroscopy (LIBS) KW - Soil KW - Multivariate data analysis KW - Principal component analysis (PCA) KW - Partial least squares regression (PLSR) Y1 - 2018 U6 - https://doi.org/10.1016/j.sab.2018.05.003 SN - 0584-8547 VL - 146 SP - 115 EP - 121 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Karras, Manfred A1 - Dabrowski, Michal A1 - Pohl, Radek A1 - Rybacek, Jiri A1 - Vacek, Jaroslav A1 - Bednarova, Lucie A1 - Grela, Karol A1 - Stary, Ivo A1 - Stara, Irena G. A1 - Schmidt, Bernd T1 - Helicenes as Chirality-Inducing Groups in Transition-Metal Catalysis BT - the first helically chiral Olefin Metathesis Catalyst JF - Chemistry - a European journal N2 - Helical chirality is a novel enantioselectivity-inducing property in transition-metal-catalyzed transformations. The principle is illustrated herein for the example of asymmetric olefin metathesis. This work reports the synthesis of the first helically chiral Ru-NHC alkylidene complex from an aminohelicene-derived imidazolium salt, which was ligated to the first generation Hoveyda-Grubbs catalyst. Kinetic data were acquired for benchmark test reactions and compared to an achiral catalyst. The helically chiral Ru-catalyst was evaluated in asymmetric ring-closing metathesis (RCM) and ring-opening metathesis-cross-metathesis (ROM/CM) reactions, which proceeded with promising levels of enantioselectivity. Extensive NMR-spectroscopic investigations and a DFT geometry optimization were performed. These results led to a topographic steric map and calculation of percent-buried-volume values for each quadrant around the metal center. KW - asymmetric catalysis KW - carbene ligands KW - helicenes KW - metathesis KW - ruthenium Y1 - 2018 U6 - https://doi.org/10.1002/chem.201802786 SN - 0947-6539 SN - 1521-3765 VL - 24 IS - 43 SP - 10994 EP - 10998 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Holland-Moritz, Henry A1 - Graupner, Julia A1 - Möller, Wolfhard A1 - Pacholski, Claudia A1 - Ronning, Carsten T1 - Dynamics of nanoparticle morphology under low energy ion irradiation JF - Nanotechnology N2 - If nanostructures are irradiated with energetic ions, the mechanism of sputtering becomes important when the ion range matches about the size of the nanoparticle. Gold nanoparticles with diameters of similar to 50 nm on top of silicon substrates with a native oxide layer were irradiated by gallium ions with energies ranging from 1 to 30 keV in a focused ion beam system. High resolution in situ scanning electron microscopy imaging permits detailed insights in the dynamics of the morphology change and sputter yield. Compared to bulk-like structures or thin films, a pronounced shaping and enhanced sputtering in the nanostructures occurs, which enables a specific shaping of these structures using ion beams. This effect depends on the ratio of nanoparticle size and ion energy. In the investigated energy regime, the sputter yield increases at increasing ion energy and shows a distinct dependence on the nanoparticle size. The experimental findings are directly compared to Monte Carlo simulations obtained from iradina and TRI3DYN, where the latter takes into account dynamic morphological and compositional changes of the target. KW - ion beam KW - nanoparticles KW - sputtering KW - Monte Carlo KW - in situ Y1 - 2018 U6 - https://doi.org/10.1088/1361-6528/aac36c SN - 0957-4484 SN - 1361-6528 VL - 29 IS - 31 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Mertens, Monique A1 - Hilsch, Malte A1 - Haralampiev, Ivan A1 - Volkmer, Rudolf A1 - Wessig, Pablo A1 - Müller, Peter T1 - Synthesis and characterization of a new Bifunctionalized, Fluorescent, and Amphiphilic molecule for recruiting SH-Containing molecules to membranes JF - ChemBioChem N2 - This study describes the synthesis and characterization of an amphiphilic construct intended to recruit SH-containing molecules to membranes. The construct consists of 1)an aliphatic chain to enable anchoring within membranes, 2)a maleimide moiety to react with the sulfhydryl group of a soluble (bio)molecule, and 3)a fluorescence moiety to allow the construct to be followed by fluorescence spectroscopy and microscopy. It is shown that the construct can be incorporated into preformed membranes, thus allowing application of the approach with biological membranes. The close proximity between the fluorophore and the maleimide moiety within the construct causes fluorescence quenching. This allows monitoring of the reaction with SH-containing molecules by measurement of increases in fluorescence intensity and lifetime. Notably, the construct distributes into laterally ordered membrane domains of lipid vesicles, which is probably triggered by the length of its membrane anchor. The advantages of the new construct can be employed for several biological, biotechnological, and medicinal applications. KW - DBD dyes KW - fatty acids KW - liposomes KW - maleimide KW - membranes KW - palmitoylation Y1 - 2018 U6 - https://doi.org/10.1002/cbic.201800268 SN - 1439-4227 SN - 1439-7633 VL - 19 IS - 15 SP - 1643 EP - 1647 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Shainyan, Bagrat A. A1 - Suslova, Elena N. A1 - Tran Dinh Phien, A1 - Shlykov, Sergey A. A1 - Kleinpeter, Erich T1 - Synthesis, conformational preferences in gas and solution, and molecular gear rotation in 1-(dimethylamino)-1-phenyl-1-silacyclohexane by gas phase electron diffraction (GED), LT NMR and theoretical calculations JF - Tetrahedron N2 - 1-(Dimethylamino)-1-phenyl-1-silacyclohexane 1, was synthesized, and its molecular structure and conformational properties studied by gas-phase electron diffraction (GED), low temperature C-13 NMR spectroscopy and quantum-chemical calculations. The predominance of the 1-Ph-ax conformer (1-Ph-eq:1-Ph-ax ratio of 20:80%, Delta G degrees (317 K) = -0.87 kcal/mol) in the gas phase is close to the theoretically estimated conformational equilibrium. In solution, low temperature NMR spectroscopy showed analyzable decoalescence of C-ipso and C(1,5) carbon signals in C-13 NMR spectra at 103 K. Opposite to the gas state in the freon solution employed (CD2Cl2/CHFCl2/CHFCl2 = 1:1:3), which is still liquid at 100 K, the 1-Ph-eq conformer was found to be the preferred one [(1-Ph-eq: 1-Ph-ax = 77%: 23%, K = 77/23 = 2.8; -Delta G degrees = -RT In K (at 103 K) = 0.44 +/- 0.1 kcal/mol]. When comparing 1 with 1-phenyl-1-(X)silacylohexanes (X = H, Me, OMe, F, Cl), studied so far, the trend of predominance of the Ph-ax conformer in the gas phase and of the Ph-eq conformer in solution is confirmed. KW - 1-(Dimethylamino)-1-phenyl-1-silacyclohexane KW - Conformational analysis KW - Gas phase electron diffraction KW - Low-temperature d-NMR KW - DFT KW - MP2 KW - M062X/6-311G** calculations Y1 - 2018 U6 - https://doi.org/10.1016/j.tet.2018.06.023 SN - 0040-4020 VL - 74 IS - 32 SP - 4299 EP - 4307 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Kretzschmar, Jerome A1 - Haubitz, Toni A1 - Huebner, Rene A1 - Weiss, Stephan A1 - Husar, Richard A1 - Brendler, Vinzenz A1 - Stumpf, Thorsten T1 - Network-like arrangement of mixed-valence uranium oxide nanoparticles after glutathione-induced reduction of uranium(VI) JF - Chemical communications N2 - Glutathione (GSH), a ubiquitous intracellular reducing tripeptide, is able to reduce hexavalent uranium, U(VI), to its tetravalent form, U(IV), in aqueous media in vitro, inducing the formation of nanocrystalline mixed-valence uranium oxide particles. After the initial reduction to U(V) and subsequent dismutation, the yielded U(IV) rapidly hydrolyses under near-neutral conditions forming 2-5 nm sized nanoparticles. The latter further aggregate to 20-40 nm chain-like building blocks that finally arrange as network-like structures. Y1 - 2018 U6 - https://doi.org/10.1039/c8cc02070a SN - 1359-7345 SN - 1364-548X VL - 54 IS - 63 SP - 8697 EP - 8700 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Klopsch, Rebecca A1 - Baldermann, Susanne A1 - Voss, Alexander A1 - Rohn, Sascha A1 - Schreiner, Monika A1 - Neugart, Susanne T1 - Bread enriched with legume microgreens and leaves BT - ontogenetic and baking-driven changes in the profile of secondary plant metabolites JF - Frontiers in chemistry N2 - Flavonoids, carotenoids, and chlorophylls were characterized in microgreens and leaves of pea (Pisum sativum) and lupin (Lupinus angustifolius) as these metabolites change during ontogeny. All metabolites were higher in the leaves for both species. Acylated quercetin and kaempferol sophorotrioses were predominant in pea. Genistein and malonylated chrysoeriol were predominant in lupin. Further, the impact of breadmaking on these metabolites using pea and lupin material of two ontogenetic stages as an added ingredient in wheat-based bread was assessed. In "pea microgreen bread" no decrease of quercetin was found with regard to the non-processed plant material. However kaempferol glycosides showed slight decreases induced by the breadmaking process in "pea microgreen bread" and "pea leaf bread." In "lupin microgreen bread" no decrease of genistein compared to the non-processed plant material was found. Chrysoeriol glycosides showed slight decreases induced by the breadmaking process in "lupin microgreen bread" and "lupin leaf bread." In all breads, carotenoids and chlorophylls were depleted however pheophytin formation was caused. Thus, pea and lupin microgreens and leaves are suitable, natural ingredients for enhancing health-promoting secondary plant metabolites in bread and may even be used to tailor bread for specific consumer health needs. KW - ontogeny KW - microgreen KW - pea KW - lupin KW - flavonoid KW - carotenoid KW - thermal processing of food Y1 - 2018 U6 - https://doi.org/10.3389/fchem.2018.00322 SN - 2296-2646 VL - 6 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Fang, Liang A1 - Gould, Oliver E. C. A1 - Lysyakova, Liudmila A1 - Jiang, Yi A1 - Sauter, Tilman A1 - Frank, Oliver A1 - Becker, Tino A1 - Schossig, Michael A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Implementing and quantifying the shape-memory effect of single polymeric micro/nanowires with an atomic force microscope JF - ChemPhysChem : a European journal of chemical physics and physical chemistry N2 - The implementation of shape-memory effects (SME) in polymeric micro- or nano-objects currently relies on the application of indirect macroscopic manipulation techniques, for example, stretchable molds or phantoms, to ensembles of small objects. Here, we introduce a method capable of the controlled manipulation and SME quantification of individual micro- and nano-objects in analogy to macroscopic thermomechanical test procedures. An atomic force microscope was utilized to address individual electro-spun poly(ether urethane) (PEU) micro- or nanowires freely suspended between two micropillars on a micro-structured silicon substrate. In this way, programming strains of 10 +/- 1% or 21 +/- 1% were realized, which could be successfully fixed. An almost complete restoration of the original free-suspended shape during heating confirmed the excellent shape-memory performance of the PEU wires. Apparent recovery stresses of sigma(max,app)=1.2 +/- 0.1 and 33.3 +/- 0.1MPa were obtained for a single microwire and nanowire, respectively. The universal AFM test platform described here enables the implementation and quantification of a thermomechanically induced function for individual polymeric micro- and nanosystems. KW - cyclic thermomechanical testing KW - atomic force microscopy KW - soft matter micro- and nanowires KW - shape-memory effect KW - materials science Y1 - 2018 U6 - https://doi.org/10.1002/cphc.201701362 SN - 1439-4235 SN - 1439-7641 VL - 19 IS - 16 SP - 2078 EP - 2084 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zhong, Qi A1 - Mi, Lei A1 - Metwalli, Ezzeldin A1 - Biessmann, Lorenz A1 - Philipp, Martine A1 - Miasnikova, Anna A1 - Laschewsky, Andre A1 - Papadakis, Christine M. A1 - Cubitt, Robert A1 - Schwartzkopf, Matthias A1 - Roth, Stephan V. A1 - Wang, Jiping A1 - Müller-Buschbaum, Peter T1 - Effect of chain architecture on the swelling and thermal response of star-shaped thermo-responsive (poly(methoxy diethylene glycol acrylate)-block-polystyrene)(3) block copolymer films JF - Soft matter N2 - The effect of chain architecture on the swelling and thermal response of thin films obtained from an amphiphilic three-arm star-shaped thermo-responsive block copolymer poly(methoxy diethylene glycol acrylate)-block-polystyrene ((PMDEGA-b-PS)(3)) is investigated by in situ neutron reflectivity (NR) measurements. The PMDEGA and PS blocks are micro-phase separated with randomly distributed PS nanodomains. The (PMDEGA-b-PS)(3) films show a transition temperature (TT) at 33 degrees C in white light interferometry. The swelling capability of the (PMDEGA-b-PS)(3) films in a D2O vapor atmosphere is better than that of films from linear PS-b-PMDEGA-b-PS triblock copolymers, which can be attributed to the hydrophilic end groups and limited size of the PS blocks in (PMDEGA-b-PS)(3). However, the swelling kinetics of the as-prepared (PMDEGA-b-PS)(3) films and the response of the swollen film to a temperature change above the TT are significantly slower than that in the PS-b-PMDEGA-b-PS films, which may be related to the conformation restriction by the star-shape. Unlike in the PS-b-PMDEGA-b-PS films, the amount of residual D2O in the collapsed (PMDEGA-b-PS)(3) films depends on the final temperature. It decreases from (9.7 +/- 0.3)% to (7.0 +/- 0.3)% or (6.0 +/- 0.3)% when the final temperatures are set to 35 degrees C, 45 degrees C and 50 degrees C, respectively. This temperature-dependent reduction of embedded D2O originates from the hindrance of chain conformation from the star-shaped chain architecture. Y1 - 2018 U6 - https://doi.org/10.1039/c8sm00965a SN - 1744-683X SN - 1744-6848 VL - 14 IS - 31 SP - 6582 EP - 6594 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Tuncaboylu, Deniz Ceylan A1 - Friess, Fabian A1 - Wischke, Christian A1 - Lendlein, Andreas T1 - A multifunctional multimaterial system for on-demand protein release JF - Journal of controlled release N2 - In order to provide best control of the regeneration process for each individual patient, the release of protein drugs administered during surgery may need to be timely adapted and/or delayed according to the progress of healing/regeneration. This study aims to establish a multifunctional implant system for a local on-demand release, which is applicable for various types of proteins. It was hypothesized that a tubular multimaterial container kit, which hosts the protein of interest as a solution or gel formulation, would enable on-demand release if equipped with the capacity of diameter reduction upon external stimulation. Using devices from poly(epsilon-caprolactone) networks, it could be demonstrated that a shape-memory effect activated by heat or NIR light enabled on-demand tube shrinkage. The decrease of diameter of these shape-memory tubes (SMT) allowed expelling the payload as demonstrated for several proteins including SDF-1 alpha, a therapeutically relevant chemotactic protein, to achieve e.g. continuous release with a triggered add-on dosing (open tube) or an on-demand onset of bolus or sustained release (sealed tube). Considering the clinical relevance of protein factors in (stem) cell attraction to lesions and the progress in monitoring biomarkers in body fluids, such on-demand release systems may be further explored e.g. in heart, nerve, or bone regeneration in the future. KW - Shape-memory polymer KW - On-demand release KW - Proteins KW - Poly(epsilon-caprolactone) networks KW - Near infrared light triggered shape-recovery Y1 - 2018 U6 - https://doi.org/10.1016/j.jconrel.2018.06.022 SN - 0168-3659 SN - 1873-4995 VL - 284 SP - 240 EP - 247 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wang, Li A1 - Razzaq, Muhammad Yasar A1 - Rudolph, Tobias A1 - Heuchel, Matthias A1 - Nöchel, Ulrich A1 - Mansfeld, Ulrich A1 - Jiang, Yi A1 - Gould, Oliver E. C. A1 - Behl, Marc A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Reprogrammable, magnetically controlled polymeric nanocomposite actuators JF - Material horizons N2 - Soft robots and devices with the advanced capability to perform adaptive motions similar to that of human beings often have stimuli-sensitive polymeric materials as the key actuating component. The external signals triggering the smart polymers’ actuations can be transmitted either via a direct physical connection between actuator and controlling unit (tethered) or remotely without a connecting wire. However, the vast majority of such polymeric actuator materials are limited to one specific type of motion as their geometrical information is chemically fixed. Here, we present magnetically driven nanocomposite actuators, which can be reversibly reprogrammed to different actuation geometries by a solely physical procedure. Our approach is based on nanocomposite materials comprising spatially segregated crystallizable actuation and geometry determining units. Upon exposure to a specific magnetic field strength the actuators’ geometric memory is erased by the melting of the geometry determining units allowing the implementation of a new actuator shape. The actuation performance of the nanocomposites can be tuned and the technical significance was demonstrated in a multi-cyclic experiment with several hundreds of repetitive free-standing shape shifts without losing performance. Y1 - 2018 U6 - https://doi.org/10.1039/c8mh00266e SN - 2051-6347 SN - 2051-6355 VL - 5 IS - 5 SP - 861 EP - 867 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Yang, Guang A1 - Hu, Rongting A1 - Ding, Hong-ming A1 - Kochovski, Zdravko A1 - Mei, Shilin A1 - Lu, Yan A1 - Ma, Yu-qiang A1 - Chen, Guosong A1 - Jiang, Ming T1 - CO2-switchable response of protein microtubules BT - behaviour and mechanism JF - Materials chemistry frontiers N2 - Recently, we proposed a small molecular inducing ligand strategy to assemble proteins into highly-ordered structures via dual non-covalent interactions, i.e. carbohydrate-protein interaction and dimerization of Rhodamine B. Using this approach, artificial protein microtubules were successfully constructed. In this study, we find that these microtubules exhibit a perfect CO2 responsiveness; assembly and disassembly of these microtubules were nicely controlled by the alternative passage of CO2 and N-2. Upon the injection of CO2, a negative net-charged SBA turns into a neutral or positive net-charged SBA, which elongated, to some extent, the effective distance between SBA and Rhodamine B, resulting in the disassociation of the Rhodamine B dimer. Further experimental and simulation results reveal that the CO2-responsive mechanism differs from that of solubility change of the previously reported CO2-responsive synthetic materials. Y1 - 2018 U6 - https://doi.org/10.1039/c8qm00245b SN - 2052-1537 VL - 2 IS - 9 SP - 1642 EP - 1646 PB - Royal Society of Chemistry CY - Cambridge ER -