TY - JOUR
AU - Müller, Hendrik
AU - Weinberger, Christian
AU - Grundmeier, Guido
AU - de los Arcos de Pedro, Maria Teresa
ID - 46480
JF - Journal of Electron Spectroscopy and Related Phenomena
KW - Physical and Theoretical Chemistry
KW - Spectroscopy
KW - Condensed Matter Physics
KW - Atomic and Molecular Physics
KW - and Optics
KW - Radiation
KW - Electronic
KW - Optical and Magnetic Materials
SN - 0368-2048
TI - UV-enhanced environmental charge compensation in near ambient pressure XPS
VL - 264
ER -
TY - JOUR
AB - The influence of nanoscale surface topography on protein adsorption is highly important for numerous applications in medicine and technology. Herein, ferritin adsorption at flat and nanofaceted, single-crystalline Al2O3 surfaces is investigated using atomic force microscopy and X-ray photoelectron spectroscopy. The nanofaceted surfaces are generated by the thermal annealing of Al2O3 wafers at temperatures above 1000 °C, which leads to the formation of faceted saw-tooth-like surface topographies with periodicities of about 160 nm and amplitudes of about 15 nm. Ferritin adsorption at these nanofaceted surfaces is notably suppressed compared to the flat surface at a concentration of 10 mg/mL, which is attributed to lower adsorption affinities of the newly formed facets. Consequently, adsorption is restricted mostly to the pattern grooves, where the proteins can maximize their contact area with the surface. However, this effect depends on the protein concentration, with an inverse trend being observed at 30 mg/mL. Furthermore, different ferritin adsorption behavior is observed at topographically similar nanofacet patterns fabricated at different annealing temperatures and attributed to different step and kink densities. These results demonstrate that while protein adsorption at solid surfaces can be notably affected by nanofacet patterns, fine-tuning protein adsorption in this way requires the precise control of facet properties.
AU - Pothineni, Bhanu K.
AU - Kollmann, Sabrina
AU - Li, Xinyang
AU - Grundmeier, Guido
AU - Erb, Denise J.
AU - Keller, Adrian
ID - 46543
IS - 16
JF - International Journal of Molecular Sciences
KW - Inorganic Chemistry
KW - Organic Chemistry
KW - Physical and Theoretical Chemistry
KW - Computer Science Applications
KW - Spectroscopy
KW - Molecular Biology
KW - General Medicine
KW - Catalysis
SN - 1422-0067
TI - Adsorption of Ferritin at Nanofaceted Al2O3 Surfaces
VL - 24
ER -
TY - JOUR
AB - Covalent peptidomimetic protease inhibitors have gained a lot of attention in drug development in recent years. They are designed to covalently bind the catalytically active amino acids through electrophilic groups called warheads. Covalent inhibition has an advantage in terms of pharmacodynamic properties but can also bear toxicity risks due to non-selective off-target protein binding. Therefore, the right combination of a reactive warhead with a well-suited peptidomimetic sequence is of great importance. Herein, the selectivities of well-known warheads combined with peptidomimetic sequences suited for five different proteases were investigated, highlighting the impact of both structure parts (warhead and peptidomimetic sequence) for affinity and selectivity. Molecular docking gave insights into the predicted binding modes of the inhibitors inside the binding pockets of the different enzymes. Moreover, the warheads were investigated by NMR and LC-MS reactivity assays against serine/threonine and cysteine nucleophile models, as well as by quantum mechanics simulations.
AU - Müller, Patrick
AU - Meta, Mergim
AU - Meidner, Jan Laurenz
AU - Schwickert, Marvin
AU - Meyr, Jessica
AU - Schwickert, Kevin
AU - Kersten, Christian
AU - Zimmer, Collin
AU - Hammerschmidt, Stefan Josef
AU - Frey, Ariane
AU - Lahu, Albin
AU - de la Hoz-Rodríguez, Sergio
AU - Agost-Beltrán, Laura
AU - Rodríguez, Santiago
AU - Diemer, Kira
AU - Neumann, Wilhelm
AU - Gonzàlez, Florenci V.
AU - Engels, Bernd
AU - Schirmeister, Tanja
ID - 50150
IS - 8
JF - International Journal of Molecular Sciences
KW - Inorganic Chemistry
KW - Organic Chemistry
KW - Physical and Theoretical Chemistry
KW - Computer Science Applications
KW - Spectroscopy
KW - Molecular Biology
KW - General Medicine
KW - Catalysis
SN - 1422-0067
TI - Investigation of the Compatibility between Warheads and Peptidomimetic Sequences of Protease Inhibitors—A Comprehensive Reactivity and Selectivity Study
VL - 24
ER -
TY - JOUR
AB - DNA origami technology enables the folding of DNA strands into complex nanoscale shapes whose properties and interactions with molecular species often deviate significantly from that of genomic DNA. Here, we investigate the salting-out of different DNA origami shapes by the kosmotropic salt ammonium sulfate that is routinely employed in protein precipitation. We find that centrifugation in the presence of 3 M ammonium sulfate results in notable precipitation of DNA origami nanostructures but not of double-stranded genomic DNA. The precipitated DNA origami nanostructures can be resuspended in ammonium sulfate-free buffer without apparent formation of aggregates or loss of structural integrity. Even though quasi-1D six-helix bundle DNA origami are slightly less susceptible toward salting-out than more compact DNA origami triangles and 24-helix bundles, precipitation and recovery yields appear to be mostly independent of DNA origami shape and superstructure. Exploiting the specificity of ammonium sulfate salting-out for DNA origami nanostructures, we further apply this method to separate DNA origami triangles from genomic DNA fragments in a complex mixture. Our results thus demonstrate the possibility of concentrating and purifying DNA origami nanostructures by ammonium sulfate-induced salting-out.
AU - Hanke, Marcel
AU - Hansen, Niklas
AU - Chen, Ruiping
AU - Grundmeier, Guido
AU - Fahmy, Karim
AU - Keller, Adrian
ID - 30209
IS - 5
JF - International Journal of Molecular Sciences
KW - Inorganic Chemistry
KW - Organic Chemistry
KW - Physical and Theoretical Chemistry
KW - Computer Science Applications
KW - Spectroscopy
KW - Molecular Biology
KW - General Medicine
KW - Catalysis
SN - 1422-0067
TI - Salting-Out of DNA Origami Nanostructures by Ammonium Sulfate
VL - 23
ER -
TY - JOUR
AU - Yang, Yu
AU - Huang, Jingyuan
AU - Dornbusch, Daniel
AU - Grundmeier, Guido
AU - Fahmy, Karim
AU - Keller, Adrian
AU - Cheung, David L.
ID - 32432
JF - Langmuir
KW - Electrochemistry
KW - Spectroscopy
KW - Surfaces and Interfaces
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0743-7463
TI - Effect of Surface Hydrophobicity on the Adsorption of a Pilus-Derived Adhesin-like Peptide
VL - 38
ER -
TY - JOUR
AB - Guanidinium (Gdm) undergoes interactions with both hydrophilic and hydrophobic groups and, thus, is a highly potent denaturant of biomolecular structure. However, our molecular understanding of the interaction of Gdm with proteins and DNA is still rather limited. Here, we investigated the denaturation of DNA origami nanostructures by three Gdm salts, i.e., guanidinium chloride (GdmCl), guanidinium sulfate (Gdm2SO4), and guanidinium thiocyanate (GdmSCN), at different temperatures and in dependence of incubation time. Using DNA origami nanostructures as sensors that translate small molecular transitions into nanostructural changes, the denaturing effects of the Gdm salts were directly visualized by atomic force microscopy. GdmSCN was the most potent DNA denaturant, which caused complete DNA origami denaturation at 50 °C already at a concentration of 2 M. Under such harsh conditions, denaturation occurred within the first 15 min of Gdm exposure, whereas much slower kinetics were observed for the more weakly denaturing salt Gdm2SO4 at 25 °C. Lastly, we observed a novel non-monotonous temperature dependence of DNA origami denaturation in Gdm2SO4 with the fraction of intact nanostructures having an intermediate minimum at about 40 °C. Our results, thus, provide further insights into the highly complex Gdm–DNA interaction and underscore the importance of the counteranion species.
AU - Hanke, Marcel
AU - Hansen, Niklas
AU - Tomm, Emilia
AU - Grundmeier, Guido
AU - Keller, Adrian
ID - 32589
IS - 15
JF - International Journal of Molecular Sciences
KW - Inorganic Chemistry
KW - Organic Chemistry
KW - Physical and Theoretical Chemistry
KW - Computer Science Applications
KW - Spectroscopy
KW - Molecular Biology
KW - General Medicine
KW - Catalysis
SN - 1422-0067
TI - Time-Dependent DNA Origami Denaturation by Guanidinium Chloride, Guanidinium Sulfate, and Guanidinium Thiocyanate
VL - 23
ER -
TY - JOUR
AB - A two-step seeded-growth method was refined to synthesize Au@Pd core@shell nanoparticles with thin Pd shells, which were then deposited onto alumina to obtain a supported Au@Pd/Al2O3 catalyst active for prototypical CO oxidation. By the strict control of temperature and Pd/Au molar ratio and the use of l-ascorbic acid for making both Au cores and Pd shells, a 1.5 nm Pd layer is formed around the Au core, as evidenced by transmission electron microscopy and energy-dispersive spectroscopy. The core@shell structure and the Pd shell remain intact upon deposition onto alumina and after being used for CO oxidation, as revealed by additional X-ray diffraction and X-ray photoemission spectroscopy before and after the reaction. The Pd shell surface was characterized with in situ infrared (IR) spectroscopy using CO as a chemical probe during CO adsorption–desorption. The IR bands for CO ad-species on the Pd shell suggest that the shell exposes mostly low-index surfaces, likely Pd(111) as the majority facet. Generally, the IR bands are blue-shifted as compared to conventional Pd/alumina catalysts, which may be due to the different support materials for Pd, Au versus Al2O3, and/or less strain of the Pd shell. Frequencies obtained from density functional calculations suggest the latter to be significant. Further, the catalytic CO oxidation ignition-extinction processes were followed by in situ IR, which shows the common CO poisoning and kinetic behavior associated with competitive adsorption of CO and O2 that is typically observed for noble metal catalysts.
AU - Feng, Yanyue
AU - Schaefer, Andreas
AU - Hellman, Anders
AU - Di, Mengqiao
AU - Härelind, Hanna
AU - Bauer, Matthias
AU - Carlsson, Per-Anders
ID - 40984
IS - 42
JF - Langmuir
KW - Electrochemistry
KW - Spectroscopy
KW - Surfaces and Interfaces
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0743-7463
TI - Synthesis and Characterization of Catalytically Active Au Core─Pd Shell Nanoparticles Supported on Alumina
VL - 38
ER -
TY - JOUR
AB - Currently, chemistry and physics are strongly dependent on the concept of the oxidation state. While the formal oxidation state is easily evaluated, the real physical oxidation state value is often difficult to determine and significantly varies from the formal values. Determination of the ionization threshold in X-ray absorption spectroscopy (XANES) relies on the absorption edge position and sometimes poses limitations, mainly due to the edge resonances. Moreover, the lower energy states can be probed only within x-soft or XUV photons providing only surface state information of probed materials. Here, we employ high energy resolution off-resonant spectroscopy to determine both 1s and 3p binding energies of Fe-based materials and therefore correlate to their physical oxidation state. The results are compared to the ones obtained with classical X-ray absorption, X-ray emission, and photoelectron spectroscopies. The observed differences in binding energies are discussed in a frame of initial and final state interactions with the atom's electronic configurations. The presented methodology is discussed towards potential use to single-shot experiments and application at X-ray free-electron lasers. Alternatively, core level X-ray emission spectroscopy can be used, but the emission line positions are strongly affected by spin-orbit interaction. However, due to the energy transfer from the photon to the excited core electron, the same information as in XANES is probed in high energy resolution off-resonant spectroscopy (HEROS). Based on the Kramers–Heisenberg theory, we propose a new approach for ionization threshold determination which is free of the limitations encountered in XANES-based determination of the core state energy. Namely, the value of core state energy can be determined analytically using a few HEROS spectra recorded with significantly higher spectral resolution. This approach provides a basis for the universal physical oxidation state determination method.
AU - Nowakowski, Michal
AU - Kalinko, Aleksandr
AU - Szlachetko, Jakub
AU - Fanselow, Rafał
AU - Bauer, Matthias
ID - 40986
IS - 11
JF - Journal of Analytical Atomic Spectrometry
KW - Spectroscopy
KW - Analytical Chemistry
SN - 0267-9477
TI - High resolution off resonant spectroscopy as a probe of the oxidation state
VL - 37
ER -
TY - JOUR
AB - The direct conversion between HEROS-XES and XANES edge position (E0) without need of measuring absorption spectra.
AU - Nowakowski, Michal
AU - Kalinko, Aleksandr
AU - Szlachetko, Jakub
AU - Fanselow, Rafał
AU - Bauer, Matthias
ID - 41319
IS - 11
JF - Journal of Analytical Atomic Spectrometry
KW - Spectroscopy
KW - Analytical Chemistry
SN - 0267-9477
TI - High resolution off resonant spectroscopy as a probe of the oxidation state
VL - 37
ER -
TY - JOUR
AU - Knust, Steffen
AU - Ruhm, Lukas
AU - Kuhlmann, Andreas
AU - Meinderink, Dennis
AU - Bürger, Julius
AU - Lindner, Jörg
AU - de los Arcos de Pedro, Maria Teresa
AU - Grundmeier, Guido
ID - 34087
IS - 7
JF - Journal of Raman Spectroscopy
KW - Spectroscopy
KW - General Materials Science
SN - 0377-0486
TI - In situ backside Raman spectroscopy of zinc oxide nanorods in an atmospheric‐pressure dielectric barrier discharge plasma
VL - 52
ER -
TY - JOUR
AB - Individual grains of chalcopyrite solar cell absorbers can facet in different crystallographic directions at their surfaces. To gain a deeper understanding of the junction formation in these devices, we correlate variations in the surface facet orientation with the defect electronic properties. We use a combined analytical approach based on scanning tunneling spectroscopy (STS), scanning electron microscopy, and electron back scatter diffraction (EBSD), where we perform these experiments on identical surface areas as small as 2 × 2 µm2 with a lateral resolution well below 50 nm. The topography of the absorber surfaces indicates two main morphological features: micro-faceted, long basalt-like columns and their short nano-faceted terminations. Our STS results reveal that the long columns exhibit spectral signatures typical for the presence of pronounced oxidation-induced surface dipoles in conjunction with an increased density of electronic defect levels. In contrast, the nano-faceted terminations of the basalt-like columns are largely passivated in terms of electronic defect levels within the band gap region. Corresponding crystallographic data based on EBSD experiments show that the surface of the basalt-like columns can be assigned to intrinsically polar facet orientations, while the passivated terminations are assigned to non-polar planes. Ab-initio calculations suggest that the polar surfaces are more prone to oxidation and resulting O-induced defects, in comparison to non-polar planes. Our results emphasize the correlation between morphology, surface facet orientations and surface electronic properties. Furthermore, this work aids in gaining a fundamental understanding of oxidation induced lateral inhomogeneities in view of the p-n junction formation in chalcopyrite thin-film solar cells.
AU - Elizabeth, Amala
AU - Conradi, Hauke
AU - K. Sahoo, Sudhir
AU - Kodalle, Tim
AU - A. Kaufmann, Christian
AU - Kühne, Thomas
AU - Mirhosseini, Hossein
AU - Abou-Ras, Daniel
AU - Mönig, Harry
ID - 19823
JF - Acta Materialia
KW - Chalcopyrite absorber
KW - Scanning tunneling spectroscopy
KW - Electron backscatter diffraction
KW - Density functional theory
KW - Surface dipole
SN - 1359-6454
TI - Correlating facet orientation, defect-level density and dipole layer formation at the surface of polycrystalline CuInSe2 thin films
VL - 200
ER -
TY - JOUR
AU - Gujt, Jure
AU - Zimmer, Peter
AU - Zysk, Frederik
AU - Süß, Vicky
AU - Felser, Claudia
AU - Bauer, Matthias
AU - Kühne, Thomas
ID - 41024
IS - 3
JF - Structural Dynamics
KW - Spectroscopy
KW - Condensed Matter Physics
KW - Instrumentation
KW - Radiation
SN - 2329-7778
TI - Water structure near the surface of Weyl semimetals as catalysts in photocatalytic proton reduction
VL - 7
ER -
TY - JOUR
AB -
A gas sensor comprising of a planar electrode device covered with a thin layer of gel polymer electrolyte gave accurate and fast sensing responses for oxygen and ammonia detection in both the cathodic and anodic potential regions.
AU - Lee, Junqiao
AU - Hussain, Ghulam
AU - Lopez Salas, Nieves
AU - MacFarlane, Douglas R.
AU - Silvester, Debbie S.
ID - 40580
IS - 5
JF - The Analyst
KW - Electrochemistry
KW - Spectroscopy
KW - Environmental Chemistry
KW - Biochemistry
KW - Analytical Chemistry
SN - 0003-2654
TI - Thin films of poly(vinylidene fluoride-co-hexafluoropropylene)-ionic liquid mixtures as amperometric gas sensing materials for oxygen and ammonia
VL - 145
ER -
TY - JOUR
AU - Carl, Nico
AU - Müller, Wenke
AU - Schweins, Ralf
AU - Huber, Klaus
ID - 41822
IS - 1
JF - Langmuir
KW - Electrochemistry
KW - Spectroscopy
KW - Surfaces and Interfaces
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0743-7463
TI - Controlling Self-Assembly with Light and Temperature
VL - 36
ER -
TY - JOUR
AU - Hämisch, Benjamin
AU - Büngeler, Anne
AU - Kielar, Charlotte
AU - Keller, Adrian
AU - Strube, Oliver
AU - Huber, Klaus
ID - 41828
IS - 37
JF - Langmuir
KW - Electrochemistry
KW - Spectroscopy
KW - Surfaces and Interfaces
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0743-7463
TI - Self-Assembly of Fibrinogen in Aqueous, Thrombin-Free Solutions of Variable Ionic Strengths
VL - 35
ER -
TY - JOUR
AU - Stolzenburg, Pierre
AU - Hämisch, Benjamin
AU - Richter, Sebastian
AU - Huber, Klaus
AU - Garnweitner, Georg
ID - 41830
IS - 43
JF - Langmuir
KW - Electrochemistry
KW - Spectroscopy
KW - Surfaces and Interfaces
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0743-7463
TI - Secondary Particle Formation during the Nonaqueous Synthesis of Metal Oxide Nanocrystals
VL - 34
ER -
TY - JOUR
AB - Transient changes of the optical response of WS2 monolayers are studied by femtosecond broadband pump–probe spectroscopy. Time-dependent absorption spectra are analyzed by tracking the line width broadening, bleaching, and energy shift of the main exciton resonance as a function of time delay after the excitation. Two main sources for the pump-induced changes of the optical response are identified. Specifically, we find an interplay between modifications induced by many-body interactions from photoexcited carriers and by the subsequent transfer of the excitation to the phonon system followed by cooling of the material through the heat transfer to the substrate.
AU - Ruppert, Claudia
AU - Chernikov, Alexey
AU - Hill, Heather M.
AU - Rigosi, Albert F.
AU - Heinz, Tony F.
ID - 6542
IS - 2
JF - Nano Letters
KW - Atomically thin 2D materials
KW - carrier and phonon dynamics
KW - ultrafast spectroscopy
SN - 1530-6984
TI - The Role of Electronic and Phononic Excitation in the Optical Response of Monolayer WS2 after Ultrafast Excitation
VL - 17
ER -
TY - JOUR
AU - Kley, M.
AU - Kempter, A.
AU - Boyko, V.
AU - Huber, Klaus
ID - 41836
IS - 24
JF - Langmuir
KW - Electrochemistry
KW - Spectroscopy
KW - Surfaces and Interfaces
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0743-7463
TI - Silica Polymerization from Supersaturated Dilute Aqueous Solutions in the Presence of Alkaline Earth Salts
VL - 33
ER -
TY - JOUR
AU - Büngeler, Anne
AU - Hämisch, Benjamin
AU - Huber, Klaus
AU - Bremser, Wolfgang
AU - Strube, Oliver I.
ID - 41835
IS - 27
JF - Langmuir
KW - Electrochemistry
KW - Spectroscopy
KW - Surfaces and Interfaces
KW - Condensed Matter Physics
KW - General Materials Science
SN - 0743-7463
TI - Insight into the Final Step of the Supramolecular Buildup of Eumelanin
VL - 33
ER -
TY - JOUR
AB - Cubic gallium nitride (GaN) films are analyzed with highresolution X-ray diffraction (HRXRD) and Raman spectroscopy. Several cubic GaN layers were grown on 3C-SiC (001) substrate by radio-frequency plasma-assisted molecular beam epitaxy. The layer thickness of the cubic GaN was varied between 75 and 505 nm. The HRXRD analysis reveals a reduction of the full-width at half-maximum (FWHM) of omega scans for growing layer thicknesses, which is caused by a partial compensation of defects. The Raman characterization confirms well-formed c-GaN layers. A more detailed examination of the longitudinal optical mode hints at a correlation of the FWHM of the Raman mode with the dislocation density, which shows the possibility to determine dislocation densities by Ramanspectroscopy on a micrometer scale, which is not possible by HRXRD. Furthermore, this Raman analysis shows that normalized Raman spectra present an alternative way to determine layer thicknesses of thin GaN films.
AU - Rüsing, Michael
AU - Wecker, T.
AU - Berth, Gerhard
AU - As, Donat Josef
AU - Zrenner, Artur
ID - 4240
IS - 4
JF - physica status solidi (b)
KW - cubic gallium nitride
KW - dislocation density
KW - HRXRD
KW - Raman spectroscopy
SN - 0370-1972
TI - Joint Raman spectroscopy and HRXRD investigation of cubic gallium nitride layers grown on 3C-SiC
VL - 253
ER -