Design,Synthesis, and Application of Stimulus‐Sensing Biohybrid Hydrogels

A key feature of any living system is the ability to sense and react to the environmental stimuli. The biochemical characterization of the underlying biological sensors combined with advances in polymer chemistry has enabled the development of stimulus‐sensitive biohybrid materials that translate most diverse chemical and biological input into a precise change in material properties. In this review article, we first describe synthesis strategies of how biological and chemical polymers can functionally be interconnected. We then provide a comprehensive overview of how the different properties of biological sensor molecules such as competitive target binding and allosteric modulation can be harnessed to develop responsive materials with applications in tissue engineering and drug delivery.

     

High-pressure Raman study of SnGeS3

Abstract

We report Raman-scattering studies of SnGeS₃ under hydrostatic pressures up to 19.5 GPa. An assignment to internal-external modes is proposed, based on the pressure slopes obtained. Our data show evidence for two critical pressures, one around 7 GPa and a second one around 12 GPa. The material renders itself Raman inactive at 19.5 GPa. The observed changes are reversible upon pressure release.     

A promotor polymorphism in the Interleukin 11 gene is associated with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a multifactorial disorder characterized by irreversible airflow obstruction due to chronic inflammation. Hence, the gene encoding the anti-inflammatory cytokine IL 11 is a good candidate for being involved in the genetic predisposition to COPD. In order to evaluate the role of the Interleukin 11 (IL 11) gene in the genetic predisposition for COPD, a dinucleotide microsatellite polymorphism in the promoter region has been genotyped in 153 patients with COPD (including 25 non-smokers) and 463 healthy controls. Frequencies of the IL 11.A2 microsatellite allele and of IL 11.A2 homozygous individuals were significantly decreased among the patients with COPD (p < 0.012 and p < 0.022, respectively) as compared to controls. Both frequencies were even more drastically reduced among the nonsmoking patients. Tight linkage of this microsatellite allele with another polymorphism in the promotor region was established. Altered expression of IL 11 may be involved in the genetic predisposition to COPD.     

Back‐bonding in Organonickel Complexes with Terpyridine Ligands – A Structural Approach

A series of organonickel complexes [(R′terpy)Ni(aryl)]X (R′terpy = derivatives of 2,2′;6′,6″‐terpyridine; R′ = 4‐H, 4‐Cl, 4‐Tol and 4,4′,4″‐^tBu₃; aryl = 2,6‐dimethylphenyl = Xyl or 2,4,6‐trimethylphenyl = Mes; X = Br or PF₆) have been prepared and characterized. The crystal structures exhibit a number of intermolecular H bond type interactions, but the structure determining force seems to be the packing of the aryl co‐ligands. The molecules reveal rather undistorted square planar coordination with a N₃C ligand set, the central Ni–N bond being remarkably short, despite the expected strong trans influence of the aryl co‐ligands. The long‐wavelength absorptions were assigned to charge transfer transitions. No emission is observed at ambient temperature in the solid and in solution and at low temperature in glasses.     

Inclusive V0 production in pp interactions at 12 GeV/c

Results are presented on the inclusive reactions $\text{p}\text{p}\text{→}\text{K}{}^0\text{X}\text{,}\text{p}\text{p}\text{→ Λ}\text{X and}\text{p}\text{p}\text{→}\text{Λ}\text{X}$ at an incident antiproton momentum of 12 GeV/c in BEBC. The cross sections are studied as functions of the Feynman scaling variable x, the rapidity, the transverse momentum of the V⁰ and the missing mass squared. The dependence of the Λ and $\text{Λ}$ polarization on x are also studied. Comparisons with proton-proton data at 12 GeV/c are also made. Finally, events with two detected V⁰ are analyzed in order to study correlations arising from the production of two strange neutral particles.     

Analogues of Cis‐ and Transplatin with a Rich Solution Chemistry: cis‐[PtCl2(NH3)(1‐MeC‐N3)] and trans‐[PtI2(NH3)(1‐MeC‐N3)]

Mono(nucleobase) complexes of the general composition cis‐[PtCl₂(NH₃)L] with L=1‐methylcytosine, 1‐MeC ( 1 a ) and L=1‐ethyl‐5‐methylcytosine, as well as trans‐[PtX₂(NH₃)(1‐MeC)] with X=I ( 5 a ) and X=Br ( 5 b ) have been isolated and were characterized by X‐ray crystallography. The Pt coordination occurs through the N3 atom of the cytosine in all cases. The diaqua complexes of compounds 1 a and 5 a , cis‐[Pt(H₂O)₂(NH₃)(1‐MeC)]²⁺ and trans‐[Pt(H₂O)₂(NH₃)(1‐MeC)]²⁺, display a rich chemistry in aqueous solution, which is dominated by extensive condensation reactions leading to μ‐OH‐ and μ‐(1‐MeC^?‐N3,N4)‐bridged species and ready oxidation of Pt to mixed‐valence state complexes as well as diplatinum(III) compounds, one of which was characterized by X‐ray crystallography: h,t‐[{Pt(NH₃)₂(OH)(1‐MeC^?‐N3,N4)}₂](NO₃)₂ ? 2 [NH₄](NO₃) ? 2 H₂O. A combination of ¹H NMR spectroscopy and ESI mass spectrometry was applied to identify some of the various species present in solution and the gas phase, respectively. As it turned out, mass spectrometry did not permit an unambiguous assignment of the structures of +1 cations due to the possibilities of realizing multiple bridging patterns in isomeric species, the occurrence of different tautomers, and uncertainties regarding the Pt oxidation states. Additionally, compound 1 a was found to have selective and moderate antiproliferative activity for a human cervix cancer line (SISO) compared to six other human cancer cell lines.     

Antimalarials and Phytotoxins from Botryosphaeria dothidea Identified from a Seed of Diseased Torreya taxifolia

The metabolic pathways in the apicoplast organelle of Plasmodium parasites are similar to those in plastids in plant cells and are suitable targets for malaria drug discovery. Some phytotoxins released by plant pathogenic fungi have been known to target metabolic pathways of the plastid; thus, they may also serve as potential antimalarial drug leads. An EtOAc extract of the broth of the endophyte Botryosphaeria dothidea isolated from a seed collected from a Torreya taxifolia plant with disease symptoms, showed in vitro antimalarial and phytotoxic activities. Bioactivity-guided fractionation of the extract afforded a mixture of two known isomeric phytotoxins, FRT-A and flavipucine (or their enantiomers, sapinopyridione and (-)-flavipucine), and two new unstable γ-lactam alkaloids dothilactaenes A and B. The isomeric mixture of phytotoxins displayed strong phytotoxicity against both a dicot and a monocot and moderate cytotoxicity against a panel of cell lines. Dothilactaene A showed no activity. Dothilactaene B was isolated from the active fraction, which showed moderate in vitro antiplasmodial activity with high selectivity index. In spite of this activity, its instability and various other biological activities shown by related compounds would preclude it from being a viable antimalarial lead.     

Synthesis and spectroscopic Investigation of Mixed-Ligand Copper Chelates containing 2-hydroxyaryloximes and N-disubstituted dithiocarbamates. Crystal and molecular structure of trans-bis[propanone, 1-(2-hydroxy-phenyl)oximato] copper(II)

A series of mixed-ligand copper(II) chelates containing the anion of 2-hydroxyaryloxime(oxime) and N,N-disubstituted dithiocarbamate(dtc), [Cu(dtc)(oxime)], was prepared and characterised. The spectra (IR, ESR, electronic excitation) indicate that the CuNOS₂ chromophore attains square planar geometry. The ESR observables suggest appreciable covalency. In the case of [Cu(Et₂dtc)(oxime)] chelates, however, the observed data suggest distortion from square planar arrangement to a square pyramidal, indicative of a possible dimerism. In addition, the structure of the trans-bis[propanone, 1-(2-hydroxyphenyl)-oximato]copper(II), Cu(C₉H₁₀NO₂)₂ was determined by X-ray diffraction (monoclinic, space group P2₁/n, a = 12.072(7) Å, b = 5.204(2) Å, c = 13.571(6) Å, β = 103.72(1)°, Z = 2). The molecule consists of discrete Cu(ppox)₂ monomeric units, where the Cu atom is in the equatorial plane bonded to two nitrogen atoms and two oxygen at distances of 1.949(2) and 1.882(2) Å, respectively.     

On the possibility of a pH-metric determination of ozone

A novel approach for the detection and determination of ozone is presented. The method is based on monitoring the pH increase due to the reaction of ozone with an unbuffered solution of KI, during which hydroxyl ions are produced. Based on theoretical calculations, a pH increase of 0.01 pH-units corresponds to 2.3 × 10^?9 M of reacting concentration of ozone, when the initial pH of the KI solution is 7.00. Deviations from the ideal neutrality due to the presence of traces of acidic or basic impurities can be taken into account. A comparison between the expected pH changes and those experimentally achieved for given amounts of ozone has been made.     

Adsorption-induced conformational changes of proteins onto ceramic particles: differential scanning calorimetry and FTIR analysis

Three model proteins, bovine serum albumin, hen's egg lysozyme and bovine serum fibrinogen, were adsorbed from aqueous solution onto finely dispersed ceramic particles, namely different kinds of alumina and hydroxyapatite particles. The influence of adsorption on protein secondary structure was investigated. The FTIR spectroscopic findings were compared with the results of DSC measurements. In almost all cases it was found that adsorption results in destabilisation and structural loss of the bound protein. A decrease in transition enthalpy is correlated with a loss in alpha-helical structure, which seems to be the most sensitive structure on adsorption-induced rearrangements. A total collapse of structure in the adsorbed proteins was not determined on any ceramic surface. Some residual structure is always retained. Structural changes in the D- or E-domains of fibrinogen could be independently observed by two different calorimetric signals. The two techniques applied in the present study -- micro-DSC and FTIR spectroscopy -- can be concluded to provide complementary information on adsorption-induced structural changes on both the molecular (thermal stability, overall structure) and the sub-molecular level (secondary structure).