TY - JOUR A1 - Goldhahn, Christian A1 - Schubert, Jonas A1 - Schlaad, Helmut A1 - Ferri, James K. A1 - Fery, Andreas A1 - Chanana, Munish T1 - Synthesis of Metal@Protein@Polymer Nanoparticles with Distinct Interfacial and Phase Transfer Behavior JF - Chemistry of materials : a publication of the American Chemical Society N2 - In this study, we present a novel and facile method for the synthesis of multiresponsive plasmonic nanoparticles with an interesting interfacial behavior. We used thiol-initiated photopolymerization technique to graft poly(N-isopropylacrylamide) onto the surface of protein-coated gold nanoparticles. The combination of the protein bovine serum albumin with the thermoresponsive polymer leads to smart hybrid nanoparticles, which show a stimuli-responsive behavior of their aggregation and a precisely controllable phase transfer behavior. Three interconnected stimuli, namely, temperature, ionic strength, and pH, were identified as property tuning switches. The aggregation was completely reversible and was quantified by determining Smoluchowski’s instability ratios with time-resolved dynamic light scattering. The tunable hydrophobicity via the three stimuli was used to study interfacial activity and phase transfer behavior of the nanoparticles at an octanol/water interface. Depending on the type of coating (i.e., protein or protein/polymer) as well as the three external stimuli, the nanoparticles either remained in the aqueous phase (aggregated or nonaggregated), accumulated at the oil/water interface, wet the glass wall between the glass vial and the octanol phase, or even crossed the oil/water interface. Such smart and interfacially active nanoparticles with external triggers that are capable of crossing oil/water interfaces under physiological conditions open up new avenues for a variety of applications ranging from the development of drug-delivery nanosystems across biological barriers to the preparation of new catalytic materials. Y1 - 2018 U6 - https://doi.org/10.1021/acs.chemmater.8b02314 SN - 0897-4756 SN - 1520-5002 VL - 30 IS - 19 SP - 6717 EP - 6727 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Ehlert, Christopher A1 - Gühr, Markus A1 - Saalfrank, Peter T1 - An efficient first principles method for molecular pump-probe NEXAFS spectra BT - application to thymine and azobenzene JF - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr N2 - Pump-probe near edge X-ray absorption fine structure (PP-NEXAFS) spectra of molecules offer insight into valence-excited states, even if optically dark. In PP-NEXAFS spectroscopy, the molecule is "pumped" by UV or visible light enforcing a valence excitation, followed by an X-ray "probe" exciting core electrons into (now) partially empty valence orbitals. Calculations of PP-NEXAFS have so far been done by costly, correlated wavefunction methods which are not easily applicable to medium-sized or large molecules. Here we propose an efficient, first principles method based on density functional theory in combination with the transition potential and Delta SCF methodology (TP-DFT/Delta SCF) to compute molecular ground state and PP-NEXAFS spectra. We apply the method to n ->pi* pump/O-K-edge NEXAFS probe spectroscopy of thymine (for which both experimental and other theoretical data exist) and to n -> pi* or pi -> pi* pump/N-K-edge NEXAFS probe spectroscopies of trans-and cis-azobenzene. Published by AIP Publishing. Y1 - 2018 U6 - https://doi.org/10.1063/1.5050488 SN - 0021-9606 SN - 1089-7690 VL - 149 IS - 14 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Sun, Zhiyong A1 - Glebe, Ulrich A1 - Charan, Himanshu A1 - Böker, Alexander A1 - Wu, Changzhu T1 - Enzyme-Polymer Conjugates as Robust Pickering Interfacial Biocatalysts for Efficient Biotransformations and One-Pot Cascade Reactions JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition N2 - Despite the rapid development of Pickering interfacial catalysis (PIC) at liquid-liquid interfaces with chemocatalysts, the use of unstable biocatalysts at emulsion interfaces remains a technical challenge. Herein, we present a Pickering interfacial biocatalysis (PIB) platform based on robust and recyclable enzyme-polymer conjugates that act as both catalytic sites and stabilizers at the interface of Pickering emulsions. The conjugates were prepared by growing poly(N-isopropylacrylamide) on a fragile enzyme, benzaldehyde lyase, under physiological conditions. The mild in situ conjugation process preserved the enzyme structure, and the conjugates were used to emulsify a water-organic two-phase system into a stable Pickering emulsion, leading to a significantly larger interfacial area and a 270-fold improvement in catalytic performance as compared to the unemulsified two-phase system. The PIB system could be reused multiple times. Conjugates of other enzymes were also fabricated and applied for cascade reactions. KW - biphasic catalysis KW - cascade reactions KW - enzyme catalysis KW - enzyme-polymer conjugates KW - Pickering interfacial catalysis Y1 - 2018 U6 - https://doi.org/10.1002/anie.201806049 SN - 1433-7851 SN - 1521-3773 VL - 57 IS - 42 SP - 13810 EP - 13814 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Turrini, Nikolaus G. A1 - Kroepfl, Nina A1 - Jensen, Kenneth Bendix A1 - Reiter, Tamara C. A1 - Francesconi, Kevin A. A1 - Schwerdtle, Tanja A1 - Kroutil, Wolfgang A1 - Kuehnelt, Doris T1 - Biosynthesis and isolation of selenoneine from genetically modified fission yeast JF - Metallomics : integrated biometal science N2 - Selenoneine, a naturally occurring form of selenium, is the selenium analogue of ergothioneine, a sulfur species with health relevance not only as a purported antioxidant but likely also beyond. Selenoneine has been speculated to exhibit similar effects. To study selenoneine's health properties as well as its metabolic transformation, the pure compound is required. Chemical synthesis of selenoneine, however, is challenging and biosynthetic approaches have been sought. We herein report the biosynthesis and isolation of selenoneine from genetically modified fission yeast Schizosaccharomyces pombe grown in a medium containing sodium selenate. After cell lysis and extraction with methanol, selenoneine was purified by three consecutive preparative reversed-phase HPLC steps. The product obtained at the mg level was characterised by high resolution mass spectrometry, NMR and HPLC/ICPMS. Biosynthesis was found to be a promising alternative to chemical synthesis, and should be suitable for upscaling to produce higher amounts of this important selenium species in the future. Y1 - 2018 U6 - https://doi.org/10.1039/c8mt00200b SN - 1756-5901 SN - 1756-591X VL - 10 IS - 10 SP - 1532 EP - 1538 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Tadjoung Waffo, Armel Franklin A1 - Yesildag, Cigdem A1 - Caserta, Giorgio A1 - Katz, Sagie A1 - Zebger, Ingo A1 - Lensen, Marga C. A1 - Wollenberger, Ulla A1 - Scheller, Frieder W. A1 - Altintas, Zeynep T1 - Fully electrochemical MIP sensor for artemisinin JF - Sensors and actuators : B, Chemical N2 - This study aims to develop a rapid, sensitive and cost-effective biomimetic electrochemical sensor for artemisinin determination in plant extracts and for pharmacokinetic studies. A novel molecularly imprinted polymer (MIP)based electrochemical sensor was developed by electropolymerization of o-phenylenediamine (o-PD) in the presence of artemisinin on gold wire surface for sensitive detection of artemisinin. The experimental parameters, including selection of functional monomer, polymerization conditions, template extraction after polymerization, influence of pH and buffer were all optimized. Every step of imprinted film synthesis were evaluated by employing voltammetry techniques, surface-enhanced infrared absorption spectroscopy (SEIRAS) and atomic force microscopy (AFM). The specificity was further evaluated by investigating non-specific artemisinin binding on non-imprinted polymer (NIP) surfaces and an imprinting factor of 6.8 was achieved. The artemisinin imprinted polymers using o-PD as functional monomer have provided highly stable and effective binding cavities for artemisinin. Cross-reactivity studies with drug molecules showed that the MIPs are highly specific for artemisinin. The influence of matrix effect was further investigated both in artificial plant matrix and diluted human serum. The results revealed a high affinity of artemisinin-MIP with dissociation constant of 7.3 x 10(-9) M and with a detection limit of 0.01 mu M and 0.02 mu M in buffer and plant matrix, respectively. KW - Electro-synthesized molecularly imprinted polymer KW - o-Phenylenediamine KW - Artemisinin KW - Antimalarial drug detection KW - Electrochemical sensor Y1 - 2018 U6 - https://doi.org/10.1016/j.snb.2018.08.018 SN - 0925-4005 VL - 275 SP - 163 EP - 173 PB - Elsevier CY - Lausanne ER - TY - JOUR A1 - Büchner, Dörthe A1 - John, Leonard A1 - Mertens, Monique A1 - Wessig, Pablo T1 - Detection of dsDNA with [1,3]Dioxolo[4,5-f]benzodioxol (DBD) Dyes JF - Chemistry - a European journal N2 - DBD fluorescent dyes have proven to be useful in numerous applications. To widen the range of biological applications, we propose three different types of DBD molecules that have been modified in such a way that DNA interaction becomes probable. After the successful synthesis of all three compounds, we tested their fluorescent properties and their DNA binding abilities. Two of the three probes exhibit an interaction with dsDNA with subsequent fluorescence enhancement. The determined binding constants of the two new DNA dyes are comparable to other minorgroove-binding dyes. Their large Stokes shifts and their long fluorescent lifetimes are outstanding features of these dyes. KW - DNA recognition KW - dyes/pigments KW - fluorescent probes KW - heterocycles KW - scatchard plot Y1 - 2018 U6 - https://doi.org/10.1002/chem.201804057 SN - 0947-6539 SN - 1521-3765 VL - 24 IS - 60 SP - 16183 EP - 16190 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Schulz, Eike C. A1 - Mehrabi, Pedram A1 - Müller-Werkmeister, Henrike A1 - Tellkamp, Friedjof A1 - Jha, Ajay A1 - Stuart, William A1 - Persch, Elke A1 - De Gasparo, Raoul A1 - Diederich, François A1 - Pai, Emil F. A1 - Miller, R. J. Dwayne T1 - The hit-and-return system enables efficient time-resolved serial synchrotron crystallography JF - Nature methods : techniques for life scientists and chemists N2 - We present a ‘hit-and-return’ (HARE) method for time-resolved serial synchrotron crystallography with time resolution from milliseconds to seconds or longer. Timing delays are set mechanically, using the regular pattern in fixed-target crystallography chips and a translation stage system. Optical pump-probe experiments to capture intermediate structures of fluoroacetate dehalogenase binding to its ligand demonstrated that data can be collected at short (30 ms), medium (752 ms) and long (2,052 ms) intervals. KW - Biophysical chemistry KW - Enzymes KW - Molecular biophysics KW - X-ray crystallography Y1 - 2018 U6 - https://doi.org/10.1038/s41592-018-0180-2 SN - 1548-7091 SN - 1548-7105 VL - 15 IS - 11 SP - 901 EP - 904 PB - Nature Publishing Group (London) CY - London ER - TY - JOUR A1 - Riemer, Nastja A1 - Coswig, Christin A1 - Shipman, Michael A1 - Schmidt, Bernd T1 - Palladium-catalyzed cross-coupling of arenediazonium salts with organoindium or organobismuth reagents JF - Synlett : accounts and rapid communications in synthetic organic chemistry N2 - Arylindium and isolated triarylbismuth compounds generated in situ react as nucleophiles with arenediazonium salts in palladium-catalyzed cross-coupling reactions to give substituted biphenyls. KW - Palladium-catalyzed cross-coupling of arenediazonium salts with organoindium or organobismuth reagents Y1 - 2018 U6 - https://doi.org/10.1055/s-0037-1611001 SN - 0936-5214 SN - 1437-2096 VL - 29 IS - 18 SP - 2427 EP - 2431 PB - Georg Thieme Verlag KG CY - Stuttgart ER - TY - JOUR A1 - Hardy, John G. A1 - Bertin, Annabelle A1 - Torres-Rendon, Jose Guillermo A1 - Leal-Egana, Aldo A1 - Humenik, Martin A1 - Bauer, Felix A1 - Walther, Andreas A1 - Cölfen, Helmut A1 - Schlaad, Helmut A1 - Scheibel, Thomas R. T1 - Facile photochemical modification of silk protein-based biomaterials JF - Macromolecular bioscience N2 - Silk protein-based materials show promise for application as biomaterials for tissue engineering. The simple and rapid photochemical modification of silk protein-based materials composed of either Bombyx mori silkworm silk or engineered spider silk proteins (eADF4(C16)) is reported. Radicals formed on the silk-based materials initiate the polymerization of monomers (acrylic acid, methacrylic acid, or allylamine) which functionalize the surface of the silk materials with poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), or poly(allylamine) (PAAm). To demonstrate potential applications of this type of modification, the polymer-modified silks are mineralized. The PAA- and PMAA-functionalized silks are mineralized with calcium carbonate, whereas the PAAm-functionalized silks are mineralized with silica, both of which provide a coating on the materials that may be useful for bone tissue engineering, which will be the subject of future investigations. KW - biomaterials KW - chemical modification KW - photochemistry KW - silkworm silk KW - spider silk Y1 - 2018 U6 - https://doi.org/10.1002/mabi.201800216 SN - 1616-5187 SN - 1616-5195 VL - 18 IS - 11 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zheng, Botuo A1 - Bai, Tianwen A1 - Tao, Xinfeng A1 - Schlaad, Helmut A1 - Ling, Jun T1 - Identifying the Hydrolysis of Carbonyl Sulfide as a Side Reaction Impeding the Polymerization of N-Substituted Glycine N-Thiocarboxyanhydride JF - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences N2 - Polypeptoids are noticeable biological materials due to their versatile properties and various applications in drug delivery, surface modification, self-assembly, etc. N-Substituted glycine N-thiocarboxyanhydrides (NNTAs) are more stable monomers than the corresponding N-carboxyanhydrides (NNCAs) and enable one to prepare polypeptoids via ring-opening polymerization even in the presence of water. However, larger amounts of water (>10,000 ppm) cause inhibition of the polymerization. Herein, we discover that during polymerization hydrogen sulfide evolves from the hydrolysis of carbonyl sulfide, which is the byproduct of ring-opening reaction, and reacts with NNTA to produce cyclic oligopeptoids. The capture of N-ethylethanethioic acid as an intermediate product confirms the reaction mechanism together with density functional theory quantum computational results. By bubbling the polymerization solution with argon, the side reaction can be suppressed to allow the synthesis of polysarcosine with high molar mass (M-n = 11,200 g/mol, D = 1.25) even in the presence of similar to 10,000 ppm of water. Y1 - 2018 U6 - https://doi.org/10.1021/acs.biomac.8b01119 SN - 1525-7797 SN - 1526-4602 VL - 19 IS - 11 SP - 4263 EP - 4269 PB - American Chemical Society CY - Washington ER -