2014, Kohrt, C., Spannenberg, A., Werner, T.

In the crystal structure of the title salt, C2H 8NO+·I-, N-H⋯O, N-H⋯I and O-H⋯I hydrogen bonds lead to the formation of layers staggered along the c axis.

2014, Haehnel, M., Spannenberg, A., Rosenthal, U.

The title dinuclear half-sandwich complex, [CpTi(OCH=CH2) (μ2-N-iPr)]2 (Cp = cyclopentadienyl; iPr = isopropyl), was obtained from the reaction of Cp2TiCl2, n-butyllithium and isopropylamine in tetrahydrofuran. Each TiIV atom is coordinated by one Cp ligand, one vinyloxy unit and two bridging imido groups in a strongly distorted tetrahedral geometry. There are two half molecules in the asymmetric unit, such that whole molecules being generated by inversion symmetry.

2020, Mora-Boza, A., Włodarczyk-Biegun, M.K., Del Campo, A., Vázquez-Lasa, B., Román, J.S.

The fabrication of intricate and long-term stable 3D polymeric scaffolds by a 3D printing technique is still a challenge. In the biomedical field, hydrogel materials are very frequently used because of their excellent biocompatibility and biodegradability, however the improvement of their processability and mechanical properties is still required. This paper reports the fabrication of dual crosslinked 3D scaffolds using a low concentrated (<10 wt%) ink of gelatin methacryloyl (GelMA)/chitosan and a novel crosslinking agent, glycerylphytate (G1Phy) to overcome the current limitations in the 3D printing field using hydrogels. The applied methodology consisted of a first ultraviolet light (UV) photopolymerization followed by a post-printing ionic crosslinking treatment with G1Phy. This crosslinker provides a robust framework and avoids the necessity of neutralization with strong bases. The blend ink showed shear-thinning behavior and excellent printability in the form of a straight and homogeneous filament. UV curing was undertaken simultaneously to 3D deposition, which enhanced precision and shape fidelity (resolution ≈150 μm), and prevented the collapse of the subsequent printed layers (up to 28 layers). In the second step, the novel G1Phy ionic crosslinker agent provided swelling and long term stability properties to the 3D scaffolds. The multi-layered printed scaffolds were mechanically stable under physiological conditions for at least one month. Preliminary in vitro assays using L929 fibroblasts showed very promising results in terms of adhesion, spreading, and proliferation in comparison to other phosphate-based traditional crosslinkers (i.e. TPP). We envision that the proposed combination of the blend ink and 3D printing approach can have widespread applications in the regeneration of soft tissues.

2014, Meyer-Ilse, J., Bauroth, S., Bräutigam, M., Schmitt, M., Popp, J., Beckert, R., Rockstroh, N., Pilz, T.D., Monczak, K., Heinemann, F.W., Rau, S., Dietzek, B.

The photophysical properties of Ruthenium-bipyridine complexes bearing a bibenzimidazole ligand were investigated. The nitrogens on the bibenzimidazole-ligand were protected, by adding either a phenylene group or a 1,2-ethandiyl group, to remove the photophysical dependence of the complex on the protonation state of the bibenzimidazole ligand. This protection results in the bibenzimidazole ligand contributing to the MLCT transition, which is experimentally evidenced by (resonance) Raman scattering in concert with DFT calculations for a detailed mode assignment in the (resonance) Raman spectra.

2016, Davies, Heather S., Singh, Prabha, Deckert-Gaudig, Tanja, Deckert, Volker, Rousseau, Karine, Ridley, Caroline E., Dowd, Sarah E., Doig, Andrew J., Pudney, Paul D. A., Thornton, David J., Blanch, Ewan W.

The major structural components of protective mucus hydrogels on mucosal surfaces are the secreted polymeric gel-forming mucins. The very high molecular weight and extensive O-glycosylation of gel-forming mucins, which are key to their viscoelastic properties, create problems when studying mucins using conventional biochemical/structural techniques. Thus, key structural information, such as the secondary structure of the various mucin subdomains, and glycosylation patterns along individual molecules, remains to be elucidated. Here, we utilized Raman spectroscopy, Raman optical activity (ROA), circular dichroism (CD), and tip-enhanced Raman spectroscopy (TERS) to study the structure of the secreted polymeric gel-forming mucin MUC5B. ROA indicated that the protein backbone of MUC5B is dominated by unordered conformation, which was found to originate from the heavily glycosylated central mucin domain by isolation of MUC5B O-glycan-rich regions. In sharp contrast, recombinant proteins of the N-terminal region of MUC5B (D1-D2-D′-D3 domains, NT5B), C-terminal region of MUC5B (D4-B-C-CK domains, CT5B) and the Cys-domain (within the central mucin domain of MUC5B) were found to be dominated by the β-sheet. Using these findings, we employed TERS, which combines the chemical specificity of Raman spectroscopy with the spatial resolution of atomic force microscopy to study the secondary structure along 90 nm of an individual MUC5B molecule. Interestingly, the molecule was found to contain a large amount of α-helix/unordered structures and many signatures of glycosylation, pointing to a highly O-glycosylated region on the mucin.

2018-10-16, Plane, John M. C., Feng, Wuhu, Gómez Martín, Juan Carlos, Gerding, Michael, Raizada, Shikha

Meteoric ablation produces layers of metal atoms in the mesosphere and lower thermosphere (MLT). It has been known for more than 30 years that the Ca atom layer is depleted by over 2 orders of magnitude compared with Na, despite these elements having nearly the same elemental abundance in chondritic meteorites. In contrast, the Ca+ ion abundance is depleted by less than a factor of 10. To explain these observations, a large database of neutral and ion–molecule reaction kinetics of Ca species, measured over the past decade, was incorporated into the Whole Atmosphere Community Climate Model (WACCM). A new meteoric input function for Ca and Na, derived using a chemical ablation model that has been tested experimentally with a Meteoric Ablation Simulator, shows that Ca ablates almost 1 order of magnitude less efficiently than Na. WACCM-Ca simulates the seasonal Ca layer satisfactorily when compared with lidar observations, but tends to overestimate Ca+ measurements made by rocket mass spectrometry and lidar. A key finding is that CaOH and CaCO3 are very stable reservoir species because they are involved in essentially closed reaction cycles with O2 and O. This has been demonstrated experimentally for CaOH, and in this study for CaCO3 using electronic structure and statistical rate theory. Most of the neutral Ca is therefore locked in these reservoirs, enabling rapid loss through polymerization into meteoric smoke particles, and this explains the extreme depletion of Ca.

2015, Beer, Meike V., Hahn, Kathrin, Diederichs, Sylvia, Fabry, Marlies, Singh, Smriti, Spencer, Steve J., Salber, Jochen, Möller, Martin, Shard, Alexander G., Groll, Jürgen

Hydrogels are extensively studied for biomaterials application as they provide water swollen noninteracting matrices in which specific binding motifs and enzyme-sensitive degradation sites can be incorporated to tailor cell adhesion, proliferation, and migration. Hydrogels also serve as excellent basis for surface modification of biomaterials where interfacial characteristics are decisive for implant success or failure. However, the three-dimensional nature of hydrogels makes it hard to distinguish between the bioactive ligand density at the hydrogel-cell interface that is able to interact with cells and the ligands that are immobilized inside the hydrogel and not accessible for cells. Here, the authors compare x-ray photoelectron spectrometry (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), enzyme linked immunosorbent assay (ELISA), and the correlation with quantitative cell adhesion using primary human dermal fibroblasts (HDF) to gain insight into ligand distribution. The authors show that although XPS provides the most useful quantitative analysis, it lacks the sensitivity to measure biologically meaningful concentrations of ligands. However, ToF-SIMS is able to access this range provided that there are clearly distinguishable secondary ions and a calibration method is found. Detection by ELISA appears to be sensitive to the ligand density on the surface that is necessary to mediate cell adhesion, but the upper limit of detection coincides closely with the minimal ligand spacing required to support cell proliferation. Radioactive measurements and ELISAs were performed on amine reactive well plates as true 2D surfaces to estimate the ligand density necessary to allow cell adhesion onto hydrogel films. Optimal ligand spacing for HDF adhesion and proliferation on ultrathin hydrogel films was determined as 6.5 ± 1.5 nm.

2016, Cowcher, David P., Deckert-Gaudig, Tanja, Brewster, Victoria L., Ashton, Lorna, Deckert, Volker, Goodacre, Royston

The correct glycosylation of biopharmaceutical glycoproteins and their formulations is essential for them to have the desired therapeutic effect on the patient. It has recently been shown that Raman spectroscopy can be used to quantify the proportion of glycosylated protein from mixtures of native and glycosylated forms of bovine pancreatic ribonuclease (RNase). Here we show the first steps toward not only the detection of glycosylation status but the characterization of glycans themselves from just a few protein molecules at a time using tip-enhanced Raman scattering (TERS). While this technique generates complex data that are very dependent on the protein orientation, with the careful development of combined data preprocessing, univariate and multivariate analysis techniques, we have shown that we can distinguish between the native and glycosylated forms of RNase. Many glycoproteins contain populations of subtly different glycoforms; therefore, with stricter orientation control, we believe this has the potential to lead to further glycan characterization using TERS, which would have use in biopharmaceutical synthesis and formulation research.

2018, Pretscher, Martin, Pineda-Contreras, Beatriz A., Kaiser, Patrick, Reich, Steffen, Schöbel, Judith, Kuttner, Christian, Freitag, Ruth, Fery, Andreas, Schmalz, Holger, Agarwal, Seema

Smart polymers are a valuable platform to protect and control the activity of biological agents over a wide range of conditions, such as low pH, by proper encapsulation. Such conditions are present in olive oil mill wastewater with phenol as one of the most problematic constituents. We show that elastic and pH-responsive diblock copolymer fibers are a suitable carrier for Corynebacterium glutamicum, i.e., bacteria which are known for their ability to degrade phenol. Free C. glutamicum does not survive low pH conditions and fails to degrade phenol at low pH conditions. Our tea-bag like biohybrid system, where the pH-responsive diblock copolymer acts as a protecting outer shell for the embedded bacteria, allows phenol degradation even at low pH. Utilizing a two-step encapsulation process, planktonic cells were first encapsulated in poly(vinyl alcohol) to protect the bacteria against the organic solvents used in the second step employing coaxial electrospinning.

2019, Rüger J., Mondol A.S., Schie I.W., Popp J., Krafft C.

High-throughput screening Raman spectroscopy (HTS-RS) with automated localization algorithms offers unsurpassed speed and sensitivity to investigate the effect of dithiothreitol on the diatom Phaedactylum tricornutum. The HTS-RS capability that was demonstrated for this model system can be transferred to unmet analytical applications such as kinetic in vivo studies of microalgal assemblages. © 2019 The Royal Society of Chemistry.