Development of an amperometric assay for NH+4 based on a chemically modified screen-printed NADH sensor

Abass, A.K.; Hart, John P.; Cowell, David C.; Chappell, Alfred E.

doi:10.1016/s0003-2670(98)00368-7

Cited by 32 publications

(18 citation statements)

References 11 publications

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“…The determination of ammonium in the environmental samples employing enzymatic reactions has been reported previously [7,10]. The applications of diaphorase coupled with tetrazolium salts, which produce highly colored formazan dyes upon NADH oxidation, have been used as chromogenic reagents for quantification of NADH as detection signal [15].…”

Section: Optimization Of An Optical Assay For Ammonium Employing the mentioning

confidence: 99%

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An Optical Based Biosensor for the Determination of Ammonium in Aqueous Environment

Azmi¹,

Abdullah²,

Ahmad³

et al. 2012

AJAC

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A simple and rapid optical biosensor for the determination of ammonium was developed by immobilization of glutamate dehydrogenase (GLDH) and diaphorase (Dph) in chitosan film coated on a glass slide employing thiazolyl blue tetrazolium bromide (MTT) as a color indicator. The developed biosensor displays a purple color formation of formazan attributed to the unreacted NADH in the reaction system in the presence of ammonium. The color intensity was found to decrease proportionally with the increase of ammonium concentrations after 10 min exposure. The linearity of the biosensor towards ammonium was in the range of 16.8 -70 µM (R 2 = 0.9955) with detection limit of 11 µM. A good agreement (R 2 = 0.9984) with indothymol method was obtained in the measurement of fish pond water samples. The effect of potential interferences such as metals ion has also been evaluated.

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Section: Optimization Of An Optical Assay For Ammonium Employing the mentioning

confidence: 99%

“…These methods are time consuming and often require skill personnel to operate the sample preparation. An interesting alternative method for determination of dissolved ammonia involves the development of biosensors, which can offer simple, rapid, sensitive, specific and portable system [2,3,7].…”

Section: Introductionmentioning

confidence: 99%

An Optical Based Biosensor for the Determination of Ammonium in Aqueous Environment

Azmi¹,

Abdullah²,

Ahmad³

et al. 2012

AJAC

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“…In addition, mass production using screen-printing technology allows fabrication at low cost; the biosensors could therefore be used once and discarded without the inherent problems of contamination. The prototype amperometric biosensor [16] was based on the following enzymatic reaction [17] where GLDH represents glutamate dehydrogenase. The measurement of NH 4 + was again dependent on the detection of NADH by its electrocatalytic oxidation at the MB-SPCE.…”

Section: Ammoniamentioning

confidence: 99%

Recent developments towards disposable screen-printed biosensors incorporating a carbon ink modified with the redox mediotor. Meldola's Blue

Wedge¹,

Pemberton²,

Hart³

et al. 1999

Analusis

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Screen-printed carbon electrodes (SPCEs) can be mass-produced at low cost and are readily adaptable as base transducers for incorporation into disposable biosensors. As biological recognition elements, the NAD + -dependent dehydrogenase enzymes have wide ranging application for the determination of many analytes in biological samples. In order to achieve the desired selectivity, it has proved necessary to reduce the overpotential required to electrochemically regenerate the cofactor, NAD + , by incorporating redox mediators into the carbon ink prior to screenprinting. One such electrocatalyst, Meldola's Blue (MB), has been used successfully and has been combined with dehydrogenase enzymes for the determination of some important biological analytes, including lactate, alcohol and ammonia. These examples from our laboratory using MBmodified SPCEs will be reviewed in this article, together with a recent application to determine aspartate aminotransferase (AST) in serum.

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“…24 The redox behavior and efficient electrocatalytic properties of these organic dyes have been employed for the determination of different substrates such as H 2 O 2 , 25,26 alcohols, 27 lactate, [28][29][30] ammonia, 31 acid formic 32 and enzymes like aspartate aminotransferase 33 and horseradish peroxidase. 26 The optimization of the experimental conditions that leads to the best values of the reversibility of an electrochemical system requires the study of several variables, such as kind of electrode, pH of the solution, concentration of supporting electrolyte, scan rate, etc.…”

Section: Introductionmentioning

confidence: 99%

Cationic dyes immobilized on cellulose acetate surface modified with titanium dioxide: factorial design and an application as sensor for NADH

Hoffmann¹,

Dias²,

Benvenutti³

et al. 2007

J. Braz. Chem. Soc.

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As propriedades eletroquímicas dos corantes catiônicos, azul de meldola e azul de toluidina, imobilizados na superfície do acetato de celulose modificado com dióxido de titânio foram investigadas por voltametria cíclica. Os materiais sintetizados foram empregados como eletrodos de pasta de carbono. As propriedades mediadoras redox dos eletrodos modificados quimicamente com azul de meldola e azul de toluidina foram otimizadas utilizando um planejamento fatorial consistindo de dois níveis e quatro fatores com dois pseudo-pontos centrais (n=20 experimentos). A análise fatorial foi realizada para investigar as melhores condições de reversibilidade do processo redox tais como uma diminuição na separação entre os picos de potenciais anódico e catódico e razão de corrente próxima da unidade. Os fatores que apresentaram efeitos significantes na otimização global do sistema e que permitiram alcançar as melhores condições de reversibilidade de transferência de elétrons foram os fatores principais velocidade de varredura e tipo de eletrodo (azul de meldola ou azul de toluidina) além dos fatores de interação concentração do KCl × tipo de eletrodo (B×D) e a interação pH × [KCl] × velocidade de varredura (A×B×C). As melhores condições de reversibilidade eletroquímica obtidas foram: o eletrodo CA-TiO 2 -MB, KCl 1,0 mol L -1 como eletrólito suporte e velocidade de varredura de 10,0 mV s -1 . Adicionalmente, o eletrodo modificado CA-TiO 2 -MB foi testado como sensor amperométrico para a determinação de NADH com um limite de detecção de 0,1 µmol L -1 .The electrochemical properties of meldola blue and toluidine blue cationic dyes immobilized on cellulose acetate surface modified with titanium dioxide were investigated by cyclic voltammetry. The materials synthesized were employed as carbon paste electrodes. The redox mediator properties of the meldola blue and toluidine blue chemically modified electrodes were optimized using a factorial design, consisting of two levels and four factors with two pseudo-central points (n= 20 experiments). The factorial analysis was carried out by searching for better reversibility of the redox process, such as the lowest separation between anodic and cathodic potential peaks and a current ratio near unity. The factors that presented significant effects on the overall optimization of the system to achieve the best conditions of the reversibility of electron transfer were the main factors scan rate and type of electrode (meldola blue or toluidine blue), besides the interaction factors KCl concentration × type of electrode (B×D) and the pH × [KCl] concentration × scan rate (A×B×C) interaction. The best electrochemical reversibility conditions obtained were: using the CA-TiO 2 -MB electrode, 1.0 mol L -1 KCl as supporting electrolyte, at scan rate of 10.0 mV s -1 . Afterwards, the CA-TiO 2 -MB modified electrode was tested as an amperometric sensor for the determination of NADH, with a detection limit of 0.1 µmol L -1 .Keywords: meldola blue, toluidine blue, modified cellulose acetate, factorial desig...

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Development of an amperometric assay for NH+4 based on a chemically modified screen-printed NADH sensor

Cited by 32 publications

References 11 publications

An Optical Based Biosensor for the Determination of Ammonium in Aqueous Environment

An Optical Based Biosensor for the Determination of Ammonium in Aqueous Environment

Recent developments towards disposable screen-printed biosensors incorporating a carbon ink modified with the redox mediotor. Meldola's Blue

Cationic dyes immobilized on cellulose acetate surface modified with titanium dioxide: factorial design and an application as sensor for NADH

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