TY  - JOUR
A1  - Yuan, Jinkai
A1  - Neri, Wilfrid
A1  - Zakri, Cecile
A1  - Merzeau, Pascal
A1  - Kratz, Karl
A1  - Lendlein, Andreas
A1  - Poulin, Philippe
T1  - Shape memory nanocomposite fibers for untethered high-energy microengines
JF  - Science
N2  - Classic rotating engines are powerful and broadly used but are of complex design and difficult to miniaturize. It has long remained challenging to make large-stroke, high-speed, high-energy microengines that are simple and robust. We show that torsionally stiffened shape memory nanocomposite fibers can be transformed upon insertion of twist to store and provide fast and high-energy rotations. The twisted shape memory nanocomposite fibers combine high torque with large angles of rotation, delivering a gravimetric work capacity that is 60 times higher than that of natural skeletal muscles. The temperature that triggers fiber rotation can be tuned. This temperature memory effect provides an additional advantage over conventional engines by allowing for the tunability of the operation temperature and a stepwise release of stored energy.
Y1  - 2019
U6  - https://doi.org/10.1126/science.aaw3722
SN  - 0036-8075
SN  - 1095-9203
VL  - 365
IS  - 6449
SP  - 155
EP  - 158
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ugwuja, Chidinma G.
A1  - Adelowo, Olawale O.
A1  - Ogunlaja, Aemere
A1  - Omorogie, Martins O.
A1  - Olukanni, Olumide D.
A1  - Ikhimiukor, Odion O.
A1  - Iermak, Ievgeniia
A1  - Kolawole, Gabriel A.
A1  - Günter, Christina
A1  - Taubert, Andreas
A1  - Bodede, Olusola
A1  - Moodley, Roshila
A1  - Inada, Natalia M.
A1  - Camargo, Andrea S.S. de
A1  - Unuabonah, Emmanuel Iyayi
T1  - Visible-Light-Mediated Photodynamic Water Disinfection @ Bimetallic-Doped Hybrid Clay Nanocomposites
JF  - ACS applied materials & interfaces
N2  - This study reports a new class of photocatalytic hybrid clay nanocomposites prepared from low-cost sources (kaolinite clay and Carica papaya seeds) doped with Zn and Cu salts via a solvothermal process. X-ray diffraction analysis suggests that Cu-doping and Cu/Zn-doping introduce new phases into the crystalline structure of Kaolinite clay, which is linked to the reduced band gap of kaolinite from typically between 4.9 and 8.2 eV to 2.69 eV for Cu-doped and 1.5 eV for Cu/Zn hybrid clay nanocomposites (Nisar, J.; Arhammar, C.; Jamstorp, E.; Ahuja, R. Phys. Rev. B 2011, 84, 075120). In the presence of solar light irradiation, Cu- and Cu/Zn-doped nanocomposites facilitate the electron hole pair separation. This promotes the generation of singlet oxygen which in turn improves the water disinfection efficiencies of these novel nanocomposite materials. The nanocomposite materials were further characterized using high-resolution scanning electron microscopy, fluorimetry, therrnogravimetric analysis, and Raman spectroscopy. The breakthrough times of the nanocomposites for a fixed bed mode of disinfection of water contaminated with 2.32 x 10(7) cfu/mL E. coli ATCC 25922 under solar light irradiation are 25 h for Zn-doped, 30 h for Cu-doped, and 35 h for Cu/Zn-doped nanocomposites. In the presence of multidrug and multimetal resistant strains of E. coli, the breakthrough time decreases significantly. Zn-only doped nanocomposites are not photocatalytically active. In the absence of light, the nanocomposites are still effective in decontaminating water, although less efficient than under solar light irradiation. Electrostatic interaction, metal toxicity, and release of singlet oxygen (only in the Cu-doped and Cu/Zn-doped nanocomposites) are the three disinfection mechanisms by which these nanocomposites disinfect water. A regrowth study indicates the absence of any living E. coli cells in treated water even after 4 days. These data and the long hydraulic times (under gravity) exhibited by these nanocomposites during photodisinfection of water indicate an unusually high potential of these nanocomposites as efficient, affordable, and sustainable point-of-use systems for the disinfection of water in developing countries.
KW  - disinfection
KW  - nanocomposite material
KW  - multidrug-resistant Escherichia coli
KW  - water
KW  - reactive oxygen species
Y1  - 2019
U6  - https://doi.org/10.1021/acsami.9b01212
SN  - 1944-8244
SN  - 1944-8252
VL  - 11
IS  - 28
SP  - 25483
EP  - 25494
PB  - American Chemical Society
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Bruun, Kristina
A1  - Hille, Carsten
T1  - Study on intracellular delivery of liposome encapsulated quantum dots using advanced fluorescence microscopy
JF  - Scientific reports
N2  - Quantum dots increasingly gain popularity for in vivo applications. However, their delivery and accumulation into cells can be challenging and there is still lack of detailed information. Thereby, the application of advanced fluorescence techniques can expand the portfolio of useful parameters for a more comprehensive evaluation. Here, we encapsulated hydrophilic quantum dots into liposomes for studying cellular uptake of these so-called lipodots into living cells. First, we investigated photophysical properties of free quantum dots and lipodots observing changes in the fluorescence decay time and translational diffusion behaviour. In comparison to empty liposomes, lipodots exhibited an altered zeta potential, whereas their hydrodynamic size did not change. Fluorescence lifetime imaging microscopy (FLIM) and fluorescence correlation spectroscopy (FCS), both combined with two-photon excitation (2P), were used to investigate the interaction behaviour of lipodots with an insect epithelial tissue. In contrast to the application of free quantum dots, their successful delivery into the cytosol of salivary gland duct cells could be observed when applying lipodots. Lipodots with different lipid compositions and surface charges did not result in considerable differences in the intracellular labelling pattern, luminescence decay time and diffusion behaviour. However, quantum dot degradation after intracellular accumulation could be assumed from reduced luminescence decay times and blue-shifted luminescence signals. In addition to single diffusing quantum dots, possible intracellular clustering of quantum dots could be assumed from increased diffusion times. Thus, by using a simple and manageable liposome carrier system, 2P-FLIM and 2P-FCS recording protocols could be tested, which are promising for investigating the fate of quantum dots during cellular interaction.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-46732-5
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Weis, Philipp
A1  - Hess, Andreas
A1  - Kircher, Gunnar
A1  - Huang, Shilin
A1  - Auernhammer, Günter K.
A1  - Koynov, Kaloian
A1  - Butt, Hans-Jürgen
A1  - Wu, Si
T1  - Effects of Spacers on Photoinduced Reversible Solid-to-Liquid Transitions of Azobenzene-Containing Polymers
JF  - Chemistry - a European journal
N2  - Photoisomerization in some azobenzene-containing polymers (azopolymers) results in reversible solid-to-liquid transitions because trans- and cis-azopolymers have different glass transition temperatures. This property enables photoinduced healing and processing of azopolymers with high spatiotemporal resolution. However, a general lack of knowledge about the influence of the polymer structure on photoinduced reversible solid-to-liquid transitions hinders the design of such novel polymers. Herein, the synthesis and photoresponsive behavior of new azopolymers with different lengths of spacers between the polymer backbone and the azobenzene group on the side chain are reported. Azopolymers with no and 20 methylene spacers did not show photoinduced solid-to-liquid transitions. Azopolymers with 6 or 12 methylene spacers showed photoinduced solid-to-liquid transitions. This study demonstrates that spacers are essential for azopolymers with photoinduced reversible solid-to-liquid transitions, and thus, gives an insight into how to design azopolymers for photoinduced healing and processing.
KW  - azobenzenes
KW  - isomerization
KW  - photochemistry
KW  - polymers
KW  - self-healing
Y1  - 2019
U6  - https://doi.org/10.1002/chem.201902273
SN  - 0947-6539
SN  - 1521-3765
VL  - 25
IS  - 46
SP  - 10946
EP  - 10953
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Qin, Qing
A1  - Zhao, Yun
A1  - Schmallegger, Max
A1  - Heil, Tobias
A1  - Schmidt, Johannes
A1  - Walczak, Ralf
A1  - Gescheidt-Demner, Georg
A1  - Jiao, Haijun
A1  - Oschatz, Martin
T1  - Enhanced Electrocatalytic N-2 Reduction via Partial Anion Substitution in Titanium Oxide-Carbon Composites
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
N2  - The electrochemical conversion of N-2 at ambient conditions using renewably generated electricity is an attractive approach for sustainable ammonia (NH3) production. Considering the chemical inertness of N-2, rational design of efficient and stable catalysts is required. Therefore, in this work, it is demonstrated that a C-doped TiO2/C (C-TixOy/C) material derived from the metal-organic framework (MOF) MIL-125(Ti) can achieve a high Faradaic efficiency (FE) of 17.8 %, which even surpasses most of the established noble metal-based catalysts. On the basis of the experimental results and theoretical calculations, the remarkable properties of the catalysts can be attributed to the doping of carbon atoms into oxygen vacancies (OVs) and the formation of Ti-C bonds in C-TixOy. This binding motive is found to be energetically more favorable for N-2 activation compared to the non-substituted OVs in TiO2. This work elucidates that electrochemical N-2 reduction reaction (NRR) performance can be largely improved by creating catalytically active centers through rational substitution of anions into metal oxides.
KW  - ammonia synthesis
KW  - anion substitution
KW  - MOF-derived catalysts
KW  - N-2 fixation
KW  - non-noble metal catalysts
Y1  - 2019
U6  - https://doi.org/10.1002/anie.201906056
SN  - 1433-7851
SN  - 1521-3773
VL  - 58
IS  - 37
SP  - 13101
EP  - 13106
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Keller, Sebastian
A1  - Wetterhorn, Karl M.
A1  - Vecellio, Alison
A1  - Seeger, Mark
A1  - Rayment, Ivan
A1  - Schubert, Torsten
T1  - Structural and functional analysis of an l-serine O-phosphate decarboxylase involved in norcobamide biosynthesis
JF  - FEBS letters : the journal for rapid publication of short reports in molecular biosciences
N2  - Structural diversity of natural cobamides (Cbas, B12 vitamers) is limited to the nucleotide loop. The loop is connected to the cobalt‐containing corrin ring via an (R)‐1‐aminopropan‐2‐ol O‐2‐phosphate (AP‐P) linker moiety. AP‐P is produced by the l‐threonine O‐3‐phosphate (l‐Thr‐P) decarboxylase CobD. Here, the CobD homolog SMUL_1544 of the organohalide‐respiring epsilonproteobacterium Sulfurospirillum multivorans was characterized as a decarboxylase that produces ethanolamine O‐phosphate (EA‐P) from l‐serine O‐phosphate (l‐Ser‐P). EA‐P is assumed to serve as precursor of the linker moiety of norcobamides that function as cofactors in the respiratory reductive dehalogenase. SMUL_1544 (SmCobD) is a pyridoxal‐5′‐phosphate (PLP)‐containing enzyme. The structural analysis of the SmCobD apoprotein combined with the characterization of truncated mutant proteins uncovered a role of the SmCobD N‐terminus in efficient l‐Ser‐P conversion.
KW  - cobamides
KW  - ethanolamine phosphate
KW  - norcobamide biosynthesis
KW  - serine phosphate decarboxylase
Y1  - 2019
U6  - https://doi.org/10.1002/1873-3468.13543
SN  - 0014-5793
SN  - 1873-3468
VL  - 593
IS  - 21
SP  - 3040
EP  - 3053
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Alrefai, Anas
A1  - Mondal, Suvendu Sekhar
A1  - Wruck, Alexander
A1  - Kelling, Alexandra
A1  - Schilde, Uwe
A1  - Brandt, Philipp
A1  - Janiak, Christoph
A1  - Schoenfeld, Sophie
A1  - Weber, Birgit
A1  - Rybakowski, Lawrence
A1  - Herrman, Carmen
A1  - Brennenstuhl, Katlen
A1  - Eidner, Sascha
A1  - Kumke, Michael Uwe
A1  - Behrens, Karsten
A1  - Günter, Christina
A1  - Müller, Holger
A1  - Holdt, Hans-Jürgen
T1  - Hydrogen-bonded supramolecular metal-imidazolate frameworks: gas sorption, magnetic and UV/Vis spectroscopic properties
JF  - Journal of Inclusion Phenomena and Macrocyclic Chemistry
N2  - By varying reaction parameters for the syntheses of the hydrogen-bonded metal-imidazolate frameworks (HIF) HIF-1 and HIF-2 (featuring 14 Zn and 14 Co atoms, respectively) to increase their yields and crystallinity, we found that HIF-1 is generated in two different frameworks, named as HIF-1a and HIF-1b. HIF-1b is isostructural to HIF-2. We determined the gas sorption and magnetic properties of HIF-2. In comparison to HIF-1a (Brunauer-Emmett-Teller (BET) surface area of 471m(2) g(-1)), HIF-2 possesses overall very low gas sorption uptake capacities [BET(CO2) surface area=85m(2) g(-1)]. Variable temperature magnetic susceptibility measurement of HIF-2 showed antiferromagnetic exchange interactions between the cobalt(II) high-spin centres at lower temperature. Theoretical analysis by density functional theory confirmed this finding. The UV/Vis-reflection spectra of HIF-1 (mixture of HIF-1a and b), HIF-2 and HIF-3 (with 14 Cd atoms) were measured and showed a characteristic absorption band centered at 340nm, which was indicative for differences in the imidazolate framework.
KW  - Gas-sorption
KW  - Ligand design
KW  - Magnetic properties
KW  - Supramolecular chemistry
KW  - Solvothermal synthesis
Y1  - 2019
U6  - https://doi.org/10.1007/s10847-019-00926-6
SN  - 1388-3127
SN  - 1573-1111
VL  - 94
IS  - 3-4
SP  - 155
EP  - 165
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Zhang, Pengfei
A1  - Behl, Marc
A1  - Peng, Xingzhou
A1  - Balk, Maria
A1  - Lendlein, Andreas
T1  - Chemoresponsive Shape-Memory Effect of Rhodium-Phosphine Coordination Polymer Networks
JF  - Chemistry of materials : a publication of the American Chemical Society
N2  - Chemoresponsive polymers are of technological significance for smart sensors or systems capable of molecular recognition. An important key requirement for these applications is the material’s structural integrity after stimulation. We explored whether covalently cross-linked metal ion–phosphine coordination polymers (MPN) can be shaped into any temporary shape and are capable of recovering from this upon chemoresponsive exposure to triphenylphosphine (Ph3P) ligands, whereas the MPN provide structural integrity. Depending on the metal-ion concentration used during synthesis of the MPN, the degree of swelling of the coordination polymer networks could be adjusted. Once the MPN was immersed into Ph3P solution, the reversible ligand-exchange reaction between the metal ions and the free Ph3P in solution causes a decrease of the coordination cross-link density in MPN again. The Ph3P-treated MPN was able to maintain its original shape, indicating a certain stability of shape even after stimulation. In this way, chemoresponsive control of the elastic properties (increase in volume and decrease of mechanical strength) of the MPN was demonstrated. This remarkable behavior motivated us to explore whether the MPN are capable of a chemoresponsive shape-memory effect. In initial experiments, shape fixity of around 60% and shape recovery of almost 90% were achieved when the MPN was exposed to Ph3P in case of rhodium. Potential applications for chemoresponsive shape-memory systems could be shapable semiconductors, e.g., for lighting or catalysts, which provide catalytic activity on demand.
Y1  - 2019
U6  - https://doi.org/10.1021/acs.chemmater.9b00363
SN  - 0897-4756
SN  - 1520-5002
VL  - 31
IS  - 15
SP  - 5402
EP  - 5407
PB  - American Chemical Society
CY  - Washington
ER  - 
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  -