TY  - JOUR
A1  - Garakani, Tayebeh Mirzaei
A1  - Liu, Zhanzhi
A1  - Glebe, Ulrich
A1  - Gehrmann, Julia
A1  - Lazar, Jaroslav
A1  - Mertens, Marie Anna Stephanie
A1  - Möller, Mieke
A1  - Hamzelui, Niloofar
A1  - Zhu, Leilei
A1  - Schnakenberg, Uwe
A1  - Böker, Alexander
A1  - Schwaneberg, Ulrich
T1  - In Situ Monitoring of Membrane Protein Insertion into Block Copolymer Vesicle Membranes and Their Spreading via Potential-Assisted Approach
JF  - ACS applied materials & interfaces
N2  - Synthosomes are polymer vesicles with trans membrane proteins incorporated into block copolymer membranes. They have been used for selective transport in or out of the vesicles as well as catalysis inside the compartments. However, both the insertion process of the membrane protein, forming nanopores, and the spreading of the vesicles on planar substrates to form solid-supported biomimetic membranes have been rarely studied yet. Herein, we address these two points and, first, shed light on the real-time monitoring of protein insertion via isothermal titration calorimetry. Second, the spreading process on different solid supports, namely, SiO2, glass, and gold, via different techniques like spin- and dip-coating as well as a completely new approach of potential-assisted spreading on gold surfaces was studied. While inhomogeneous layers occur via traditional methods, our proposed potential-assisted strategy to induce adsorption of positively charged vesicles by applying negative potential on the electrode leads to remarkable vesicle spreading and their further fusion to form more homogeneous planar copolymer films on gold. The polymer vesicles in our study are formed from amphiphilic copolymers poly(2-methyl oxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyl oxazoline) (PMOXA-b-PDMS-b-PMOXA). Engineered variants of the transmembrane protein ferric hydroxamate uptake protein component A (FhuA), one of the largest beta-barrel channel proteins, are used as model nanopores. The incorporation of FhuA Delta 1-160 is shown to facilitate the vesicle spreading process further. Moreover, high accessibility of cysteine inside the channel was proven by linkage of a fluorescent dye inside the engineered variant FhuA Delta CVFtev and hence preserved functionality of the channels after spreading. The porosity and functionality of the spread synthosomes on the gold plates have been examined by studying the passive ion transport response in the presence of Li+ and ClO4- ions and electrochemical impedance spectroscopy analysis. Our approach to form solid-supported biomimetic membranes via the potential-assisted strategy could be important for the development of new (bio-) sensors and membranes.
KW  - synthosomes
KW  - solid-supported biomimetic membranes
KW  - polymersome spreading
KW  - electrochemical impedance spectroscopy
KW  - FhuA
Y1  - 2019
U6  - https://doi.org/10.1021/acsami.9b09302
SN  - 1944-8244
SN  - 1944-8252
VL  - 11
IS  - 32
SP  - 29276
EP  - 29289
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Friess, Fabian
A1  - Roch, Toralf
A1  - Seifert, Barbara
A1  - Lendlein, Andreas
A1  - Wischke, Christian
T1  - Phagocytosis of spherical and ellipsoidal micronetwork colloids from crosslinked poly(epsilon-caprolactone)
JF  - International Journal of Pharmaceutics
N2  - The effect of non-spherical particle shapes on cellular uptake has been reported as a general design parameter to control cellular recognition of particulate drug carriers. Beside shape, also size and cell-particle ratio should mutually effect phagocytosis. Here, the capability to control cellular uptake of poly(epsilon-caprolactone) (PCL) based polymer micronetwork colloids (MNC), a carrier system that can be transferred to various shapes, is explored in vitro at test conditions allowing multiple cell-particle contacts. PCL-based MNC were synthesized as spheres with a diameter of similar to 6, similar to 10, and 13 mu m, loaded with a fluorescent dye by a specific technique of swelling, redispersion and drying, and transferred into different ellipsoidal shapes by a phantom stretching method. The boundaries of MNC deformability to prolate ellipsoid target shapes were systematically analyzed and found to be at an aspect ratio AR of similar to 4 as obtained by a phantom elongation epsilon(ph) of similar to 150%. Uptake studies with a murine macrophages cell line showed shape dependency of phagocytosis for selected conditions when varying particle sizes (similar to 6 and 10 mu m),and shapes (epsilon(ph): 0, 75 or 150%), cell-particle ratios (1:1, 1:2, 1:10, 1:50), and time points (1-24 h). For larger-sized MNC, there was no significant shape effect on phagocytosis as these particles may associate with more than one cell, thus increasing the possibility of phagocytosis by any of these cells. Accordingly, controlling shape effects on phagocytosis for carriers made from degradable polymers relevant for medical applications requires considering further parameters besides shape, such as kinetic aspects of the exposure and uptake by cells.
KW  - Particle shape
KW  - Phagocytosis
KW  - Macrophage
KW  - Polymer micronetwork colloids
KW  - Poly(epsilon-caprolactone)
Y1  - 2019
U6  - https://doi.org/10.1016/j.ijpharm.2019.118461
SN  - 0378-5173
SN  - 1873-3476
VL  - 567
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - Benzyne - an acetylene- or cumulene-like electronic structure?
JF  - Tetrahedron
N2  - The spatial magnetic properties, through-space NMR shieldings (TSNMRS), of benzyne 1 and analogues (benzene 2, 1,2,3-cyclohexatriene 3, cyclohexen-3-yne 4, cyclohexen-4-yne 5, cyclohexyne 6) have been calculated using the GIAO perturbation method employing the nucleus independent chemical shift (NICS) concept and visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. The TSNMRS values could be employed to compare the diatropic ring current effects of benzene and benzyne, and, when compared with the spatial magnetic properties of the analogues, to answer the question whether the benzyne electronic structure is more acetylene- or cumulene-like, supported by structural data and delta(C-13)/ppm values. (C) 2019 Published by Elsevier Ltd.
KW  - Benzyne-allene or cumulene-like structure
KW  - Trough-space NMR shieldings (TSNMRS)
KW  - NICS
KW  - Iso-chemical shielding surfaces (ICSS)
KW  - Ring current effect
Y1  - 2019
U6  - https://doi.org/10.1016/j.tet.2019.07.011
SN  - 0040-4020
VL  - 75
IS  - 33
SP  - 4663
EP  - 4668
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Schultze, Christiane
A1  - Schmidt, Bernd
T1  - Functionalized Benzofurans via Microwave-Promoted Tandem Claisen-Rearrangement/5-endo-dig Cyclization
JF  - Journal of heterocyclic chemistry
N2  - Ortho-allyloxy alkinyl benzenes undergo, upon microwave irradiation in dimethylformamide, a tandem sequence of Claisen-rearrangement and 5-endo-dig cyclization to furnish 7-allyl-substituted benzofurans. With terminal alkynes, chroman-4-ones and enaminoketones become the main products. A mechanistic proposal for this observation relies on a reaction of the starting material with the solvent dimethylformamide under the microwave conditions.
Y1  - 2019
U6  - https://doi.org/10.1002/jhet.3671
SN  - 0022-152X
SN  - 1943-5193
VL  - 56
IS  - 9
SP  - 2619
EP  - 2629
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Schwarze, Thomas
A1  - Riemer, Janine
A1  - Müller, Holger
A1  - John, Leonard
A1  - Holdt, Hans-Jürgen
A1  - Wessig, Pablo
T1  - Na+ Selective Fluorescent Tools Based on Fluorescence Intensity Enhancements, Lifetime Changes, and on a Ratiometric Response
JF  - Chemistry - a European journal
N2  - Over the years, we developed highly selective fluorescent probes for K+ in water, which show K+-induced fluorescence intensity enhancements, lifetime changes, or a ratiometric behavior at two emission wavelengths (cf. Scheme 1, K1-K4). In this paper, we introduce selective fluorescent probes for Na+ in water, which also show Na+ induced signal changes, which are analyzed by diverse fluorescence techniques. Initially, we synthesized the fluorescent probes 2, 4, 5, 6 and 10 for a fluorescence analysis by intensity enhancements at one wavelength by varying the Na+ responsive ionophore unit and the fluorophore moiety to adjust different K-d values for an intra- or extracellular Na+ analysis. Thus, we found that 2, 4 and 5 are Na+ selective fluorescent tools, which are able to measure physiologically important Na+ levels at wavelengths higher than 500 nm. Secondly, we developed the fluorescent probes 7 and 8 to analyze precise Na+ levels by fluorescence lifetime changes. Herein, only 8 (K-d=106 mm) is a capable fluorescent tool to measure Na+ levels in blood samples by lifetime changes. Finally, the fluorescent probe 9 was designed to show a Na+ induced ratiometric fluorescence behavior at two emission wavelengths. As desired, 9 (K-d=78 mm) showed a ratiometric fluorescence response towards Na+ ions and is a suitable tool to measure physiologically relevant Na+ levels by the intensity change of two emission wavelengths at 404 nm and 492 nm.
KW  - crown compounds
KW  - fluorescence lifetime
KW  - fluorescent probes
KW  - ratiometric
KW  - sodium
Y1  - 2019
U6  - https://doi.org/10.1002/chem.201902536
SN  - 0947-6539
SN  - 1521-3765
VL  - 25
IS  - 53
SP  - 12412
EP  - 12422
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Rosencrantz, Sophia
A1  - Tang, Jo Sing Julia
A1  - Schulte-Osseili, Christine
A1  - Böker, Alexander
A1  - Rosencrantz, Ruben R.
T1  - Glycopolymers by RAFT Polymerization as Functional Surfaces for Galectin-3
JF  - Macromolecular chemistry and physics
N2  - Glycan-protein interactions are essential biological processes with many disease-related modulations and variations. One of the key proteins involved in tumor progression and metastasis is galectin-3 (Gal-3). A lot of effort is put into the development of Gal-3 inhibitors as new therapeutic agents. The avidity of glycan-protein interactions is strongly enhanced by multivalent ligand presentation. Multivalent presentation of glycans can be accomplished by utilizing glycopolymers, which are polymers with pendent glycan groups. For the production of glycopolymers, glycomonomers are synthesized by a regioselective, microwave-assisted approach starting from lactose. The resulting methacrylamide derivatives are polymerized by RAFT and immobilized on gold surfaces using the trithiocarbonate group of the chain transfer agent. Surface plasmon resonance spectroscopy enables the label free kinetic characterization of Gal-3 binding to these multivalent glycopolymers. The measurements indicate oligomerization of Gal-3 upon exposure to multivalent environments and reveal strong specific interaction with the immobilized polymers.
KW  - galectin-3
KW  - glycopolymers
KW  - multivalency
KW  - RAFT
KW  - surface plasmon resonance
Y1  - 2019
U6  - https://doi.org/10.1002/macp.201900293
SN  - 1022-1352
SN  - 1521-3935
VL  - 220
IS  - 20
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Sperling, Marcel
A1  - Reifarth, Martin
A1  - Grobe, Richard
A1  - Böker, Alexander
T1  - Tailoring patches on particles: a modified microcontact printing routine using polymer-functionalised stamps
JF  - Chemical communications
N2  - Herein, we report a modified microcontact printing (mu CP) routine suitable to introduce particle patches of a low molecular weight ink (LMWI) on porous SiO2 microparticles. Thereby, patch precision could be significantly improved by utilising stamps which have been surface-functionalised with grafted polymers. This improvement was evaluated by a profound software-assisted statistical analysis.
Y1  - 2019
U6  - https://doi.org/10.1039/c9cc03903a
SN  - 1359-7345
SN  - 1364-548X
VL  - 55
IS  - 68
SP  - 10104
EP  - 10107
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Balderas-Valadez, Ruth Fabiola
A1  - Schürmann, Robin Mathis
A1  - Pacholski, Claudia
T1  - One Spot-Two Sensors: Porous Silicon Interferometers in Combination With Gold Nanostructures Showing Localized Surface Plasmon Resonance
JF  - Frontiers in chemistry
N2  - Sensors composed of a porous silicon monolayer covered with a film of nanostructured gold layer, which provide two optical signal transduction methods, are fabricated and thoroughly characterized concerning their sensing performance. For this purpose, silicon substrates were electrochemically etched in order to obtain porous silicon monolayers, which were subsequently immersed in gold salt solution facilitating the formation of a porous gold nanoparticle layer on top of the porous silicon. The deposition process was monitored by reflectance spectroscopy, and the appearance of a dip in the interference pattern of the porous silicon layer was observed. This dip can be assigned to the absorption of light by the deposited gold nanostructures leading to localized surface plasmon resonance. The bulk sensitivity of these sensors was determined by recording reflectance spectra in media having different refractive indices and compared to sensors exclusively based on porous silicon or gold nanostructures. A thorough analysis of resulting shifts of the different optical signals in the reflectance spectra on the wavelength scale indicated that the optical response of the porous silicon sensor is not influenced by the presence of a gold nanostructure on top. Moreover, the adsorption of thiol-terminated polystyrene to the sensor surface was solely detected by changes in the position of the dip in the reflectance spectrum, which is assigned to localized surface plasmon resonance in the gold nanostructures. The interference pattern resulting from the porous silicon layer is not shifted to longer wavelengths by the adsorption indicating the independence of the optical response of the two nanostructures, namely porous silicon and nanostructured gold layer, to refractive index changes and pointing to the successful realization of two sensors in one spot.
KW  - porous silicon
KW  - interferometry
KW  - gold nanostructures
KW  - surface plasmon resonance
KW  - optical sensor
Y1  - 2019
U6  - https://doi.org/10.3389/fchem.2019.00593
SN  - 2296-2646
VL  - 7
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Lai, Feili
A1  - Feng, Jianrui
A1  - Heil, Tobias
A1  - Tian, Zhihong
A1  - Schmidt, Johannes
A1  - Wang, Gui-Chang
A1  - Oschatz, Martin
T1  - Partially delocalized charge in Fe-doped NiCo2S4 nanosheet-mesoporous carbon-composites for high-voltage supercapacitors
JF  - Journal of materials chemistry : A, Materials for energy and sustainability
N2  - Unraveling the effect of transition-metal doping on the energy storage properties of bimetallic sulfides remains a grand challenge. Herein, we construct bimetallic sulfide nanosheets and hence deliberately introduce transition-metal doping domains on their surface. The resulting materials show not only an enhanced density of states near the Fermi level but also partially delocalized charge as shown by density functional theory (DFT) calculations. Fe-doped NiCo2S4 nanosheets wrapped on N,S-doped ordered mesoporous carbon (Fe-NiCo2S4@N,S-CMK-3) are prepared, which show an enhanced specific capacitance of 197.8 F g(-1) in ionic liquid-based supercapacitors at a scan rate of 2 mV s(-1). This is significantly higher as compared to the capacitance of 155.2 and 135.9 F g(-1) of non-iron-doped NiCo2S4@N,S-CMK and Fe-NiCo2S4@CMK-3 electrodes, respectively. This result arises from the enhanced ionic liquid polarization effect and transportation ability from the Fe-NiCo2S4 surface and N,S-CMK-3 structure. Furthermore, the importance of matching multi-dimensional structures and ionic liquid ion sizes in the fabrication of asymmetric supercapacitors (ASCs) is demonstrated. As a result, the ASC device exhibits a high energy density of 107.5 W h kg(-1) at a power density of 100 W kg(-1) in a working-voltage window of 4 V when using Fe-NiCo2S4@N,S-CMK-3 and N,S-CMK-3 as positive and negative electrodes, respectively. This work puts forward a new direction to design supercapacitor composite electrodes for efficient ionic liquid coupling.
Y1  - 2019
U6  - https://doi.org/10.1039/c9ta06250e
SN  - 2050-7488
SN  - 2050-7496
VL  - 7
IS  - 33
SP  - 19342
EP  - 19347
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Reinicke, Stefan
A1  - Fischer, Thilo
A1  - Bramski, Julia
A1  - Pietruszka, Jörg
A1  - Böker, Alexander
T1  - Biocatalytically active microgels by precipitation polymerization of N-isopropyl acrylamide in the presence of an enzyme
JF  - RSC Advances
N2  - We present a novel protocol for the synthesis of enzymatically active microgels. The protocol is based on the precipitation polymerization of N-isopropylacrylamide (NIPAm) in the presence of an enzyme and a protein binding comonomer. A basic investigation on the influence of different reaction parameters such as monomer concentration and reaction temperature on the microgel size and size distribution is performed and immobilization yields are determined. Microgels exhibiting hydrodynamic diameters between 100 nm and 1 mu m and narrow size distribution could be synthesized while about 31-44% of the enzyme present in the initial reaction mixture can be immobilized. Successful immobilization including a verification of enzymatic activity of the microgels is achieved for glucose oxidase (GOx) and 2-deoxy-d-ribose-5-phosphate aldolase (DERA). The thermoresponsive properties of the microgels are assessed and discussed in the light of activity evolution with temperature. The positive correlation of enzymatic activity with temperature for the GOx containing microgel originates from a direct interaction of the enzyme with the PNIPAm based polymer matrix whose magnitude is highly influenced by temperature.
Y1  - 2019
U6  - https://doi.org/10.1039/c9ra04000e
SN  - 2046-2069
VL  - 9
IS  - 49
SP  - 28377
EP  - 28386
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Shou, Keyun
A1  - Bremer, Anne
A1  - Rindfleisch, Tobias
A1  - Knox-Brown, Patrick
A1  - Hirai, Mitsuhiro
A1  - Rekas, Agata
A1  - Garvey, Christopher J.
A1  - Hincha, Dirk K.
A1  - Stadler, Andreas M.
A1  - Thalhammer, Anja
T1  - Conformational selection of the intrinsically disordered plant stress protein COR15A in response to solution osmolarity - an X-ray and light scattering study
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - The plant stress protein COR15A stabilizes chloroplast membranes during freezing. COR15A is an intrinsically disordered protein (IDP) in aqueous solution, but acquires an alpha-helical structure during dehydration or the increase of solution osmolarity. We have used small- and wide-angle X-ray scattering (SAXS/WAXS) combined with static and dynamic light scattering (SLS/DLS) to investigate the structural and hydrodynamic properties of COR15A in response to increasing solution osmolarity. Coarse-grained ensemble modelling allowed a structure-based interpretation of the SAXS data. Our results demonstrate that COR15A behaves as a biomacromolecule with polymer-like properties which strongly depend on solution osmolarity. Biomacromolecular self-assembly occurring at high solvent osmolarity is initiated by the occurrence of two specific structural subpopulations of the COR15A monomer. The osmolarity dependent structural selection mechanism is an elegant way for conformational regulation and assembly of COR15A. It highlights the importance of the polymer-like properties of IDPs for their associated biological function.
Y1  - 2019
U6  - https://doi.org/10.1039/c9cp01768b
SN  - 1463-9076
SN  - 1463-9084
VL  - 21
IS  - 34
SP  - 18727
EP  - 18740
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Kuroki, Agnes
A1  - Tchoupa, Arnaud Kengmo
A1  - Hartlieb, Matthias
A1  - Peltier, Raoul
A1  - Locock, Katherine E. S.
A1  - Unnikrishnan, Meera
A1  - Perrier, Sebastien
T1  - Targeting intracellular, multi-drug resistant Staphylococcus aureus with guanidinium polymers by elucidating the structure-activity relationship
JF  - Biomaterials : biomaterials reviews online
N2  - Intracellular persistence of bacteria represents a clinical challenge as bacteria can thrive in an environment protected from antibiotics and immune responses. Novel targeting strategies are critical in tackling antibiotic resistant infections. Synthetic antimicrobial peptides (SAMPs) are interesting candidates as they exhibit a very high antimicrobial activity. We first compared the activity of a library of ammonium and guanidinium polymers with different sequences (statistical, tetrablock and diblock) synthesized by RAFT polymerization against methicillin-resistant S. aureus (MRSA) and methicillin-sensitive strains (MSSA). As the guanidinium SAMPs were the most potent, they were used to treat intracellular S. aureus in keratinocytes. The diblock structure was the most active, reducing the amount of intracellular MSSA and MRSA by two-fold. We present here a potential treatment for intracellular, multi-drug resistant bacteria, using a simple and scalable strategy.
KW  - Antimicrobial
KW  - Intracellular bacteria
KW  - Block copolymers
KW  - RAFT polymerization
Y1  - 2019
U6  - https://doi.org/10.1016/j.biomaterials.2019.119249
SN  - 0142-9612
SN  - 1878-5905
VL  - 217
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Walczak, Ralf
A1  - Savateev, Aleksandr
A1  - Heske, Julian
A1  - Tarakina, Nadezda V.
A1  - Sahoo, Sudhir
A1  - Epping, Jan D.
A1  - Kuehne, Thomas D.
A1  - Kurpil, Bogdan
A1  - Antonietti, Markus
A1  - Oschatz, Martin
T1  - Controlling the strength of interaction between carbon dioxide and nitrogen-rich carbon materials by molecular design
JF  - Sustainable energy & fuels
N2  - Thermal treatment of hexaazatriphenylene-hexacarbonitrile (HAT-CN) in the temperature range from 500 degrees C to 700 degrees C leads to precise control over the degree of condensation, and thus atomic construction and porosity of the resulting C2N-type materials. Depending on the condensation temperature of HAT-CN, nitrogen contents of more than 30 at% can be reached. In general, these carbons show adsorption properties which are comparable to those known for zeolites but their pore size can be adjusted over a wider range. At condensation temperatures of 525 degrees C and below, the uptake of nitrogen gas remains negligible due to size exclusion, but the internal pores are large and polarizing enough that CO2 can still adsorb on part of the internal surface. This leads to surprisingly high CO2 adsorption capacities and isosteric heat of adsorption of up to 52 kJ mol(-1). Theoretical calculations show that this high binding enthalpy arises from collective stabilization effects from the nitrogen atoms in the C2N layers surrounding the carbon atom in the CO2 molecule and from the electron acceptor properties of the carbon atoms from C2N which are in close proximity to the oxygen atoms in CO2. A true CO2 molecular sieving effect is achieved for the first time in such a metal-free organic material with zeolite-like properties, showing an IAST CO2/N-2 selectivity of up to 121 at 298 K and a N-2/CO2 ratio of 90/10 without notable changes in the CO2 adsorption properities over 80 cycles.
Y1  - 2019
U6  - https://doi.org/10.1039/c9se00486f
SN  - 2398-4902
VL  - 3
IS  - 10
SP  - 2819
EP  - 2827
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Jia, He
A1  - Quan, Ting
A1  - Liu, Xuelian
A1  - Bai, Lu
A1  - Wang, Jiande
A1  - Boujioui, Fadoi
A1  - Ye, Ran
A1  - Vald, Alexandru
A1  - Lu, Yan
A1  - Gohy, Jean-Francois
T1  - Core-shell nanostructured organic redox polymer cathodes with superior performance
JF  - Nano Energy
N2  - Core-shell nanoparticles stabilized by a cationic surfactant are prepared from the poly(2,2,6,6-tetra-methylpiperidinyloxy-4-yl methacrylate) redox polymer. The nanoparticles are further self-assembled with negatively charged reduced graphene oxide nanosheets and negatively charged mull-walled carbon nanotubes. This results in the formation of a free-standing cathode with a layered nanostructure and a high content of redox polymer that exhibits 100% utilization of the active substance with a measured capacity as high as 105 mAh/g based on the whole weight of the electrode.
KW  - Nanostructured
KW  - Redox polymer
KW  - Organic electrode
KW  - Lithium ion battery
KW  - Energy storage
Y1  - 2019
U6  - https://doi.org/10.1016/j.nanoen.2019.103949
SN  - 2211-2855
SN  - 2211-3282
VL  - 64
PB  - Elsevier
CY  - Amsterdam
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  - Miedema, Piter S.
A1  - Thielemann-Kühn, Nele
A1  - Calafell, Irati Alonso
A1  - Schüßler-Langeheine, Christian
A1  - Beye, Martin
T1  - Strain analysis from M-edge resonant inelastic X-ray scattering of nickel oxide films
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Electronic structure modifications due to strain are an effective method for tailoring nano-scale functional materials. Demonstrated on nickel oxide (NiO) thin films, Resonant Inelastic X-ray Scattering (RIXS) at the transition-metal M-2,M-3-edge is shown to be a powerful tool for measuring the electronic structure modification due to strain in the near-surface region. Analyses from the M-2,M-3-edge RIXS in comparison with dedicated crystal field multiplet calculations show distortions in 40 nm NiO grown on a magnesium oxide (MgO) substrate (NiO/MgO) similar to those caused by surface relaxation of bulk NiO. The films of 20 and 10 nm NiO/MgO show slightly larger differences from bulk NiO. Quantitatively, the NiO/MgO samples all are distorted from perfect octahedral (O-h) symmetry with a tetragonal parameter Ds of about -0.1 eV, very close to the Ds distortion from octahedral (O-h) symmetry parameter of -0.11 eV obtained for the surface-near region from a bulk NiO crystal. Comparing the spectra of a 20 nm film of NiO grown on a 20 nm magnetite (Fe3O4) film on a MgO substrate (NiO/Fe3O4/MgO) with the calculated multiplet analyses, the distortion parameter Ds appears to be closer to zero, showing that the surface-near region of this templated film is less distorted from O-h symmetry than the surface-near region in bulk NiO. Finally, the potential of M-2,M-3-edge RIXS for other investigations of strain on electronic structure is discussed.
Y1  - 2019
U6  - https://doi.org/10.1039/c9cp03593a
SN  - 1463-9076
SN  - 1463-9084
VL  - 21
IS  - 38
SP  - 21596
EP  - 21602
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Xiong, Tao
A1  - Saalfrank, Peter
T1  - Vibrationally Broadened Optical Spectra of Selected Radicals and Cations Derived from Adamantane: A Time-Dependent Correlation Function Approach
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - Diamondoids are hydrogen-saturated molecular motifs cut out of diamond, forming a class of materials with tunable optoelectronic properties. In this work, we extend previous work on neutral, closed-shell diamondoids by computing with hybrid density functional theory and time-dependent correlation functions vibrationally broadened absorption spectra of cations and radicals derived from the simplest diamondoid, adamantane, namely, the neutral 1- and 2-adamantyl radicals (C10H15), the 1- and 2-adamantyl cations (C10H15+), and the adamantane radical cation (C10H16+). For selected cases, we also report vibrationally broadened emission, photoelectron, and resonance Raman spectra. Furthermore, the effect of the damping factor on the vibrational fine-structure is studied. The following trends are found: (1) Low-energy absorptions of the adamantyl radicals and cations, and of the adamantane cation, are all strongly red-shifted with respect to adamantane; (2) also, emission spectra are strongly red-shifted, whereas photoelectron spectra are less affected for the cases studied; (3) vibrational fine-structures are reduced compared to those of adamantane; (4) the spectroscopic signals of 1- and 2-adamantyl species are significantly different from each other; and (5) reducing the damping factor has only a limited effect on the vibrational fine-structure in most cases. This suggests that removing hydrogen atoms and/or electrons from adamantane leads to new optoelectronic properties, which should be detectable by vibronic spectroscopy.
Y1  - 2019
U6  - https://doi.org/10.1021/acs.jpca.9b03305
SN  - 1089-5639
SN  - 1520-5215
VL  - 123
IS  - 41
SP  - 8871
EP  - 8880
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Sass, Stephan
A1  - Stöcklein, Walter F. M.
A1  - Klevesath, Anja
A1  - Hurpin, Jeanne
A1  - Menger, Marcus
A1  - Hille, Carsten
T1  - Binding affinity data of DNA aptamers for therapeutic anthracyclines from microscale thermophoresis and surface plasmon resonance spectroscopy
JF  - The analyst : the analytical journal of the Royal Society of Chemistry
N2  - Anthracyclines like daunorubicin (DRN) and doxorubicin (DOX) play an undisputed key role in cancer treatment, but their chronic administration can cause severe side effects. For precise anthracycline analytical systems, aptamers are preferable recognition elements. Here, we describe the detailed characterisation of a single-stranded DNA aptamer DRN-10 and its truncated versions for DOX and DRN detection. Binding affinities were determined from surface plasmon resonance (SPR) and microscale thermophoresis (MST) and combined with conformational data from circular dichroism (CD). Both aptamers displayed similar nanomolar binding affinities to DRN and DOX, even though their rate constants differed as shown by SPR recordings. SPR kinetic data unravelled a two-state reaction model including a 1 : 1 binding and a subsequent conformational change of the binding complex. This model was supported by CD spectra. In addition, the dissociation constants determined with MST were always lower than that from SPR, and especially for the truncated aptamer they differed by two orders of magnitude. This most probably reflects the methodological difference, namely labelling for MST vs. immobilisation for SPR. From CD recordings, we suggested a specific G-quadruplex as structural basis for anthracycline binding. We concluded that the aptamer DRN-10 is a promising recognition element for anthracycline detection systems and further selected aptamers can be also characterised with the combined methodological approach presented here.
Y1  - 2019
U6  - https://doi.org/10.1039/c9an01247h
SN  - 0003-2654
SN  - 1364-5528
VL  - 144
IS  - 20
SP  - 6064
EP  - 6073
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Kopyshev, Alexey
A1  - Kanevche, Katerina
A1  - Lomadze, Nino
A1  - Pfitzner, Emanuel
A1  - Loebner, Sarah
A1  - Patil, Rohan R.
A1  - Genzer, Jan
A1  - Heberle, Joachim
A1  - Santer, Svetlana
T1  - Light-Induced Structuring of Photosensitive Polymer Brushes
JF  - ACS Applied polymer materials
N2  - We investigate light-induced irreversible structuring of surface topographies in poly(3-sulfopropyl methacrylate/potassium salt) (PSPMK) brushes on flat solid substrates prepared by surface-initiated atom transfer radical polymerization. The brushes have been loaded with azobenzene-based surfactant comprised of positively charged headgroups and hydrophobic tail. The surfactant exhibits photoresponsive properties through photoisomerization from the trans to cis states leading to significant changes in physicochemical properties of grafted polymer chains. The azobenzene surfactant enables photoresponsive behavior without introducing irreversible changes to chemical composition of the parent polymer brush. Exposing these photosensitive brushes to irradiation with UV interference beams causes the polymer brush to form surface relief grating (SRG) patterns. The cationic surfactant penetrates only similar to 25% of the upper portion of the PSPMK brush, resulting in the formation of two sections within the brush: a photoresponsive upper layer and nonfunctional buried layer, which is not affected by the UV irradiation. Using nano-FTIR spectroscopy, we characterize locally the chemical composition of the polymer brush and confirm partial penetration of the surfactant within the film. Strong optomechanical stresses take place only within the upper layer of the brush that is impregnated with the surfactants and causes surface topography alternation due to a local rupture of grafted polymer chains. The cleaved polymer chains are then removed from the surface by using a good solvent, leaving behind topographical grating on top of the nonfunctional brush layer. We demonstrate that photostructured polymer brush can be used for reversible switching of brush topography by varying external humidity.
KW  - photosensitive polymer brushes
KW  - reversible and irreversible structuring of polymer brushes
KW  - photosensitive azobenzene containing surfactant
KW  - strong polyelectrolyte brush
KW  - SRG formation in polymer brushes
Y1  - 2019
U6  - https://doi.org/10.1021/acsapm.9b00705
SN  - 2637-6105
VL  - 1
IS  - 11
SP  - 301
EP  - 3026
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Qin, Qing
A1  - Heil, T.
A1  - Schmidt, J.
A1  - Schmallegger, Max
A1  - Gescheidt, Georg
A1  - Antonietti, Markus
A1  - Oschatz, Martin
T1  - Electrochemical Fixation of Nitrogen and Its Coupling with Biomass Valorization with a Strongly Adsorbing and Defect Optimized Boron-Carbon-Nitrogen Catalyst
JF  - ACS Applied Energy Materials
N2  - The electrochemical conversion of low-cost precursors into high-value chemicals using renewably generated electricity is a promising approach to build up an environmentally friendly energy cycle, including a storage element. The large-scale implementation of such process can, however, only be realized by the design of cost-effective electrocatalysts with high efficiency and highest stability. Here, we report the synthesis of N and B codoped porous carbons. The constructed B-N motives combine abundant unpaired electrons and frustrated Lewis pairs (FLPs). They result in desirable performance for electrochemical N-2 reduction reaction (NRR) and electrooxidation of 5-hydroxymethylfurfural (HMF) in the absence of any metal cocatalyst. A maximum Faradaic efficiency of 15.2% with a stable NH3 production rate of 21.3 mu g h(-1) mg(-1) is obtained in NRR. Besides, 2,5-furandicarboxylic acid (FDCA) is first obtained by using non-metalbased electrocatalysts at a conversion of 71% and with yield of 57%. Gas adsorption experiments elucidate the relationship between the structure and the ability of the catalysts to activate the substrate molecules. This work opens up deep insights for the rational design of non-metal-based catalysts for potential electrocatalytic applications and the possible enhancement of their activity by the introduction of FLPs and point defects at grain boundaries.
KW  - non-metal catalysis
KW  - porous carbon
KW  - heteroatoms
KW  - N-2 reduction
KW  - HMF oxidation
Y1  - 2019
U6  - https://doi.org/10.1021/acsaem.9b01852
SN  - 2574-0962
VL  - 2
IS  - 11
SP  - 8359
EP  - 8365
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Yang, Guang
A1  - Zheng, Wei
A1  - Tao, Guoqing
A1  - Wu, Libin
A1  - Zhou, Qi-Feng
A1  - Kochovski, Zdravko
A1  - Ji, Tan
A1  - Chen, Huaijun
A1  - Li, Xiaopeng
A1  - Lu, Yan
A1  - Ding, Hong-ming
A1  - Yang, Hai-Bo
A1  - Chen, Guosong
A1  - Jiang, Ming
T1  - Diversiform and Transformable Glyco-Nanostructures Constructed from Amphiphilic Supramolecular Metallocarbohydrates through Hierarchical Self-Assembly: The Balance between Metallacycles and Saccharides
JF  - ACS nano
N2  - During the past decade, self-assembly of saccharide-containing amphiphilic molecules toward bioinspired functional glycomaterials has attracted continuous attention due to their various applications in fundamental and practical areas. However, it still remains a great challenge to prepare hierarchical glycoassemblies with controllable and diversiform structures because of the complexity of saccharide structures and carbohydrate-carbohydrate interactions. Herein, through hierarchical self-assembly of modulated amphiphilic supramolecular metallocarbohydrates, we successfully prepared various well-defined glyco-nanostructures in aqueous solution, including vesicles, solid spheres, and opened vesicles depending on the molecular structures of metallocarbohydrates. More attractively, these glyco-nanostructures can further transform into other morphological structures in aqueous solutions such as worm-like micelles, tubules, and even tupanvirus-like vesicles (TVVs). It is worth mentioning that distinctive anisotropic structures including the opened vesicles (OVs) and TVVs were rarely reported in glycobased nano-objects. This intriguing diversity was mainly controlled by the subtle structural trade-off of the two major components of the amphiphiles, i.e., the saccharides and metallacycles. To further understand this precise structural control, molecular simulations provided deep physical insights on the morphology evolution and balancing of the contributions from saccharides and metallacycles. Moreover, the multivalency of glyco-nanostructures with different shapes and sizes was demonstrated by agglutination with a diversity of sugarbinding protein receptors such as the plant lectins Concanavalin A (ConA). This modular synthesis strategy provides access to systematic tuning of molecular structure and self-assembled architecture, which undoubtedly will broaden our horizons on the controllable fabrication of biomimetic glycomaterials such as biological membranes and supramolecular lectin inhibitors.
KW  - glycomaterials
KW  - diversiform structures
KW  - hierarchical self-assembly
KW  - metallocarbohydrates
KW  - anisotropic structures
Y1  - 2019
U6  - https://doi.org/10.1021/acsnano.9b07134
SN  - 1936-0851
SN  - 1936-086X
VL  - 13
IS  - 11
SP  - 13474
EP  - 13485
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Suslova, Elena N.
A1  - Tran Dinh Phien, 
A1  - Shlykov, Sergey A.
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
T1  - 1-Methylthio-1-phenyl-1-silacyclohexane: Synthesis, conformational preferences in gas and solution by GED, NMR and theoretical calculations
JF  - Tetrahedron
N2  - 1-Methylthio-1-phenyl-1-silacyclohexane 1, the first silacyclohexane with the sulfur atom at silicon, was synthesized and its molecular structure and conformational preferences studied by gas-phase electron diffraction (GED) and low temperature C-13 and Si-29 NMR spectroscopy (LT NMR). Quantum-chemical calculations were carried out both for the isolated species and solvate complexes in gas and in polar medium. The predominance of the 1-MeSaxPheq conformer in gas phase (1-Ph-eq :1-Ph-ax = 55:45, Delta G degrees = 0.13 kcal/mol) determined from GED is consistent with that measured in the freon solution by LT NMR (1-Ph-eq:1-Ph-ax = 65:35, Delta G degrees = 0.12 kcal/mol), the experimentally measured ratios being close to that estimated by quantum chemical calculations at both the DFT and MP2 levels of theory. (C) 2019 Elsevier Ltd. All rights reserved.
KW  - 1-Methylthio-1-phenyl-1-silacyclohexane
KW  - Conformational analysis
KW  - Gas phase electron diffraction
KW  - Low-temperature C-13 and Si-29 NMR
KW  - DFT and MP2 calculations
Y1  - 2019
U6  - https://doi.org/10.1016/j.tet.2019.130677
SN  - 0040-4020
VL  - 75
IS  - 46
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Otte, Fabian
A1  - Schmidt, Bernd
T1  - Matsuda-Heck Arylation of Glycals for the Stereoselective Synthesis of Aryl C-Glycosides
JF  - The journal of organic chemistry
N2  - The methoxymethyl-protected glycal L-amicetal, synthesized de novo from L-ethyl lactate through tandem ring-closing metathesis-isomerization sequence, undergoes a highly trans-diastereoselective Heck-type coupling reaction with various arene diazonium salts to furnish 2,3-unsaturated aryl C-glycosides in moderate to excellent yields. The products can be further functionalized, e.g., by hydrogenation, epoxidation, or dihydroxylation to furnish 2,3,6-tridesoxy, 2,3-anhydro-6-desoxy, or 6-desoxy aryl C-glycosides, respectively. The method was applied to the synthesis of an a-configured 6-desoxy-gliflozin derivative.
Y1  - 2019
U6  - https://doi.org/10.1021/acs.joc.9b02410
SN  - 0022-3263
SN  - 1520-6904
VL  - 84
IS  - 22
SP  - 14816
EP  - 14829
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Aloni, Sapir Shekef
A1  - Perovic, Milena
A1  - Weitman, Michal
A1  - Cohen, Reut
A1  - Oschatz, Martin
A1  - Mastai, Yitzhak
T1  - Amino acid-based ionic liquids as precursors for the synthesis of chiral nanoporous carbons
JF  - Nanoscale Advances
N2  - The synthesis of chiral nanoporous carbons based on chiral ionic liquids (CILs) of amino acids as precursors is described. Such unique precursors for the carbonization of CILs yield chiral carbonaceous materials with high surface area (approximate to 620 m(2) g(-1)). The enantioselectivities of the porous carbons are examined by advanced techniques such as selective adsorption of enantiomers using cyclic voltammetry, isothermal titration calorimetry, and mass spectrometry. These techniques demonstrate the chiral nature and high enantioselectivity of the chiral carbon materials. Overall, we believe that the novel approach presented here can contribute significantly to the development of new chiral carbon materials that will find important applications in chiral chemistry, such as in chiral catalysis and separation and in chiral sensors. From a scientific point of view, the approach and results reported here can significantly deepen our understanding of chirality at the nanoscale and of the structure and nature of chiral nonporous materials and surfaces.
Y1  - 2019
U6  - https://doi.org/10.1039/c9na00520j
SN  - 2516-0230
VL  - 1
IS  - 12
SP  - 4981
EP  - 4988
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Zehbe, Kerstin
A1  - Lange, Alyna
A1  - Taubert, Andreas
T1  - Stereolithography Provides Access to 3D Printed lonogels with High Ionic Conductivity
JF  - Energy Fuels
N2  - New ionogels (IGs) were prepared by combination of a series of sulfonate-based ionic liquids (ILs), 1-methyl-3-(4-sulfobutyl)imidazolium para-toluenesulfonate [BmimSO(3)][pTS], 1-methyl-1-butylpiperidiniumsulfonate para-toluenesul-fonate [BmpipSO(3)] [pTS], and 1-methyl-3-(4-sulfobutyl) imidazolium methylsulfonate [BmimSO(3)H][MeSO3] with a commercial stereolithography photoreactive resin. The article describes both the fundamental properties of the ILs and the resulting IGs. The IGs obtained from the ILs and the resin show high ionic conductivity of up to ca. 0.7.10(-4) S/cm at room temperature and 3.4-10(-3) S/cm at 90 degrees C. Moreover, the IGs are thermally stable to about 200 degrees C and mechanically robust. Finally, and most importantly, the article demonstrates that the IGs can be molded three-dimensionally using stereolithography. This provides, for the first time, access to IGs with complex 3D shapes with potential application in battery or fuel cell technology.
Y1  - 2019
U6  - https://doi.org/10.1021/acs.energyfuels.9b03379
SN  - 0887-0624
SN  - 1520-5029
VL  - 33
IS  - 12
SP  - 12885
EP  - 12893
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Taubert, Andreas
A1  - Leroux, Fabrice
A1  - Rabu, Pierre
A1  - de Zea Bermudez, Veronica
T1  - Advanced hybrid nanomaterials
JF  - Beilstein journal of nanotechnology
KW  - colloidal chemistry
KW  - environmental remediation
KW  - hybrid nanomaterials
KW  - nanocomposite
KW  - nanofillers
KW  - nanomedicine
KW  - nanostructures
KW  - polymer fillers
KW  - pore templating
KW  - smart materials
Y1  - 2019
U6  - https://doi.org/10.3762/bjnano.10.247
SN  - 2190-4286
VL  - 10
SP  - 2563
EP  - 2567
PB  - Beilstein-Institut zur Förderung der Chemischen Wissenschaften
CY  - Frankfurt am Main
ER  - 
TY  - JOUR
A1  - Günther, Erika
A1  - Klauß, André
A1  - Toro-Nahuelpan, Mauricio
A1  - Schüler, Dirk
A1  - Hille, Carsten
A1  - Faivre, Damien
T1  - The in vivo mechanics of the magnetotactic backbone as revealed by correlative FLIM-FRET and STED microscopy
JF  - Scientific reports
N2  - Protein interaction and protein imaging strongly benefit from the advancements in time-resolved and superresolution fluorescence microscopic techniques. However, the techniques were typically applied separately and ex vivo because of technical challenges and the absence of suitable fluorescent protein pairs. Here, we show correlative in vivo fluorescence lifetime imaging microscopy Forster resonance energy transfer (FLIM-FRET) and stimulated emission depletion (STED) microscopy to unravel protein mechanics and structure in living cells. We use magnetotactic bacteria as a model system where two proteins, MamJ and MamK, are used to assemble magnetic particles called magnetosomes. The filament polymerizes out of MamK and the magnetosomes are connected via the linker MamJ. Our system reveals that bacterial filamentous structures are more fragile than the connection of biomineralized particles to this filament. More importantly, we anticipate the technique to find wide applicability for the study and quantification of biological processes in living cells and at high resolution.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-55804-5
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Scholz, Robert
A1  - Lindner, Steven
A1  - Loncaric, Ivor
A1  - Tremblay, Jean Christophe
A1  - Juaristi, J.
A1  - Alducin, Maite
A1  - Saalfrank, Peter
T1  - Vibrational response and motion of carbon monoxide on Cu(100) driven by femtosecond laser pulses: Molecular dynamics with electronic friction
JF  - Physical review : B, Condensed matter and materials physics
N2  - Carbon monoxide on copper surfaces continues to be a fascinating, rich microlab for many questions evolving in surface science. Recently, hot-electron mediated, femtosecond-laser pulse induced dynamics of CO molecules on Cu(100) were the focus of experiments [Inoue et al., Phys. Rev. Lett. 117, 186101 (2016)] and theory [Novko et al., Phys. Rev. Lett. 122, 016806 (2019)], unraveling details of the vibrational nonequilibrium dynamics on ultrashort (subpicoseconds) timescales. In the present work, full-dimensional time-resolved hot-electron driven dynamics are studied by molecular dynamics with electronic friction (MDEF). Dissipation is included by a friction term in a Langevin equation which describes the coupling of molecular degrees of freedom to electron-hole pairs in the copper surface, calculated from gradient-corrected density functional theory (DFT) via a local density friction approximation (LDFA). Relaxation due to surface phonons is included by a generalized Langevin oscillator model. The hot-electron induced excitation is described via a time-dependent electronic temperature, the latter derived from an improved two-temperature model. Our parameter-free simulations on a precomputed potential energy surface allow for excellent statistics, and the observed trends are confirmed by on-the-fly ab initio molecular dynamics with electronic friction (AIMDEF) calculations. By computing time-resolved frequency maps for selected molecular vibrations, instantaneous frequencies, probability distributions, and correlation functions, we gain microscopic insight into hot-electron driven dynamics and we can relate the time evolution of vibrational internal CO stretch-mode frequencies to measured data, notably an observed redshift. Quantitatively, the latter is found to be larger in MDEF than in experiment and possible reasons are discussed for this observation. In our model, in addition we observe the excitation and time evolution of large-amplitude low-frequency modes, lateral CO surface diffusion, and molecular desorption. Effects of surface atom motion and of the laser fluence are also discussed.
Y1  - 2019
U6  - https://doi.org/10.1103/PhysRevB.100.245431
SN  - 2469-9950
SN  - 2469-9969
VL  - 100
IS  - 24
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Burek, Katja
A1  - Dengler, Joachim
A1  - Emmerling, Franziska
A1  - Feldmann, Ines
A1  - Kumke, Michael Uwe
A1  - Stroh, Julia
T1  - Lanthanide Luminescence Revealing the Phase Composition in Hydrating Cementitious Systems
JF  - ChemistryOpen
N2  - The hydration process of Portland cement in a cementitious system is crucial for development of the high‐quality cement‐based construction material. Complementary experiments of X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM) and time‐resolved laser fluorescence spectroscopy (TRLFS) using europium (Eu(III)) as an optical probe are used to analyse the hydration process of two cement systems in the absence and presence of different organic admixtures. We show that different analysed admixtures and the used sulphate carriers in each cement system have a significant influence on the hydration process, namely on the time‐dependence in the formation of different hydrate phases of cement. Moreover, the effect of a particular admixture is related to the type of sulphate carrier used. The quantitative information on the amounts of the crystalline cement paste components is accessible via XRD analysis. Distinctly different morphologies of ettringite and calcium−silicate−hydrates (C−S−H) determined by SEM allow visual conclusions about formation of these phases at particular ageing times. The TRLFS data provides information about the admixture influence on the course of the silicate reaction. The dip in the dependence of the luminescence decay times on the hydration time indicates the change in the structure of C−S−H in the early hydration period. Complementary information from XRD, SEM and TRLFS provides detailed information on distinct periods of the cement hydration process.
KW  - cement admixtures
KW  - cement hydration
KW  - Europium
KW  - luminescence
KW  - SEM
KW  - X-ray diffraction
Y1  - 2019
U6  - https://doi.org/10.1002/open.201900249
SN  - 2191-1363
VL  - 8
IS  - 12
SP  - 1441
EP  - 1452
PB  - Wiley-VCH-Verl.
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Riebe, Daniel
A1  - Erler, Alexander
A1  - Brinkmann, Pia
A1  - Beitz, Toralf
A1  - Löhmannsröben, Hans-Gerd
A1  - Gebbers, Robin
T1  - Comparison of Calibration Approaches in Laser-Induced Breakdown Spectroscopy for Proximal Soil Sensing in Precision Agriculture
JF  - Sensors
N2  - The lack of soil data, which are relevant, reliable, affordable, immediately available, and sufficiently detailed, is still a significant challenge in precision agriculture. A promising technology for the spatial assessment of the distribution of chemical elements within fields, without sample preparation is laser-induced breakdown spectroscopy (LIBS). Its advantages are contrasted by a strong matrix dependence of the LIBS signal which necessitates careful data evaluation. In this work, different calibration approaches for soil LIBS data are presented. The data were obtained from 139 soil samples collected on two neighboring agricultural fields in a quaternary landscape of northeast Germany with very variable soils. Reference analysis was carried out by inductively coupled plasma optical emission spectroscopy after wet digestion. The major nutrients Ca and Mg and the minor nutrient Fe were investigated. Three calibration strategies were compared. The first method was based on univariate calibration by standard addition using just one soil sample and applying the derived calibration model to the LIBS data of both fields. The second univariate model derived the calibration from the reference analytics of all samples from one field. The prediction is validated by LIBS data of the second field. The third method is a multivariate calibration approach based on partial least squares regression (PLSR). The LIBS spectra of the first field are used for training. Validation was carried out by 20-fold cross-validation using the LIBS data of the first field and independently on the second field data. The second univariate method yielded better calibration and prediction results compared to the first method, since matrix effects were better accounted for. PLSR did not strongly improve the prediction in comparison to the second univariate method.
KW  - laser-induced breakdown spectroscopy
KW  - LIBS
KW  - proximal soil sensing
KW  - soil nutrients
KW  - elemental composition
Y1  - 2019
U6  - https://doi.org/10.3390/s19235244
SN  - 1424-8220
VL  - 19
IS  - 23
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Büchele, Dominique
A1  - Chao, Madlen
A1  - Ostermann, Markus
A1  - Leenen, Matthias
A1  - Bald, Ilko
T1  - Multivariate chemometrics as a key tool for prediction of K and Fe in a diverse German agricultural soil-set using EDXRF
JF  - Scientific Reports
N2  - Within the framework of precision agriculture, the determination of various soil properties is moving into focus, especially the demand for sensors suitable for in-situ measurements. Energy-dispersive X-ray fluorescence (EDXRF) can be a powerful tool for this purpose. In this study a huge diverse soil set (n = 598) from 12 different study sites in Germany was analysed with EDXRF. First, a principal component analysis (PCA) was performed to identify possible similarities among the sample set. Clustering was observed within the four texture classes clay, loam, silt and sand, as clay samples contain high and sandy soils low iron mass fractions. Furthermore, the potential of uni- and multivariate data evaluation with partial least squares regression (PLSR) was assessed for accurate determination of nutrients in German agricultural samples using two calibration sample sets. Potassium and iron were chosen for testing the performance of both models. Prediction of these nutrients in 598 German soil samples with EDXRF was more accurate using PLSR which is confirmed by a better overall averaged deviation and PLSR should therefore be preferred.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-53426-5
SN  - 2045-2322
VL  - 9
PB  - Macmillan Publishers Limited, part of Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Liebig, Ferenc
A1  - Henning, Ricky
A1  - Sarhan, Radwan Mohamed
A1  - Prietzel, Claudia Christina
A1  - Schmitt, Clemens Nikolaus Zeno
A1  - Bargheer, Matias
A1  - Koetz, Joachim
T1  - A simple one-step procedure to synthesise gold nanostars in concentrated aqueous surfactant solutions
JF  - RSC Advances
N2  - Due to the enhanced electromagnetic field at the tips of metal nanoparticles, the spiked structure of gold nanostars (AuNSs) is promising for surface-enhanced Raman scattering (SERS). Therefore, the challenge is the synthesis of well designed particles with sharp tips. The influence of different surfactants, i.e., dioctyl sodium sulfosuccinate (AOT), sodium dodecyl sulfate (SDS), and benzylhexadecyldimethylammonium chloride (BDAC), as well as the combination of surfactant mixtures on the formation of nanostars in the presence of Ag⁺ ions and ascorbic acid was investigated. By varying the amount of BDAC in mixed micelles the core/spike-shell morphology of the resulting AuNSs can be tuned from small cores to large ones with sharp and large spikes. The concomitant red-shift in the absorption toward the NIR region without losing the SERS enhancement enables their use for biological applications and for time-resolved spectroscopic studies of chemical reactions, which require a permanent supply with a fresh and homogeneous solution. HRTEM micrographs and energy-dispersive X-ray (EDX) experiments allow us to verify the mechanism of nanostar formation according to the silver underpotential deposition on the spike surface in combination with micelle adsorption.
KW  - optical-properties
KW  - nanoparticles
KW  - sers
KW  - ultrafast
KW  - size
KW  - nanotriangles
KW  - nanoflowers
KW  - wavelength
Y1  - 2019
U6  - https://doi.org/10.1039/C9RA02384D
SN  - 2046-2069
VL  - 9
SP  - 23633
EP  - 23641
PB  - RSC Publishing
CY  - London
ER  - 
TY  - JOUR
A1  - Kirste, Matthias
A1  - Brietzke, Thomas Martin
A1  - Holdt, Hans-Jürgen
A1  - Schilde, Uwe
T1  - The crystal structure of 1,12-diazaperylene, C₁₈H₁₀N₂
JF  - Zeitschrift für Kristallographie - New Crystal Structures
N2  - C₁₈H₁₀N₂, monoclinic, P2₁/c (no. 14), a=7.9297(9) Å,
b=11.4021(14) Å, c=13.3572(15) Å, β=105.363(8)°,
V =1164.5(2) ų, Z =4, Rgt(F)=0.0325, wRref(F²)=0.0774,
T =210(2) K.
Y1  - 2019
U6  - https://doi.org/10.1515/NCRS-2019-0385
SN  - 2196-7105
SN  - 2194-4946
VL  - 234
IS  - 6
SP  - 1255
EP  - 1257
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Raju, Rajarshi Roy
A1  - Liebig, Ferenc
A1  - Hess, Andreas
A1  - Schlaad, Helmut
A1  - Koetz, Joachim
T1  - Temperature-triggered reversible breakdown of polymer-stabilized olive
BT  - silicone oil Janus emulsions
JF  - RSC Advances
N2  - A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly(N,N-diethylacrylamide) carrying 0.7 mol% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis.
KW  - microgels
KW  - step
Y1  - 2019
U6  - https://doi.org/10.1039/c9ra03463c
SN  - 2046-2069
VL  - 9
IS  - 35
SP  - 19271
EP  - 19277
PB  - RSC Publishing
CY  - London
ER  - 
TY  - JOUR
A1  - Krueger, Tobias
A1  - Kelling, Alexandra
A1  - Linker, Torsten
A1  - Schilde, Uwe
T1  - Crystal structures of three cyclohexane‑based γ‑spirolactams
BT  - determination of configurations and conformations
JF  - BMC Chemistry
N2  - The title compounds, 2-azaspiro[4.5]deca-1-one, C₉H₁₅NO, (1a), cis-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1b), and trans-8-methyl-2-azaspiro[4.5]deca-1-one, C₁₀H₁₇NO, (1c), were synthesized from benzoic acids 2 in only 3 steps in high yields. Crystallization from n-hexane afforded single crystals, suitable for X-ray diffraction. Thus, the configurations, conformations, and interesting crystal packing effects have been determined unequivocally. The bicyclic skeleton consists of a lactam ring, attached by a spiro junction to a cyclohexane ring. The lactam ring adopts an envelope conformation and the cyclohexane ring has a chair conformation. The main difference between compound 1b and compound 1c is the position of the carbonyl group on the 2-pyrrolidine ring with respect to the methyl group on the 8-position of the cyclohexane ring, which is cis (1b) or trans (1c). A remarkable feature of all three compounds is the existence of a mirror plane within the molecule. Given that all compounds crystallize in centrosymmetric space groups, the packing always contains interesting enantiomer-like pairs. Finally, the structures are stabilized by intermolecular N–H···O hydrogen bonds.
KW  - 2-Azaspiro[4.5]deca-1-ones
KW  - Cis- and trans-form
KW  - Configuration
KW  - Conformation
KW  - Lactams
Y1  - 2019
U6  - https://doi.org/10.1186/s13065-019-0586-7
SN  - 2661-801X
VL  - 13
IS  - 69
PB  - Springer International Publishing
CY  - Basel
ER  - 
TY  - JOUR
A1  - Heck, Christian
A1  - Kanehira, Yuya
A1  - Kneipp, Janina
A1  - Bald, Ilko
T1  - Amorphous Carbon Generation as a Photocatalytic Reaction on DNA-Assembled Gold and Silver Nanostructures
JF  - Molecules
N2  - Background signals from in situ-formed amorphous carbon, despite not being fully understood, are known to be a common issue in few-molecule surface-enhanced Raman scattering (SERS). Here, discrete gold and silver nanoparticle aggregates assembled by DNA origami were used to study the conditions for the formation of amorphous carbon during SERS measurements. Gold and silver dimers were exposed to laser light of varied power densities and wavelengths. Amorphous carbon prevalently formed on silver aggregates and at high power densities. Time-resolved measurements enabled us to follow the formation of amorphous carbon. Silver nanolenses consisting of three differently-sized silver nanoparticles were used to follow the generation of amorphous carbon at the single-nanostructure level. This allowed observation of the many sharp peaks that constitute the broad amorphous carbon signal found in ensemble measurements. In conclusion, we highlight strategies to prevent amorphous carbon formation, especially for DNA-assembled SERS substrates.
KW  - amorphous carbon
KW  - DNA origami
KW  - SERS
KW  - nanoparticle dimers
KW  - nanolenses
Y1  - 2019
U6  - https://doi.org/10.3390/molecules24122324
SN  - 1420-3049
VL  - 24
IS  - 12
PB  - MDPI
CY  - Basel
ER  -