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Serge Cosnier - One of the best experts on this subject based on the ideXlab platform.
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dawson type polyoxometalate nanoclusters confined in a carbon nanotube matrix as efficient redox mediators for enzymatic glucose biofuel cell anodes and glucose biosensors
Biosensors and Bioelectronics, 2018Co-Authors: Feriel Boussema, Serge Cosnier, Abderrazak Maaref, Andrew J Gross, Fatma Hmida, Brahim Ayed, Hatem Majdoub, Michael HolzingerAbstract:Abstract Two new inorganic-organic hybrid materials based on heteropolyoxometalates (POMs): (C 4 H 10 N) 6 [P 2 Mo 18 O 62 ]·4H 2 O (P 2 Mo 18 ) and (C 6 H 8 NO) 4 [H 2 P 2 W 18 O 62 ]·6H 2 O (P 2 W 18 ) are reported as mediators for Electron Transfer between FAD-dependent glucose dehydrogenase (FAD-GDH) and a multiwalled carbon nanotube (MWCNT) matrix for glucose biofuel cell and biosensor applications. These polyoxometalates were chosen due to their promising redox behavior in a potential range for Mediated Electron Transfer with the glucose oxidizing enzyme, FAD-GDH. P 2 Mo 18 and P 2 W 18 were immobilized on 1-pyrenemethylamine (PMA) functionalized MWCNT deposits. After immobilization of FAD-GDH, the P 2 W 18 -modified MWCNT electrode demonstrated Mediated Electron Transfer and provided a catalytic current density of 0.34 mA cm −2 at 0.2 V vs SCE with an open circuit potential (OCP) of −0.08 V vs SCE. A 10-fold increase in catalytic current to 4.7 mA cm −2 at 0.2 V vs SCE and a slightly lower OCP of −0.10 V vs SCE was observed for an equivalent electrode modified with P 2 Mo 18 .The apparent superiority of P 2 Mo 18 is related, at least in part, to its improved incorporation in the MWCNT matrix compared to P 2 W 18 . Both POM-modified bioanodes showed exceptional stabilities with 45% of their initial performances remaining after 15 days. The Mediated Electron Transfer capacities of the POMs were also evaluated in a glucose sensor setup and showed very satisfying performances for glucose detection, including a sensitivity of 0.198 mA mol L −1 cm −2 , a satisfying linear range between 1 mmol L −1 and 20 mmol L −1 , and good reproducibility for the P 2 Mo 18 electrode.
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redox active glyconanoparticles as Electron shuttles for Mediated Electron Transfer with bilirubin oxidase in solution
Journal of the American Chemical Society, 2017Co-Authors: Andrew J Gross, Fabien Giroud, Xiaohong Chen, Christophe Travelet, Redouane Borsali, Serge CosnierAbstract:We demonstrate self-assembly, characterization and bioelectrocatalysis of redox-active cyclodextrin-coated nanoparticles. The nanoparticles with host–guest functionality are easy to assemble and permit entrapment of hydrophobic redox molecules in aqueous solution. Bis-pyrene-ABTS encapsulated nanoparticles were investigated electrochemically and spectroscopically. Their use as Electron shuttles is demonstrated via an intraElectron Transfer chain between neighboring redox units of clustered particles (Dh,DLS = 195 nm) and the mono- and trinuclear Cu sites of bilirubin oxidases. Enhanced current densities for Mediated O2 reduction are observed with the redox nanoparticle system compared to equivalent bioelectrode cells with dissolved mediator. Improved catalytic stability over 2 days was also observed with the redox nanoparticles, highlighting a stabilizing effect of the polymeric architecture. Bioinspired nanoparticles as mediators for bioelectrocatalysis promises to be valuable for future biofuel cells an...
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Redox-Active Glyconanoparticles as Electron Shuttles for Mediated Electron Transfer with Bilirubin Oxidase in Solution
2017Co-Authors: Andrew J. Gross, Fabien Giroud, Xiaohong Chen, Christophe Travelet, Redouane Borsali, Serge CosnierAbstract:We demonstrate self-assembly, characterization and bioelectrocatalysis of redox-active cyclodextrin-coated nanoparticles. The nanoparticles with host–guest functionality are easy to assemble and permit entrapment of hydrophobic redox molecules in aqueous solution. Bis-pyrene-ABTS encapsulated nanoparticles were investigated electrochemically and spectroscopically. Their use as Electron shuttles is demonstrated via an intraElectron Transfer chain between neighboring redox units of clustered particles (Dh,DLS = 195 nm) and the mono- and trinuclear Cu sites of bilirubin oxidases. Enhanced current densities for Mediated O2 reduction are observed with the redox nanoparticle system compared to equivalent bioelectrode cells with dissolved mediator. Improved catalytic stability over 2 days was also observed with the redox nanoparticles, highlighting a stabilizing effect of the polymeric architecture. Bioinspired nanoparticles as mediators for bioelectrocatalysis promises to be valuable for future biofuel cells and biosensors
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freestanding redox buckypaper electrodes from multi wall carbon nanotubes for bioelectrocatalytic oxygen reduction via Mediated Electron Transfer
Chemical Science, 2014Co-Authors: M Bourourou, Kamal Elouarzaki, Michael Holzinger, Charles Agnes, Alan Le Goff, Nadege Reverdybruas, Didier Chaussy, Mikael Party, Abderrazak Maaref, Serge CosnierAbstract:An efficient and easy way of designing free standing redox buckypaper electrodes via the elegant combination of multi-walled carbon nanotubes (MWCNTs) and a bis-pyrene derivative is reported. This bis-pyrene 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (bis-Pyr-ABTS) acts as a cross-linker between the nanotubes and assures the formation of a mechanically reinforced buckypaper, obtained by a classical filtration technique of a MWCNT suspension in the presence of bis-Pyr-ABTS. In addition, the ABTS derivative assures a Mediated Electron Transfer to laccase. The electroactive buckypapers were characterized in terms of morphology, conductivity, and electrochemical properties. Two setups were evaluated. The first consisted of the immobilization and wiring of laccase enzymes via an inclusion complex formation between the hydrophobic cavity of laccase and the pyrene groups of bis-Pyr-ABTS that are not π-stacked to the nanotubes. The second approach was to evaluate the Mediated Electron Transfer using laccase in solution. For this setup, the developed mediator electrodes demonstrated high performances with maximum currents up to 2 mA ± 70 μA and an excellent operational stability for two weeks with daily one hour discharges using refreshed laccase solutions.
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three dimensional carbon nanotube polypyrrole nife hydrogenase electrodes for the efficient electrocatalytic oxidation of h2
International Journal of Hydrogen Energy, 2011Co-Authors: Jessica Baur, Michael Holzinger, Alan Le Goff, Sebastien Dementin, Marc Rousset, Serge CosnierAbstract:Abstract Hydrogenase electrodes for hydrogen oxidation are elaborated by an innovative immobilization strategy of [NiFe] hydrogenases from Desulfovibrio fructosovorans on highly porous single-walled (SWCNT) and multi-walled (MWCNT) carbon nanotube electrodes. The bioelectrode fabrication involved the adsorption of hydrogenase and amphiphilic pyrrole monomer functionalized by a methylviologen moiety on the nanotube deposits. The electropolymerization of the adsorbed monomer then leads to the enzyme entrapment in polypyrrole film surrounding the nanotubes. In addition, the redox polypyrrole achieves an efficient electrical wiring of hydrogenase on SWCNT and MWCNT electrodes via a Mediated Electron Transfer. The latter configuration showed improved performances in catalytic responses (up to 0.30 ± 0.01 mA cm −2 ) at stationary electrodes due to the more appropriate wettability of MWCNTs. This led to a better coating of the nanostructured surface and thus, to an enhanced Mediated Electron Transfer between the enzyme and the nanotubes.
Ronny Neumann - One of the best experts on this subject based on the ideXlab platform.
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oxygenation of methylarenes to benzaldehyde derivatives by a polyoxometalate Mediated Electron Transfer oxygen Transfer reaction in aqueous sulfuric acid
Journal of the American Chemical Society, 2015Co-Authors: Bidyut Bikash Sarma, Irena Efremenko, Ronny NeumannAbstract:The synthesis of benzaldehyde derivatives by oxygenation of methylarenes is of significant conceptual and practical interest because these compounds are important chemical intermediates whose synthesis is still carried out by nonsustainable methods with very low atom economy and formation of copious amounts of waste. Now an oxygenation reaction with a 100% theoretical atom economy using a polyoxometalate oxygen donor has been found. The product yield is typically above 95% with no “overoxidation” to benzoic acids; H2 is released by electrolysis, enabling additional reaction cycles. An electrocatalytic cycle is also feasible. This reaction is possible through the use of an aqueous sulfuric acid solvent, in an aqueous biphasic reaction mode that also allows simple catalyst recycling and recovery. The solvent plays a key role in the reaction mechanism by protonating the polyoxometalate thereby enabling the activation of the methylarenes by an Electron Transfer process. After additional proton Transfer and ox...
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polyoxometalate Mediated Electron Transfer oxygen Transfer oxidation of cellulose and hemicellulose to synthesis gas
Nature Communications, 2014Co-Authors: Bidyut Bikash Sarma, Ronny NeumannAbstract:Terrestrial plants contain ~70% hemicellulose and cellulose that are a significant renewable bioresource with potential as an alternative to petroleum feedstock for carbon-based fuels. The efficient and selective deconstruction of carbohydrates to their basic components, carbon monoxide and hydrogen, so called synthesis gas, is an important key step towards the realization of this potential, because the formation of liquid hydrocarbon fuels from synthesis gas are known technologies. Here we show that by using a polyoxometalate as an Electron Transfer-oxygen Transfer catalyst, carbon monoxide is formed by cleavage of all the carbon-carbon bonds through dehydration of initially formed formic acid. In this oxidation-reduction reaction, the hydrogen atoms are stored on the polyoxometalate as protons and Electrons, and can be electrochemically released from the polyoxometalate as hydrogen. Together, synthesis gas is formed. In a hydrogen economy scenario, this method can also be used to convert carbon monoxide to hydrogen.
Jacqueline K. Barton - One of the best experts on this subject based on the ideXlab platform.
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ultrafast dynamics in dna Mediated Electron Transfer base gating and the role of temperature
Angewandte Chemie, 2003Co-Authors: Melanie A Oneill, Chaozhi Wan, Jacqueline K. Barton, Hanschristian Becker, Ahmed H. ZewailAbstract:The ultrafast dynamics of Electron Transfer (ET) between bases in DNA have been determined to elucidate the critical role of base-pair gating on the timescale of the Electron transport and the temperature dependence of the rates. ET occurs only through DNA duplexes that adopt a specific, well-coupled alignment of bases (ET-active; see picture). Descriptions of ET dynamics must include fluctuations of DNA bases.
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femtosecond dynamics of dna Mediated Electron Transfer
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Torsten Fiebig, Shana O. Kelley, Jacqueline K. Barton, Christopher R Treadway, Ahmed H. ZewailAbstract:Diverse biophysical and biochemical studies have sought to understand Electron Transfer (ET) in DNA in part because of its importance to DNA damage and its repair. However, the dynamics and mechanisms of the elementary processes of ET in this medium are not fully understood and have been heavily debated. Two fundamental issues are the distance over which charge is transported and the time-scale on which the transport through the pi-stack of the DNA base pairs may occur. With femtosecond resolution, we report direct observation in DNA of ultrafast ET, initiated by excitation of tethered ethidium (E), the intercalated Electron acceptor (A); the Electron donor (D) is 7-deazaguanine (Z), a modified base, placed at different, fixed distances from A. The ultrafast ET between these reactants in DNA has been observed with time constants of 5 ps and 75 ps and was found to be essentially independent of the D-A separation (10-17 A). However, the ET efficiency does depend on the D-A distance. The 5-ps decay corresponds to direct ET observed from 7-deazaguanine but not guanine to E. From measurements of orientation anisotropies, we conclude that the slower 75-ps process requires the reorientation of E before ET, similar to E/nucleotide complexes in water. These results reveal the nature of ultrafast ET and its mechanism: in DNA, ET cannot be described as in proteins simply by a phenomenological parameter, beta. Instead, the involvement of the base pairs controls the time scale and the degree of coherent transport.
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Femtosecond dynamics of the DNA intercalator ethidium and Electron Transfer with mononucleotides in water
Proceedings of the National Academy of Sciences of the United States of America, 1999Co-Authors: Torsten Fiebig, Chaozhi Wan, Shana O. Kelley, Jacqueline K. Barton, Ahmed H. ZewailAbstract:Ethidium (E) is a powerful probe of DNA dynamics and DNA-Mediated Electron Transfer (ET). Molecular dynamical processes, such as solvation and orientation, are important on the time scale of ET. Here, we report studies of the femtosecond and picosecond time-resolved dynamics of E, E with 2'deoxyguanosine triphosphate (GTP) in water, and E with 7-deaza-2'-deoxyguanosine triphosphate (ZTP) in water; E undergoes ET with ZTP but not GTP. These studies elucidate the critical role of relative orientational motions of the donor-acceptor complex on ET processes in solution. For ET from ZTP to E, such motions are in fact the rate-determining step. Our results indicate that these complexes reorient before ET. The time scale for the solvation of E in water is 1 ps, and the orientational relaxation time of E is 70 ps. The impact of orientational and solvation effects on ET between E and mononucleotides must be considered in the application of E as a probe of DNA ET.
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Electron Transfer between bases in double helical dna
Science, 1999Co-Authors: Shana O. Kelley, Jacqueline K. BartonAbstract:Fluorescent analogs of adenine that selectively oxidize guanine were used to investigate photoinduced Electron Transfer through the DNA π-stack as a function of reactant stacking and energetics. Small variations in these factors led to profound changes in the kinetics and distance dependences of DNA-Mediated Electron-Transfer reactions. Values of β, a parameter reflecting the dependence of Electron Transfer on distance, ranged from 0.1 to 1.0 per angstrom. Strong stacking interactions result in the fastest Electron-Transfer kinetics. Electrons are thus transported preferentially through an intrastrand rather than interstrand pathway. Reactant energetics also modulate the distance dependence of DNA-Mediated charge transport. These studies may resolve the range of disparate results previously reported, and paradigms must now be developed to describe these properties of the DNA π-stack, which can range from insulator- to “wire”-like.
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dna Mediated Electron Transfer from a modified base to ethidium π stacking as a modulator of reactivity
Chemistry & Biology, 1998Co-Authors: Shana O. Kelley, Jacqueline K. BartonAbstract:Background: The DNA double helix is composed of an array of aromatic heterocyclic base pairs and, as a molecular π-stack, represents a novel system for studying long-range Electron Transfer. Because many base damage and repair processes result from Electron-Transfer reactions, the ability of DNA to mediate charge transport holds important biological implications. Seemingly contradictory conclusions have been drawn about Electron Transfer in DNA from the many different studies that have been carried out. These studies must be reconciled so that this phenomenon can be understood both at a fundamental level and in the context of biological systems. Results: The photoinduced oxidation of a modified base, 7-deazaguanine, has been examined as a function of distance, sequence, and base stacking in DNA duplexes covalently modified with ethidium. Over ethidium/deazaguanine separations of 6–27 A, the photooxidation reaction proceeded on a subnanosecond time scale, and the quenching yield exhibited a shallow distance dependence. The efficiency of the reaction was highly sensitive to small changes in base composition. Moreover, the overall distance-dependence of the reaction is sensitive to sequence, despite the constancy of photoexcited ethidium as acceptor. Conclusions: The remarkable efficiency of deazaguanine photooxidation by intercalated ethidium over long distances provides new evidence for fast Electron-Transfer pathways through DNA. By varying sequence as well as reactant separation, this work provides the first experimental demonstration of the importance of reactant stacking in the modulation of long-range DNA-Mediated Electron Transfer.
Jose A Garrido - One of the best experts on this subject based on the ideXlab platform.
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surface state Mediated Electron Transfer across the n type sic electrolyte interface
Journal of Physical Chemistry C, 2016Co-Authors: Matthias Sachsenhauser, Ian D Sharp, M Stutzmann, Jose A GarridoAbstract:Understanding the mechanisms of charge Transfer across the semiconductor/electrolyte interface is a basic prerequisite for a variety of practical applications. In particular, electrically active surface states located in the semiconductor band gap are expected to play an important role, but direct experimental evidence of surface states has proven to be challenging, and further experimental studies are required to verify their influence on the exchange of charge carriers between semiconductor and electrolyte. Due to its wide band gap, chemical stability, and controllable surface termination, silicon carbide (SiC) provides an excellent model system for this purpose. In this report, we provide a fundamental electrochemical study of n-type 6H-SiC and 4H-SiC electrodes in aqueous electrolytes containing the ferricyanide/ferrocyanide redox couple. Cyclic voltammetry and impedance spectroscopy measurements are performed over a wide range of potentials to determine the energetic positions of the SiC band edges a...
Bidyut Bikash Sarma - One of the best experts on this subject based on the ideXlab platform.
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oxygenation of methylarenes to benzaldehyde derivatives by a polyoxometalate Mediated Electron Transfer oxygen Transfer reaction in aqueous sulfuric acid
Journal of the American Chemical Society, 2015Co-Authors: Bidyut Bikash Sarma, Irena Efremenko, Ronny NeumannAbstract:The synthesis of benzaldehyde derivatives by oxygenation of methylarenes is of significant conceptual and practical interest because these compounds are important chemical intermediates whose synthesis is still carried out by nonsustainable methods with very low atom economy and formation of copious amounts of waste. Now an oxygenation reaction with a 100% theoretical atom economy using a polyoxometalate oxygen donor has been found. The product yield is typically above 95% with no “overoxidation” to benzoic acids; H2 is released by electrolysis, enabling additional reaction cycles. An electrocatalytic cycle is also feasible. This reaction is possible through the use of an aqueous sulfuric acid solvent, in an aqueous biphasic reaction mode that also allows simple catalyst recycling and recovery. The solvent plays a key role in the reaction mechanism by protonating the polyoxometalate thereby enabling the activation of the methylarenes by an Electron Transfer process. After additional proton Transfer and ox...
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polyoxometalate Mediated Electron Transfer oxygen Transfer oxidation of cellulose and hemicellulose to synthesis gas
Nature Communications, 2014Co-Authors: Bidyut Bikash Sarma, Ronny NeumannAbstract:Terrestrial plants contain ~70% hemicellulose and cellulose that are a significant renewable bioresource with potential as an alternative to petroleum feedstock for carbon-based fuels. The efficient and selective deconstruction of carbohydrates to their basic components, carbon monoxide and hydrogen, so called synthesis gas, is an important key step towards the realization of this potential, because the formation of liquid hydrocarbon fuels from synthesis gas are known technologies. Here we show that by using a polyoxometalate as an Electron Transfer-oxygen Transfer catalyst, carbon monoxide is formed by cleavage of all the carbon-carbon bonds through dehydration of initially formed formic acid. In this oxidation-reduction reaction, the hydrogen atoms are stored on the polyoxometalate as protons and Electrons, and can be electrochemically released from the polyoxometalate as hydrogen. Together, synthesis gas is formed. In a hydrogen economy scenario, this method can also be used to convert carbon monoxide to hydrogen.