How do H2 oxidation molecular catalysts assemble onto carbon nanotube electrodes? A crosstalk between electrochemical and multi-physical characterization techniques

Molecular catalysts show powerful catalytic efficiency and unsurpassed selectivity in many reactions of interest. As their implementation in electrocatalytic devices requires their immobilization onto a conductive support, controlling the grafting chemistry and its impact on their distribution at the surface of this support within the catalytic layer is key to enhancing and stabilizing the current they produce. This study focuses on molecular bioinspired nickel catalysts for hydrogen oxidation, bound to carbon nanotubes, a conductive support with high specific area. We couple advanced analysis by transmission electron microscopy (TEM), for direct imaging of the catalyst layer on individual nanotubes, and small angle neutron scattering (SANS), for indirect observation of structural features in a relevant aqueous medium. Low-dose TEM imaging shows a homogeneous, mobile coverage of catalysts, likely as a monolayer coating the nanotubes, while SANS unveils a regular nanostructure in the catalyst distribution on the surface with agglomerates that could be imaged by TEM upon aging. Together, electrochemistry, TEM and SANS analyses allowed drawing an unprecedented and intriguing picture with molecular catalysts evenly distributed at the nanoscale in two different populations required for optimal catalytic performance.

How do efficient hydrogen-oxidation molecular electrocatalysts connect onto their carbon nanotube conductive support? A coupled neutron scattering SANS and STEM electron microscopy study to observe soft active matter organizing on 3D nanosurfaces.     

Myotoxin-3 from the Pacific Rattlesnake Crotalus oreganus oreganus Venom Is a New Microtubule-Targeting Agent

Microtubule targeting agents (MTA) are anti-cancer molecules that bind tubulin and interfere with the microtubule functions, eventually leading to cell death. In the present study, we used an in vitro microtubule polymerization assay to screen several venom families for the presence of anti-microtubule activity. We isolated myotoxin-3, a peptide of the crotamine family, and three isoforms from the venom of the Northern Pacific rattlesnake Crotalus oreganus oreganus, which was able to increase tubulin polymerization. Myotoxin-3 turned out to be a cell-penetrating peptide that slightly diminished the viability of U87 glioblastoma and MCF7 breast carcinoma cells. Myotoxin 3 also induced remodeling of the U87 microtubule network and decreased MCF-7 microtubule dynamic instability. These effects are likely due to direct interaction with tubulin. Indeed, we showed that myotoxin-3 binds to tubulin heterodimer with a Kd of 5.3 µM and stoichiometry of two molecules of peptide per tubulin dimer. Our results demonstrate that exogenous peptides are good candidates for developing new MTA and highlight the richness of venoms as a source of pharmacologically active molecules.     

Recent Advances in Pain Management: Relevant Protein Kinases and Their Inhibitors

The purpose of this review is to underline the protein kinases that have been established, either in fundamental approach or clinical trials, as potential biological targets in pain management. Protein kinases are presented according to their group in the human kinome: TK (Trk, RET, EGFR, JAK, VEGFR, SFK, BCR–Abl), CMGC (p38 MAPK, MEK, ERK, JNK, ASK1, CDK, CLK2, DYRK1A, GSK3, CK2), AGC (PKA, PKB, PKC, PKMζ, PKG, ROCK), CAMK, CK1 and atypical/other protein kinases (IKK, mTOR). Examples of small molecule inhibitors of these biological targets, demonstrating an analgesic effect, are described. Altogether, this review demonstrates the fundamental role that protein kinase inhibitors could play in the development of new pain treatments.     

Development,Validation, and Performance of Chitosan‐Based Coatings Using Catechol Coupling

The use of long‐lasting polymer coatings on biodevice surfaces has been investigated to improve material–tissue interaction, minimize adverse effects, and enhance their functionality. Natural polymers, especially chitosan, are of particular interest due to their excellent biological properties, such as biocompatibility, non‐toxicity, and antimicrobial properties. One way to produce chitosan coating is by covalent grafting with catechol molecules such as dopamine, caffeic acid, and tannic acid, resulting in an attachment ten times stronger than that of simple physisorption. Caffeic acid presents an advantage over dopamine because it allows direct chitosan grafting, due to its terminal carboxylic acid group, without the need of a linking arm, as employed in the dopamine approach. In this study, the grafting of chitosan using caffeic acid, over surfaces or in solution, is compared with dopamine grafting using poly(ethylene glycol) as a linking arm. The following coating properties are observed; covering and homogeneity are assessed by X‐ray photoelectron spectroscopy and atomic force microscopy analyses, hydrophilicity with contact angle measurements, stability with aging tests, anticorrosion behavior, and coating non‐toxicity. Results show that grafting using caffeic acid/chitosan in solution over a metallic surface may be advantageous, compared to traditional dopamine coating.     

On the Minimum Distances of Non-Binary Cyclic Codes

We deal with the minimum distances of q-ary cyclic codes of length q ^m - 1 generated by products of two distinct minimal polynomials, give a necessary and sufficient condition for the case that the minimum distance is two, show that the minimum distance is at most three if q > 3, and consider also the case q = 3.     

Protection and Labelling of Thymidine by a Fluorescent Photolabile Group

A fluorescent photolabile group including coumarin and MeNPOC moieties was synthesized to protect 5′‐OH terminal function of thymidine (T). Its photochemical and photophysical properties were studied, in particular the photocleavage (photodeprotection under a 365‐nm irradiation) is only lowered by a factor of two by addition of the fluorophore. Fluorescence properties of the coumarin probe are not changed upon irradiation, which is satisfactory for the application required, i.e., in situ synthesis of DNA microarrays.     

Benzodiselenagermoles and spirobisbenzodiselenagermoles

Synthesis of benzodiselenagermoles and bisbenzodiselenagermoles was carried out by transmetallation group 4 → group 14 between diselenophenylenezirconocenes and dialkyl-, diaryl- or alkylaryldichlorogermanes, aryltrichlorogermane or germanium tetrachloride. The new compounds were studied by ¹H, ⁷⁷Se NMR and mass spectrometry. In the case of compounds with substituted phenyl groups, double irradiation and 2D NMR experiments were performed to determine the chemical shifts of the two selenium atoms. The crystal structure of a spirobisbenzodiselenagermole has been established by X-ray diffraction analysis.     

Graft modification of crystalline nanocellulose by Cu(0)‐mediated SET living radical polymerization

Crystalline nanocellulose (CNC) was grafted with poly(methyl acrylate) (PMA) to yield modified CNC that is readily dispersed in a range of organic solvents [including tetrahydrofuran, chloroform, dimethylformamide, and dimethyl sulfoxide (DMSO)], in contrast to native CNC which is dispersible primarily in aqueous solutions. First, a CNC macroinitiator with high bromine initiator density was prepared through a 1,1′‐carbonyldiimidazole‐mediated esterification reaction in DMSO‐based dispersant. MA was then grafted from the CNC macroinitiator through SET living radical polymerization (LRP) at room temperature using Cu(0) (copper wire) as the catalyst. The LRP grafting proceeded rapidly, with ～30% monomer conversion achieved within 30 min, yielding approximately six times the mass of PMA with respect to CNC macroinitiator. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2800–2808