Potentiometric miniaturized pH sensors based on polypyrrole films

Potentiometric pH miniaturized sensors based on electrosynthesized polypyrrole films were developped. These pH sensors consist in two interdigitated microarray electrodes which were fabricated using photolithography process. One electrode of the sensor is coated by a polypyrrole film while the other one is coated by a silver film used as reference electrode. The potentiometric responses of these sensors were generally linear to pH changes in the range from 2 to 11. More, some sensors appeared to be stable in time during 30 days. The effect of the thickness of polymer film to potentiometric responses was also studied. It appeared that thinner polypyrrole films gave better potentiometric responses than thicker ones

Polypyrrole-Fe2O3 nanohybrid materials for electrochemical storage

We report on the synthesis and electrochemical characterization of nanohybrid polypyrrole (PPy) (PPy/Fe2O3) materials for electrochemical storage applications. We have shown that the incorporation of nanoparticles inside the PPy notably increases the charge storage capability in comparison to the “pure” conducting polymer. Incorporation of large anions, i.e., paratoluenesulfonate, allows a further improvement in the capacity. These charge storage modifications have been attributed to the morphology of the composite in which the particle sizes and the specific surface area are modified with the incorporation of nanoparticles. High capacity and stability have been obtained in PC/NEt4BF4 (at 20 mV/s), i.e., 47 mAh/g, with only a 3% charge loss after one thousand cyles. The kinetics of charge–discharge is also improved by the hybrid nanocomposite morphology modifications, which increase the rate of insertion–expulsion of counter anions in the bulk of the film. A room temperature ionic liquid such as imidazolium trifluoromethanesulfonimide seems to be a promising electrolyte because it further increases the capacity up to 53 mAh/g with a high stability during charge–discharge processes

N-glycosylation of mouse TRAIL-R and human TRAIL-R1 enhances TRAIL-induced death.

APO2L/TRAIL (TNF-related apoptosis-inducing ligand) induces death of tumor cells through two agonist receptors, TRAIL-R1 and TRAIL-R2. We demonstrate here that N-linked glycosylation (N-glyc) plays also an important regulatory role for TRAIL-R1-mediated and mouse TRAIL receptor (mTRAIL-R)-mediated apoptosis, but not for TRAIL-R2, which is devoid of N-glycans. Cells expressing N-glyc-defective mutants of TRAIL-R1 and mouse TRAIL-R were less sensitive to TRAIL than their wild-type counterparts. Defective apoptotic signaling by N-glyc-deficient TRAIL receptors was associated with lower TRAIL receptor aggregation and reduced DISC formation, but not with reduced TRAIL-binding affinity. Our results also indicate that TRAIL receptor N-glyc impacts immune evasion strategies. The cytomegalovirus (CMV) UL141 protein, which restricts cell-surface expression of human TRAIL death receptors, binds with significant higher affinity TRAIL-R1 lacking N-glyc, suggesting that this sugar modification may have evolved as a counterstrategy to prevent receptor inhibition by UL141. Altogether our findings demonstrate that N-glyc of TRAIL-R1 promotes TRAIL signaling and restricts virus-mediated inhibition

Electrochemical polymerization of 1,2-ethanedithiol as a new way to synthesize polyethylenedisulfide

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Control of carbon nanotube handedness using a supramolecular chiral surface

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Analyzing ab initio infrared spectra and electronic properties of polyethylenimine water complexes in the solid state

International audienceWe focused our study on the hydrated polyethylenimine (PEI) crystals which are characterized by the presence of 0.5, 1.5 or 2 water molecules per ethylenimine monomer unit. We propose a theoretical study in the framework of periodic linear combination of atomic orbitals (LCAO) using different Hamiltonians based on density functional theory (DFT) and hybrid Hartree-Fock (HF) - DFT level of theory. Once hydrogen atoms added when missing and redundant atoms withdrawn in the PEI structures, ab initio calculations yielded relaxed geometries at the ground state. The closest structural parameters to the experimental values are observed for hybrid Hamiltonians and the use of the 6-31++G* basis set reduces this difference. We provide the IR vibration modes at the Gamma point, with assignments of the bands. The electronic study reveals that these PEI hydrates have an insulating character with a quasi constant band gap whatever the number of water molecules. From the projected density of states (PDOS), we have found that the nitrogen orbital has the major contribution to the valence band, while the conduction band is mainly constructed from hydrogen bondings