Electrocatalytic oxidation of reduced nicotinamide coenzymes at gold and platinum electrode surfaces modified with a monolayer of pyrroloquinoline quinone. Effect of Ca2+ cations

Katz, Eugenii; Lötzbeyer, Thomas; Schlereth, Daniela D.; Schuhmann, Wolfgang; Schmidt, Hanns‐Ludwig

doi:10.1016/0022-0728(94)03328-5

Cited by 201 publications

(116 citation statements)

References 55 publications

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“…In a series of investigations on the reaction rate for NADH oxidation at mediator modified electrodes the addition of divalent metal cations (e.g., Ca 2 and Mg 2 ) to the buffer solution revealed substantial increase in the catalytic efficiency [23, 25, 46, 49 ± 52]. In a previously published work by Katz et al [49] it was shown that equal values of k 2 are obtained using pyrroloquinoline quinone (PQQ) immobilized on gold as the catalyst both in the presence and in the absence of Ca 2 , whereas the value of K M decreased from 109 mM to 0.73 mM after addition of Ca 2 even though the E8'-value of the immobilized PQQ remained virtually constant. This means that after addition of Ca 2 a dramatic shift of the equilibrium between NADH and PQQ towards the formation of the intermediate complex takes place but the decay rate of the CT-complex leading to the formation of NAD is not changed at all.…”

Section: Effect Of Addition Of Ca 2 To the Buffer Solutionmentioning

confidence: 99%

NADH Oxidation Using Carbonaceous Electrodes Modified with Dibenzo‐Dithia‐Diazapentacene

et al. 2003

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The electrochemical and the electrocatalytic behavior for NADH oxidation of a newly synthesized phenothiazine derivative, 16H,18H-dibenzo[c,1]-7,9-dithia-16,18-diazapentacene (DDDP), adsorbed on solid spectrographic graphite and on graphite powder or on zirconium phosphate (ZP), both entrapped in carbon paste, were compared. Experiments using cyclic voltammetry and a rotating disk electrode, performed in different experimental conditions (various pH values and NADH concentrations), showed that i) in the pH range between 4 and 8, the E8× value for DDDP adsorbed on ZP becomes pH independent; ii) in contrast to other redox mediators, adsorption of DDDP on ZP induced a significant negative shift of the E8× value; iii) the reaction rate for electrocatalytic oxidation of NADH is markedly increased by adsorbing the mediator on ZP, being further improved by the presence of Ca 2 ions in the solution.

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Section: Effect Of Addition Of Ca 2 To the Buffer Solutionmentioning

confidence: 99%

NADH Oxidation Using Carbonaceous Electrodes Modified with Dibenzo‐Dithia‐Diazapentacene

et al. 2003

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“…Calcium is well-known to enhance the enzyme activity of several PQQ-containing dehydrogenases 11,19 and has been investigated with immobilized PQQ on gold and platinum electrodes. 20 Ca 2+ and Mg 2+ were omitted from the phosphate buffer because of uncertain free concentrations due to potential chelation. Figure 1 shows voltammograms of PQQ reduction-oxidation in various pH 7 buffers, using GCEs modified with the two different lengths of carboxyl-functionalized MWCNTs.…”

Section: Resultsmentioning

confidence: 99%

Electrochemistry of Pyrroloquinoline Quinone (PQQ) on Multi-Walled Carbon Nanotube-Modified Glassy Carbon Electrodes in Biological Buffers

Emahi

Mitchell

Baum

2017

J. Electrochem. Soc.

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Pyrroloquinoline quinone (PQQ) is an important electrocatalyst and redox cofactor for many enzymes used in bioanalytical applications. Careful selection of electrode modifications and buffer compositions is required due to PQQ's tendency to be irreversibly reduced on bare electrodes and the strong effect of pH on its electrochemistry. Multi-walled carbon nanotubes (MWCNTs) can effectively modify glassy carbon electrodes, but PQQ's behavior at these surfaces has not been investigated. While phosphate buffers have been used extensively to characterize PQQ's electrochemistry, phosphate buffers can act as chelating agents for important metal ions needed by PQQ and biomolecules. Different physiological buffers could overcome these challenges and expand the buffer options for biofuel cells. Using cyclic voltammetry, we studied PQQ in HEPES, MOPS, TRIS, and phosphate buffers at pH 7 with MWCNT-modified electrodes. While there were no significant differences in PQQ's behavior with the various buffers, the ionic composition of the non-phosphate buffers was very important. We observed that K + and Mg 2+ were the most influential ions for the reversible reduction-oxidation of PQQ. PQQ's electrochemistry was also affected by the length of and the functional groups on the MWCNTs, indicating that the electron transfer kinetics were quite sensitive to the surface chemistry of the electrodes. Pyrroloquinoline quinone (PQQ) is a redox cofactor found in the active sites of a number of enzymes. Most of these quinoproteins are dehydrogenases capable of catalyzing the oxidation of a broad range of substrates, such as alcohols, acids, aldehydes and sugars. 1 PQQ-dependent glucose dehydrogenase, for example, is capable of oxidizing several mono-and disaccharides, including glucose, maltose, lactose, galactose, xylose and mannose.1 The uniqueness of the quinoproteins and their broad substrate specificities have led to their use in bioanalytical applications, including biosensors and biofuel cells.In the absence of an enzyme, PQQ itself is capable of catalyzing redox reactions, including the oxidation of thiols, 2,3 amino acids, 4 and the redox cofactor nicotinamide adenine dinucleotide (NAD + ). 5The electrochemistry of PQQ has been studied quite extensively in both solution and immobilized forms via cyclic voltammetry (CV) and potentiometric titration studies. 6,7 These studies can be challenging due to the pH dependence of the redox potentials. 6,8,9 Using a cystamine-monolayer Au-modified electrode, Katz et al.6 studied the electrochemistry of PQQ in solution using CV and reported the change in potential with pH to be about 60 mV pH −1 at pH < 6.2; 30 mV pH −1 at 6.2 < pH < 8.6; and about 60 mV pH −1 at pH > 8.6. In another study using PQQ immobilized on few-walled carbon nanotube (FWCNT)-modified glassy carbon electrodes, the change in PQQ's redox potential was estimated to be approximately 67 mV pH −1 , with the highest reversible reduction-oxidation observed at ∼pH 2. The nature of the modified electrode surface can also affect P...

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“…A denominação de eletrodos quimicamente modificados foi sugerida por Murray et al na década de 70 para definir eletrodos com espécies quimicamente ativas devidamente imobilizadas na superfície desses dispositivos 8 . O EM é construído adicionando-se espécies quimicamente ativas imobilizadas no substrato do eletrodo, com o objetivo de pré-estabelecer e controlar a natureza físico-química da interface eletrodo/solução.…”

Section: Introductionunclassified

“…do modificador, possibilitando assim o desenvolvimento de dispositivos com resposta adequada para vários propósitos e aplicações. Nesse aspecto, são encontradas na literatura diversas revisões que descrevem as diferentes estratégias para construção de eletrodos modificados [3][4][5][6][7][8][9] .…”

Section: Introductionunclassified

Determinação voltamétrica por redissolução anódica de Cu(II) em águas residuárias empregando um eletrodo de pasta de carbono modificado com quitosana

Janegitz¹,

Marcolino‐Júnior²,

Fatibello‐Filho³

2007

Quím. Nova

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Recebido em 24/10/06; aceito em 9/3/07; publicado na web em 6/8/07 ANODIC STRIPPING VOLTAMMETRIC DETERMINATION OF COPPER (II) IN WASTEWATERS USING A CARBON PASTE ELECTRODE MODIFIED WITH CHITOSAN. The electrochemical applications of a CPE modified with chitosan for the determination of Cu(II) in wastewater samples using anodic stripping voltammetry are described. The best voltammetric response was observed for a paste containing 25% m/m of chitosan. A 0.10 mol L -1 NaNO 3 solution (pH 6.5) as supporting electrolyte, a pre-concentration potential of -0.20 V, pre-concentration time of 270 s and a scan rate of 25 mV s -1 were selected. The calibration graph was linear in the Cu(II) concentration range from 2.0 x 10 -7 to 7.4 x 10 -6 mol L -1 , with a detection limit of 8.3 x 10 -8 mol L -1 .Keywords: chitosan; copper(II); stripping analysis. INTRODUÇÃOO desenvolvimento de procedimentos analíticos que permitam determinar concentrações baixas de íons metálicos em águas naturais e/ou residuárias é de extremo interesse e vem sendo objeto de estudo recente em química analítica. Com o advento das técnicas eletroanalíticas, os sensores eletroquímicos ganharam um importante espaço nas diversas áreas de pesquisa 1,2 .O desenvolvimento e aplicação de eletrodos modificados (EM) 3-7 , tem tido crescente interesse nas áreas de ciências e tecnologia, com aplicação em diversos campos de pesquisa, tais como eletrocatálise, síntese eletroorgânica, conversão de energia solar e, principalmente, em eletroanálise e sensores químicos. A denominação de eletrodos quimicamente modificados foi sugerida por Murray et al. na década de 70 para definir eletrodos com espécies quimicamente ativas devidamente imobilizadas na superfície desses dispositivos 8 . O EM é construído adicionando-se espécies quimicamente ativas imobilizadas no substrato do eletrodo, com o objetivo de pré-estabelecer e controlar a natureza físico-química da interface eletrodo/solução. A modificação do eletrodo normalmente confere a este as características físico-quími-cas (reatividade, seletividade etc.) do modificador, possibilitando assim o desenvolvimento de dispositivos com resposta adequada para vários propósitos e aplicações. Nesse aspecto, são encontradas na literatura diversas revisões que descrevem as diferentes estratégias para construção de eletrodos modificados 3-9 .A introdução da pasta de carbono e suas primeiras aplicações estão relacionadas com o grupo de Adams 10 que estudou algumas características básicas e algumas aplicações para os eletrodos de pasta de carbono. No final da década de 70 surgiram vários trabalhos empregando modificações dos eletrodos, sendo o início dos anos 80 um marco na história dos eletrodos de pasta de carbono modificados, quando se desenvolveu um sensor modificado com dimetilglioxima para a determinação de íons Ni(II) 11 . Neste trabalho, verificou-se que o uso de um reagente seletivo clássico proporcionou aumento significativo da seletividade do eletrodo.A superfície dos eletrodos de pasta de carbono é muito complexa, com muitas po...

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Electrocatalytic oxidation of reduced nicotinamide coenzymes at gold and platinum electrode surfaces modified with a monolayer of pyrroloquinoline quinone. Effect of Ca2+ cations

Cited by 201 publications

References 55 publications

NADH Oxidation Using Carbonaceous Electrodes Modified with Dibenzo‐Dithia‐Diazapentacene

NADH Oxidation Using Carbonaceous Electrodes Modified with Dibenzo‐Dithia‐Diazapentacene

Electrochemistry of Pyrroloquinoline Quinone (PQQ) on Multi-Walled Carbon Nanotube-Modified Glassy Carbon Electrodes in Biological Buffers

Determinação voltamétrica por redissolução anódica de Cu(II) em águas residuárias empregando um eletrodo de pasta de carbono modificado com quitosana

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