Hybrid Enzymatic and Organic Electrocatalytic Cascade for the Complete Oxidation of Glycerol

Hickey, David P.; McCammant, Matthew S.; Giroud, Françoise; Sigman, Matthew S.

doi:10.1021/ja5098379

Cited by 105 publications

(117 citation statements)

References 32 publications

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“…Recent progress for example in multi-catalyst "cascade" catalytic systems offers new promise for better performance in complex multi-electron reactions such as glycerol oxidation [6]. New and better catalyst systems are still desirable and in particular metal-free and enzymeless processes based on molecular organo-catalysts are attractive [7,8].…”

Section: Introductionmentioning

confidence: 99%

Electrocatalytic Carbohydrate Oxidation with 4-Benzoyloxy-TEMPO Heterogenised in a Polymer of Intrinsic Microporosity

Kolodziej

Ahn

Carta

et al. 2015

Electrochimica Acta

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electrocatalysis fuel cell carbohydrate sensor multi-electron EC'mechanism catalyst heterogenisation A B S T R A C TThe enzymeless and operationally simple electrocatalytic oxidation of carbohydrates by "heterogenised" 4-benzoyloxy-TEMPO either (i) immobilised as microcrystals at a glassy carbon electrode surface or (ii) embedded into a polymer of intrinsic microporosity (PIM-EA-TB with 1027 m 2 g À1 BET surface area and highly rigid framework structure) has been studied in aqueous phosphate buffer of pH 12. It is shown that in contrast to microcrystal deposits, 4-benzolyoxy-TEMPO co-immobilised within PIM-EA-TB give stable catalytic responses for both, stationary and rotating disc electrode systems and for oxidation of glucose, sorbitol, and sucrose. The rigidity and intrinsic microporosity of PIM-EA-TB allow (slow) substrate and product diffusion, whilst maintaining 4-benzoyloxy-TEMPO immobilised in active molecular form.

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Section: Introductionmentioning

confidence: 99%

Electrocatalytic Carbohydrate Oxidation with 4-Benzoyloxy-TEMPO Heterogenised in a Polymer of Intrinsic Microporosity

Kolodziej

Ahn

Carta

et al. 2015

Electrochimica Acta

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“…Hydroxyl group oxidation is a fundamentally important reaction with a broad range of applications in synthetic bio-transformations [7][8][9] and radical initiated polymerisation reactions [10], in sensors [11] and in complex catalyst systems for biofuel cells [12]. It is of interest to develop modified substrates with TEMPO Electronic supplementary material The online version of this article (doi:10.1007/s12678-015-0284-8) contains supplementary material, which is available to authorized users.…”

Section: Introductionmentioning

confidence: 99%

“…The TEMPOcatalysed oxidation of primary alcohol groups proceeds via overall two-electron oxidation of the alcohol requiring two equivalents of TEMPO + . Most studies have reported that TEMPO exhibits good selectivity towards primary alcohol oxidations in alkaline conditions (to aldehydes or to carboxylates [17,18]), but there are also more complex examples of secondary alcohols being oxidised to ketones [19] and examples of novel multi-catalyst multi-step oxidations [12].…”

Section: Introductionmentioning

confidence: 99%

Polymer of Intrinsic Microporosity Induces Host-Guest Substrate Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol Oxidations

et al. 2015

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The free radical 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (4B-TEMPO) is active as an electrocatalyst for primary alcohol oxidations when immobilised at an electrode surface and immersed into an aqueous carbonate buffer solution. In order to improve the catalytic process, a composite film electrode is developed based on (i) carbon microparticles of 2-12 μm diameter to enhance charge transport and (ii) a polymer of intrinsic microporosity (here PIM-EA-TB with a BET surface area of 1027 m 2 g −1 ). The latter acts as a highly rigid molecular framework for the embedded free radical catalyst with simultaneous access to aqueous phase and substrate. The resulting mechanism for the oxidation of primary alcohols is shown to switch in reaction order from first to zeroth with increasing substrate concentration consistent with a kinetically limited process with competing diffusion of charge at the polymer layer-electrode interface (here the BLEk^case in Albery-Hillman notation). Reactivity optimisation and screening for a wider range of primary alcohols in conjunction with DFT-based relative reactivity correlation reveals substrate hydrophobicity as an important factor for enhancing catalytic currents. The PIM-EA-TB host matrix is proposed to control substrate partitioning and thereby catalyst reactivity and selectivity.

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“…A low activity is observed at acidic pH, because below the pKa of hydroxylamine, the coupled deprotonation/ oxidation is no longer facilitated. 14 However, the oxidation signal remains significant above pH 4, demonstrating that TEMPO could work with H 2 O 2 -producing oxidases that operate in acidic pH ranges.…”

Section: Resultsmentioning

confidence: 99%

TEMPO as a Promising Electrocatalyst for the Electrochemical Oxidation of Hydrogen Peroxide in Bioelectronic Applications

Abdellaoui

Knoche

Lim

et al. 2015

J. Electrochem. Soc.

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A number of bioelectronic applications work with oxidase enzymes and many of them can operate with small molecule or polymer redox mediators. However, for some oxidases, there are no known redox mediators able to mediate electron transfer. Therefore, electron transfer must occur through peroxide production and oxidation at the electrode surface. Organic redox catalysts such as oxoammonium cations, are able to oxidize H 2 O 2 to form nitroxyl radicals, which can be electro-oxidized and regenerate the oxoammonium cation form. In this study, we investigate the ability to use TEMPO as a platform for the electrocatalytic oxidation of H 2 O 2 at different pHs. The results have shown that TEMPO can be used to monitor H 2 O 2 in broad pH range (≥4) at 530 mV (vs SCE). Combining TEMPO with cholesterol oxidase, we have shown the possibility to monitor the cholesterol oxidation with a linear range between 20 μM and 2.5 mM with a sensitivity of 54.86 mA cm −2 M −1 . Furthermore, we have studied the electrocatalytic oxidation of oxalate by oxalate oxidase for biofuel cell applications. These combined results demonstrate TEMPO as a promising electrocatalyst applied for the development of electrochemical biosensors or enzymatic biofuel cells. Hydrogen peroxide (H 2 O 2 ) is an enzymatic product of oxygen (O 2 ) reduction, which can be catalyzed by an exhaustive list of oxidase enzymes including glucose oxidase, alcohol oxidase, lactate oxidase, urate oxidase, cholesterol oxidase, D-amino acid oxidase, glutamate oxidase, lysine oxidase, and oxalate oxidase. Hydrogen peroxide is the smallest and simplest peroxide and is of great interest in multiple fields as a disinfectant, as a propellant in the aerospace industry, and as a biomarker for biological decomposition in the food industry.1 It also applied in the defense system of some insects, 2 the immune system, 3 and regulation of cellular processes. 4 Development of enzymatic biosensors presents a significant utility for the detection and quantification of the large number of oxidase substrates for fundamental studies as well as diagnostic and industry applications. Different techniques for the detection of oxidase substrates that have been described in the literature include spectrophotometry, 5 fluorimetry, 6 chemiluminescence, 7 and fluorescence, 8 but most of them are costly and time consuming. Hydrogen peroxide can be oxidized electrochemically, and thus electrochemical techniques have also been used as detection methods. Electrochemistry is commonly described as a simpler, cheaper, faster, and more sensitive detection technique for the development of oxidase substrate biosensors and enzymatic biofuel cells. 9,10The direct electrochemical oxidation and reduction of H 2 O 2 require high overpotentials (>+0.65 V for oxidation and >−1.7 V for reduction versus NHE). These high potentials limit analytical applications involving the oxidation or reduction of H 2 O 2 in complex media, because media electrolysis causes interference and can foul the electrode surface. In order to d...

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Hybrid Enzymatic and Organic Electrocatalytic Cascade for the Complete Oxidation of Glycerol

Cited by 105 publications

References 32 publications

Electrocatalytic Carbohydrate Oxidation with 4-Benzoyloxy-TEMPO Heterogenised in a Polymer of Intrinsic Microporosity

Electrocatalytic Carbohydrate Oxidation with 4-Benzoyloxy-TEMPO Heterogenised in a Polymer of Intrinsic Microporosity

Polymer of Intrinsic Microporosity Induces Host-Guest Substrate Selectivity in Heterogeneous 4-Benzoyloxy-TEMPO-Catalysed Alcohol Oxidations

TEMPO as a Promising Electrocatalyst for the Electrochemical Oxidation of Hydrogen Peroxide in Bioelectronic Applications

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