Affinity of human thrombin for insoluble polystyrene substituted with sulfonate,n-hydroxyethylsulfamoyl and n-substituted amidine functions

A new polymeric material was prepared from polystyrene beads with N-substituted amidines and rendered hydrophilic with sulfonate and N-hydroxyethylsulfamoyl groups. It was synthesized by reacting the p-chlorosulfonyl polystyrene with ethanolamine followed by the Michael-like addition of the terminal OH of the polymer (PSEa) to N-t-butyl-N'-phenylpropenamidine 1 thus leading to the final polymer PSEaAm. Its affinity constant for human α-thrombin calculated from the Langmuir adsorption isotherms was about 10⁶ M⁻¹, a value comparable to the one estimated for polystyrene modified with L-arginine methyl ester. This new material was used as stationary phase in affinity chromatography of thrombin confirming a strong and specific interaction between the positively charged amidinium groups and the enzyme at pH = 7.4 and desorption at pH = 10 and high ionic strength.     

3‐[2,6‐Bis­(diethyl­carbamoyl)­pyridin‐4‐yl]‐N‐(tert‐butoxy­carbonyl)­alanine methyl ester: a chiral tridentate ligand that causes a diastereomeric excess of its lanthanide complexes in solution

L⁴, or 3‐[2,6‐bis­(diethyl­carbamoyl)­pyridin‐4‐yl]‐N‐(tert‐but­oxy­car­bonyl)­alanine methyl ester, C₂₄H₃₈N₄O₆, crystallizes in neat [010] laths stabilized by abundant intra‐ and intermolecular hydrogen bonds. The strongest of these form [010] chains of mol­ecules, thus rationalizing the fastest growth direction, while the slowest direction coincides with the normal to the (110) layers, which are linked by very weak hydrogen bonds. There exist two independent mol­ecules, the distances and bond angles of which differ in a random manner only. The torsion and dihedral angles, however, differ so as to achieve optimal packing. The influence of the chiral group in the 4‐position of the pyridine ring on the helical wrapping and on the ensuing diastereomeric induction is briefly discussed.     

Properties of GeSi Nanocrystals Embedded in Hexagonal SiC

In this paper high‐resolution electron microscopy investigations and molecular dynamics simulations of GeSi nanocrystals buried in 4H‐SiC are performed, showing that the experimentally observed shapes of the GeSi nanocrystals are strongly correlated with their orientational relationships. Measurements of the lattice spacing suggest that the nanocrystals are strained. Quantum confinement in selected nanocrystals has been detected using spatially‐resolved electron energy loss spectroscopy performed in conjunction with atomic resolution annular dark‐field scanning TEM.     

A Hexakis Terpyridine‐Fullerene Ligand in Six‐Fold Ruthenium,Iridium, and Iron Complexes: Synthesis and Electrochemical Properties

An unprecedented straightforward route to six‐fold terpyridine ligands around C₆₀, the latter being regioselectively functionalized in pseudo‐octahedral positions using a six‐fold Bingel reaction, is reported. Ruthenium, iridium, and iron complexes have been synthesized, and unambiguously characterized by NMR, MS, and cyclic voltammetry.     

Chemical oxidation of a redox-active, ferrocene-containing cationic lipid: Influence on interactions with DNA and characterization in the context of cell transfection

We report an approach to the chemical oxidation of a ferrocene-containing cationic lipid [bis(11-ferrocenylundecyl)dimethylammonium bromide, BFDMA] that provides redox-based control over the delivery of DNA to cells. We demonstrate that BFDMA can be oxidized rapidly and quantitatively by treatment with Fe(III)sulfate. This chemical approach, while offering practical advantages compared to electrochemical methods used in past studies, was found to yield BFDMA/DNA lipoplexes that behave differently in the context of cell transfection from lipoplexes formed using electrochemically oxidized BFDMA. Specifically, while lipoplexes of the latter do not transfect cells efficiently, lipoplexes of chemically oxidized BFDMA promoted high levels of transgene expression (similar to levels promoted by reduced BFDMA). Characterization by SANS and cryo-TEM revealed lipoplexes of chemically and electrochemically oxidized BFDMA to both have amorphous nanostructures, but these lipoplexes differed significantly in size and zeta potential. Our results suggest that differences in zeta potential arise from the presence of residual Fe²⁺ and Fe³⁺ ions in samples of chemically oxidized BFDMA. Addition of the iron chelating agent EDTA to solutions of chemically oxidized BFDMA produced samples functionally similar to electrochemically oxidized BFDMA. These EDTA-treated samples could also be chemically reduced by treatment with ascorbic acid to produce samples of reduced BFDMA that do promote transfection. Our results demonstrate that entirely chemical approaches to oxidation and reduction can be used to achieve redox-based ‘on/off’ control of cell transfection similar to that achieved using electrochemical methods.     

Investigation of the synergy in intumescent polyurethane by 3D computed tomography

The morphology of carbonized materials resulting from an intumescence phenomenon was studied. The investigated material is a polyurethane matrix filled either by 30 wt.-% of ammonium polyphosphate or by a combination of 28 wt.-% of ammonium polyphosphate and 2 wt.-% of nano-magnesium oxide. These fillers were incorporated in the polyurethane directly during the synthesis step. The carbonized materials or char, are obtained in a specific fire scenario. Characterization of their morphology is carried out using X-ray computed tomography. The heat conductivity of the systems is additionally measured as a function of temperature in order to correlate structure and properties of the intumescent residues. The formation of different char structures with incorporation of magnesium oxide (in particular formation of bubbles of different size) is first evidenced. These observations are consistent with the heat conductivity data. Tomography images demonstrate that the intumescence process is a dynamic process since non degraded polymer is left at the beginning of the fire test, which is not the case for longer time. The dispersion of fillers has finally been investigated in the chars and it is evidenced different steps of intumescence's development in the material.     

The Potential Role of Polyphenols in Modulating Mitochondrial Bioenergetics within the Skeletal Muscle: A Systematic Review of Preclinical Models

Polyphenols are naturally derived compounds that are increasingly being explored for their various health benefits. In fact, foods that are rich in polyphenols have become an attractive source of nutrition and a potential therapeutic strategy to alleviate the untoward effects of metabolic disorders. The last decade has seen a rapid increase in studies reporting on the bioactive properties of polyphenols against metabolic complications, especially in preclinical models. Various experimental models involving cell cultures exposed to lipid overload and rodents on high fat diet have been used to investigate the ameliorative effects of various polyphenols against metabolic anomalies. Here, we systematically searched and included literature reporting on the impact of polyphenols against metabolic function, particularly through the modulation of mitochondrial bioenergetics within the skeletal muscle. This is of interest since the skeletal muscle is rich in mitochondria and remains one of the main sites of energy homeostasis. Notably, increased substrate availability is consistent with impaired mitochondrial function and enhanced oxidative stress in preclinical models of metabolic disease. This explains the general interest in exploring the antioxidant properties of polyphenols and their ability to improve mitochondrial function. The current review aimed at understanding how these compounds modulate mitochondrial bioenergetics to improve metabolic function in preclinical models on metabolic disease.