TY - JOUR A1 - Tadjoung Waffo, Armel Franklin A1 - Yesildag, Cigdem A1 - Caserta, Giorgio A1 - Katz, Sagie A1 - Zebger, Ingo A1 - Lensen, Marga C. A1 - Wollenberger, Ulla A1 - Scheller, Frieder W. A1 - Altintas, Zeynep T1 - Fully electrochemical MIP sensor for artemisinin JF - Sensors and actuators : B, Chemical N2 - This study aims to develop a rapid, sensitive and cost-effective biomimetic electrochemical sensor for artemisinin determination in plant extracts and for pharmacokinetic studies. A novel molecularly imprinted polymer (MIP)based electrochemical sensor was developed by electropolymerization of o-phenylenediamine (o-PD) in the presence of artemisinin on gold wire surface for sensitive detection of artemisinin. The experimental parameters, including selection of functional monomer, polymerization conditions, template extraction after polymerization, influence of pH and buffer were all optimized. Every step of imprinted film synthesis were evaluated by employing voltammetry techniques, surface-enhanced infrared absorption spectroscopy (SEIRAS) and atomic force microscopy (AFM). The specificity was further evaluated by investigating non-specific artemisinin binding on non-imprinted polymer (NIP) surfaces and an imprinting factor of 6.8 was achieved. The artemisinin imprinted polymers using o-PD as functional monomer have provided highly stable and effective binding cavities for artemisinin. Cross-reactivity studies with drug molecules showed that the MIPs are highly specific for artemisinin. The influence of matrix effect was further investigated both in artificial plant matrix and diluted human serum. The results revealed a high affinity of artemisinin-MIP with dissociation constant of 7.3 x 10(-9) M and with a detection limit of 0.01 mu M and 0.02 mu M in buffer and plant matrix, respectively. KW - Electro-synthesized molecularly imprinted polymer KW - o-Phenylenediamine KW - Artemisinin KW - Antimalarial drug detection KW - Electrochemical sensor Y1 - 2018 U6 - https://doi.org/10.1016/j.snb.2018.08.018 SN - 0925-4005 VL - 275 SP - 163 EP - 173 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Lendlein, Andreas A1 - Balk, Maria A1 - Tarazona, Natalia A. A1 - Gould, Oliver E. C. T1 - Bioperspectives for Shape-Memory Polymers as Shape Programmable, Active Materials JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences N2 - Within the natural world, organisms use information stored in their material structure to generate a physical response to a wide variety of environmental changes. The ability to program synthetic materials to intrinsically respond to environmental changes in a similar manner has the potential to revolutionize material science. By designing polymeric devices capable of responsively changing shape or behavior based on information encoded into their structure, we can create functional physical behavior, including a shape memory and an actuation capability. Here we highlight the stimuli-responsiveness and shape-changing ability of biological materials and biopolymer-based materials, plus their potential biomedical application, providing a bioperspective on shape-memory materials. We address strategies to incorporate a shape memory (actuation) function in polymeric materials, conceptualized in terms of its relationship with inputs (environmental stimuli) and outputs (shape change). Challenges and opportunities associated with the integration of several functions in a single material body to achieve multifunctionality are discussed. Finally, we describe how elements that sense, convert, and transmit stimuli have been used to create multisensitive materials. Y1 - 2019 U6 - https://doi.org/10.1021/acs.biomac.9b01074 SN - 1525-7797 SN - 1526-4602 VL - 20 IS - 10 SP - 3627 EP - 3640 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Lendlein, Andreas A1 - Gould, Oliver E. C. T1 - Reprogrammable recovery and actuation behaviour of shape-memory polymers JF - Nature reviews. Materials N2 - Shape memory is the capability of a material to be deformed and fixed into a temporary shape. Recovery of the original shape can then be triggered only by an external stimulus. Shape-memory polymers are highly deformable materials that can be programmed to recover a memorized shape in response to a variety of environmental and spatially localized stimuli as a one-way effect. The shape-memory function can also be generated as a reversible effect enabling actuation behaviour through macroscale deformation and processing, specifically by dictating the macromolecular orientation of actuation units and of the skeleton structure of geometry-determining units in the polymers. Shape-memory polymers can be programmed and reprogrammed into arbitrary shapes. Both recovery and actuation behaviour are reprogrammable. In this Review, we outline the common basis and key differences between the two shape-memory behaviours of polymers in terms of mechanism, fabrication schemes and characterization methods. We discuss which combination of macromolecular architecture and macroscale processing is necessary for coordinated, decentralized and responsive physical behaviour. The extraction of relevant thermomechanical information is described, and design criteria are shown for microscale and macroscale morphologies to gain high levels of recovered or actuation strains as well as on-demand 2D-to-3D shape transformations. Finally, real-world applications and key future challenges are highlighted. Y1 - 2019 U6 - https://doi.org/10.1038/s41578-018-0078-8 SN - 2058-8437 VL - 4 IS - 2 SP - 116 EP - 133 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Müller, Katharina A1 - Foerstendorf, Harald A1 - Steudtner, Robin A1 - Tsushima, Satoru A1 - Kumke, Michael Uwe A1 - Lefèvre, Grégory A1 - Rothe, Jörg A1 - Mason, Harris A1 - Szabó, Zoltán A1 - Yang, Ping A1 - Adam, Christian K. R. A1 - André, Rémi A1 - Brennenstuhl, Katlen A1 - Chiorescu, Ion A1 - Cho, Herman M. A1 - Creff, Gaëlle A1 - Coppin, Frédéric A1 - Dardenne, Kathy A1 - Den Auwer, Christophe A1 - Drobot, Björn A1 - Eidner, Sascha A1 - Hess, Nancy J. A1 - Kaden, Peter A1 - Kremleva, Alena A1 - Kretzschmar, Jerome A1 - Krüger, Sven A1 - Platts, James A. A1 - Panak, Petra A1 - Polly, Robert A1 - Powell, Brian A. A1 - Rabung, Thomas A1 - Redon, Roland A1 - Reiller, Pascal E. A1 - Rösch, Notker A1 - Rossberg, André A1 - Scheinost, Andreas C. A1 - Schimmelpfennig, Bernd A1 - Schreckenbach, Georg A1 - Skerencak-Frech, Andrej A1 - Sladkov, Vladimir A1 - Solari, Pier Lorenzo A1 - Wang, Zheming A1 - Washton, Nancy M. A1 - Zhang, Xiaobin T1 - Interdisciplinary Round-Robin Test on molecular spectroscopy of the U(VI) Acetate System JF - ACS omega / American Chemical Society N2 - A comprehensive molecular analysis of a simple aqueous complexing system. U(VI) acetate. selected to be independently investigated by various spectroscopic (vibrational, luminescence, X-ray absorption, and nuclear magnetic resonance spectroscopy) and quantum chemical methods was achieved by an international round-robin test (RRT). Twenty laboratories from six different countries with a focus on actinide or geochemical research participated and contributed to this scientific endeavor. The outcomes of this RRT were considered on two levels of complexity: first, within each technical discipline, conformities as well as discrepancies of the results and their sources were evaluated. The raw data from the different experimental approaches were found to be generally consistent. In particular, for complex setups such as accelerator-based X-ray absorption spectroscopy, the agreement between the raw data was high. By contrast, luminescence spectroscopic data turned out to be strongly related to the chosen acquisition parameters. Second, the potentials and limitations of coupling various spectroscopic and theoretical approaches for the comprehensive study of actinide molecular complexes were assessed. Previous spectroscopic data from the literature were revised and the benchmark data on the U(VI) acetate system provided an unambiguous molecular interpretation based on the correlation of spectroscopic and theoretical results. The multimethodologic approach and the conclusions drawn address not only important aspects of actinide spectroscopy but particularly general aspects of modern molecular analytical chemistry. Y1 - 2019 U6 - https://doi.org/10.1021/acsomega.9b00164 SN - 2470-1343 VL - 4 IS - 5 SP - 8167 EP - 8177 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - da Silva, Filipe Ferreira A1 - Varella, Marcio T. do N. A1 - Jones, Nykola C. A1 - Hoffmann, Soren Vronning A1 - Denifl, Stephan A1 - Bald, Ilko A1 - Kopyra, Janina T1 - Electron-Induced Reactions in 3-Bromopyruvic Acid JF - Chemistry - a European journal N2 - 3-Bromopyruvic acid (3BP) is a potential anticancer drug, the action of which on cellular metabolism is not yet entirely clear. The presence of a bromine atom suggests that it is also reactive towards low-energy electrons, which are produced in large quantities during tumour radiation therapy. Detailed knowledge of the interaction of 3BP with secondary electrons is a prerequisite to gain a complete picture of the effects of 3BP in different forms of cancer therapy. Herein, dissociative electron attachment (DEA) to 3BP in the gas phase has been studied both experimentally by using a crossed-beam setup and theoretically through scattering and quantum chemical calculations. These results are complemented by a vacuum ultraviolet absorption spectrum. The main fragmentation channel is the formation of Br- close to 0 eV and within several resonant features at 1.9 and 3-8 eV. At low electron energies, Br- formation proceeds through sigma* and pi* shape resonances, and at higher energies through core-excited resonances. It is found that the electron-capture cross-section is clearly increased compared with that of non-brominated pyruvic acid, but, at the same time, fragmentation reactions through DEA are significantly altered as well. The 3BP transient negative ion is subject to a lower number of fragmentation reactions than those of pyruvic acid, which indicates that 3BP could indeed act by modifying the electron-transport chains within oxidative phosphorylation. It could also act as a radio-sensitiser. KW - density functional calculations KW - dissociative electron attachment KW - drug discovery KW - gas-phase reactions KW - sensitizers Y1 - 2019 U6 - https://doi.org/10.1002/chem.201806132 SN - 0947-6539 SN - 1521-3765 VL - 25 IS - 21 SP - 5498 EP - 5506 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zhang, Quanchao A1 - Rudolph, Tobias A1 - Benitez, Alejandro J. A1 - Gould, Oliver E. C. A1 - Behl, Marc A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Temperature-controlled reversible pore size change of electrospun fibrous shape-memory polymer actuator based meshes JF - Smart materials and structures N2 - Fibrous membranes capable of dynamically responding to external stimuli are highly desirable in textiles and biomedical materials, where adaptive behavior is required to accommodate complex environmental changes. For example, the creation of fabrics with temperature-dependent moisture permeability or self-regulating membranes for air filtration is dependent on the development of materials that exhibit a reversible stimuli-responsive pore size change. Here, by imbuing covalently crosslinked poly(ε-caprolactone) (cPCL) fibrous meshes with a reversible bidirectional shape-memory polymer actuation (rbSMPA) we create a material capable of temperature-controlled changes in porosity. Cyclic thermomechanical testing was used to characterize the mechanical properties of the meshes, which were composed of randomly arranged microfibers with diameters of 2.3 ± 0.6 μm giving an average pore size of approx. 10 μm. When subjected to programming strains of εm = 300% and 100% reversible strain changes of εʹrev = 22% ± 1% and 6% ± 1% were measured, with switching temperature ranges of 10 °C–30 °C and 45 °C–60 °C for heating and cooling, respectively. The rbSMPA of cPCL fibrous meshes generated a microscale reversible pore size change of 11% ± 3% (an average of 1.5 ± 0.6 μm), as measured by scanning electron microscopy. The incorporation of a two-way shape-memory actuation capability into fibrous meshes is anticipated to advance the development and application of smart membrane materials, creating commercially viable textiles and devices with enhanced performance and novel functionality. KW - reversible shape-memory effect KW - fiber meshes KW - electrospinning Y1 - 2019 U6 - https://doi.org/10.1088/1361-665X/ab10a1 SN - 0964-1726 SN - 1361-665X VL - 28 IS - 5 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Vishnevetskaya, Natalya S. A1 - Hildebrand, Viet A1 - Nizardo, Noverra Mardhatillah A1 - Ko, Chia-Hsin A1 - Di, Zhenyu A1 - Radulescu, Aurel A1 - Barnsley, Lester C. A1 - Müller-Buschbaum, Peter A1 - Laschewsky, André A1 - Papadakis, Christine M. T1 - All-in-One "Schizophrenic" self-assembly of orthogonally tuned thermoresponsive diblock copolymers JF - Langmuir N2 - Smart, fully orthogonal switching was realized in a highly biocompatible diblock copolymer system with variable trigger-induced aqueous self-assembly. The polymers are composed of nonionic and zwitterionic blocks featuring lower and upper critical solution temperatures (LCSTs and UCSTs). In the system investigated, diblock copolymers from poly(N-isopropyl methacrylamide) (PNIPMAM) and a poly(sulfobetaine methacrylamide), systematic variation of the molar mass of the latter block allowed for shifting the UCST of the latter above the LCST of the PNIPMAM block in a salt-free condition. Thus, successive thermal switching results in "schizophrenic" micellization, in which the roles of the hydrophobic core block and the hydrophilic shell block are interchanged depending on the temperature. Furthermore, by virtue of the strong electrolyte-sensitivity of the zwitterionic polysulfobetaine block, we succeeded to shift its UCST below the LCST of the PNIPMAM block by adding small amounts of an electrolyte, thus inverting the pathway of switching. This superimposed orthogonal switching by electrolyte addition enabled us to control the switching scenarios between the two types of micelles (i) via an insoluble state, if the LCST-type cloud point is below the UCST-type cloud point, which is the case at low salt concentrations or (ii) via a molecularly dissolved state, if the LCST-type cloud point is above the UCST-type cloud point, which is the case at high salt concentrations. Systematic variation of the block lengths allowed for verifying the anticipated behavior and identifying the molecular architecture needed. The versatile and tunable self-assembly offers manifold opportunities, for example, for smart emulsifiers or for sophisticated carrier systems. Y1 - 2019 U6 - https://doi.org/10.1021/acs.langmuir.9b00241 SN - 0743-7463 VL - 35 IS - 19 SP - 6441 EP - 6452 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Liu, Yue A1 - Gould, Oliver E. C. A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Shape-memory actuation of individual micro-/nanofibers JF - MRS Advances N2 - Advances in the fabrication and characterization of polymeric nanomaterials has greatly advanced the miniaturization of soft actuators, creating materials capable of replicating the functional physical behavior previously limited to the macroscale. Here, we demonstrate how a reversible shape-memory polymer actuation can be generated in a single micro/nano object, where the shape change during actuation of an individual fiber can be dictated by programming using an AFM-based method. Electrospinning was used to prepare poly(epsilon-caprolactone) micro-/nanofibers, which were fixed and crosslinked on a structured silicon wafer. The programming as well as the observation of recovery and reversible displacement of the fiber were performed by vertical three point bending, using an AFM testing platform introduced here. A plateau tip was utilized to improve the stability of the fiber contact and working distance, enabling larger deformations and greater rbSMPA performance. Values for the reversible elongation of epsilon(rev)= 3.4 +/- 0.1% and 10.5 +/- 0.1% were obtained for a single micro (d = 1.0 +/- 0.2 mu m) and nanofiber (d = 300 +/- 100 nm) in cyclic testing between the temperatures 10 and 60 degrees C. The reversible actuation of the nanofiber was successfully characterized for 10 cycles. The demonstration and characterization of individual shape-memory nano and microfiber actuators represents an important step in the creation of miniaturized robotic devices capable of performing complex physical functions at the length scale of cells and structural component of the extracellular matrix. Y1 - 2020 U6 - https://doi.org/10.1557/adv.2020.276 SN - 2059-8521 VL - 5 IS - 46-47 SP - 2391 EP - 2399 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Izraylit, Victor A1 - Gould, Oliver E. C. A1 - Kratz, Karl A1 - Lendlein, Andreas T1 - Investigating the phase-morphology of PLLA-PCL multiblock copolymer/PDLA blends cross-linked using stereocomplexation JF - MRS advances N2 - The macroscale function of multicomponent polymeric materials is dependent on their phase-morphology. Here, we investigate the morphological structure of a multiblock copolymer consisting of poly(L-lactide) and poly(epsilon-caprolactone) segments (PLLA-PCL), physically cross-linked by stereocomplexation with a low molecular weight poly(D-lactide) oligomer (PDLA). The effects of blend composition and PLLA-PCL molecular structure on the morphology are elucidated by AFM, TEM and SAXS. We identify the formation of a lattice pattern, composed of PLA domains within a PCL matrix, with an average domain spacing d0 = 12 - 19 nm. The size of the PLA domains were found to be proportional to the block length of the PCL segment of the copolymer and inversely proportional to the PDLA content of the blend. Changing the PLLA-PCL / PDLA ratio caused a shift in the melt transition Tm attributed to the PLA stereocomplex crystallites, indicating partial amorphous phase dilution of the PLA and PCL components within the semicrystalline material. By elucidating the phase structure and thermal character of multifunctional PLLA-PCL / PDLA blends, we illustrate how composition affects the internal structure and thermal properties of multicomponent polymeric materials. This study should facilitate the more effective incorporation of a variety of polymeric structural units capable of stimuli responsive phase transitions, where an understanding the phase-morphology of each component will enable the production of multifunctional soft-actuators with enhanced performance. KW - polymer KW - blend KW - nanostructure KW - morphology Y1 - 2020 U6 - https://doi.org/10.1557/adv.2019.465 SN - 2059-8521 VL - 5 IS - 14-15 SP - 699 EP - 707 PB - Cambridge Univ. Press CY - New York ER - TY - JOUR A1 - Izraylit, Victor A1 - Hommes-Schattmann, Paul Jacob A1 - Neffe, Axel T. A1 - Gould, Oliver E. C. A1 - Lendlein, Andreas T1 - Alkynyl-functionalized chain-extended PCL for coupling to biological molecules JF - European polymer journal N2 - Chemical functionalization of poly(epsilon-caprolactone) (PCL) enables a molecular integration of additional function. Here, we report an approach to incorporate reactive alkynyl side-groups by synthesizing a chain-extended PCL, where the reactive site is introduced through the covalently functionalizable chain extender 3 (prop-2-yn-1-yloxy)propane-1,2-diol (YPD). Chain-extended PCL with M-w of 101 to 385 kg.mol(-1) were successfully synthesized in a one-pot reaction from PCL-diols with various molar masses, L-lysine ethyl ester diisocyanate (LDI) or trimethyl(hexamethylene)diisocyanate (TMDI), and YPD, in which the density of functionalizable groups and spacing between them can be controlled by the composition of the polymer. The employed diisocyanate compounds and YPD possess an asymmetric structure and form a non-crystallizable segment leaving the PCL crystallites to dominate the material's mechanical properties. The mixed glass transition temperature T-g = - 60 to - 46 degrees C of the PCL/polyurethane amorphous phase maintains the synthesized materials in a highly elastic state at ambient and physiological conditions. Reaction conditions for covalent attachment in copper(I)-catalyzed azide-alkyne-cycloaddition reactions (CuAAC) in solution were optimized in a series of model reactions between the alkyne moieties of the chain-extended PCL and benzyl azide, reaching conversions over 95% of the alkyne moieties and with yields of up to 94% for the purified functionalized PCL. This methodology was applied for reaction with the azide-functionalized cell adhesion peptide GRGDS. The required modification of the peptide provides selectivity in the coupling reactions. The obtained results suggest that YPD could potentially be employed as versatile molecular unit for the creation of a variety of functionalizable polyesters as well as polyurethanes and polycarbonates offering efficient and selective click-reactions. KW - copper-catalyzed alkyne-azide cycloaddition KW - chain-extended KW - polycaprolactone KW - RGD-peptide KW - side-chains functionalization Y1 - 2020 U6 - https://doi.org/10.1016/j.eurpolymj.2020.109908 SN - 0014-3057 SN - 1873-1945 VL - 136 PB - Elsevier CY - Oxford ER -