Ellipsometric and Electrochemical Study of Dopamine Adsorbed on Gold Electrodes

and, Jyotiranjan Ota; Sustersic, M. G.

doi:10.1021/la991704t

Cited by 16 publications

(13 citation statements)

References 45 publications

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“…The optical indices of the substrate were obtained at open circuit in the aqueous electrolyte, from the ellipsometric parameters of the polished gold electrode. The resulting values were in good agreement with previously reported data [15,28,29].…”

Section: Methodssupporting

confidence: 92%

“…Experimental conditions were similar to those described in previous work [28,29]. The gold electrode was made by axially fitting a polycrystalline gold plaque (99.99% purity, 1.5 mm thick) into a Teflon sheath.…”

Section: Methodsmentioning

confidence: 99%

“…The real part of the refraction index of the film, n, the imaginary part of the refraction index or absorption coefficient, k, and the thickness, d, are calculated using the gradient technique [28,29].…”

Section: Calculationsmentioning

confidence: 99%

“…However, the single homogeneous film model is a good first approximation in the description of the interface, and these indices correspond to effective optical indices for the composite fibre/occluded electrolyte layer [28,29]. In the case of composite materials, the effective medium theory using either Maxwell Garnett or Bruggeman formalisms relates the optical constant of the polymeric fibre phase and that of the electrolyte with the volume fraction of the components providing the effective optical constants for the composite polymer/electrolyte.…”

Section: Calculationsmentioning

confidence: 99%

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Electrochromism and Swelling of Polypyrrole Membranes: An Electrochemical and Ellipsometric Study

Zerbino

Sustersic²,

Falivene³

et al. 2011

International Journal of Electrochemistry

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The growth of polypyrrole (Ppy) layers on gold electrodes in nearly neutral pH solutions is analysed using "in situ" voltametric and ellipsometric techniques. Different film structures are obtained depending on the potentiodynamic programme and the composition of the electrolyte. More compact dodecylsulphate-(DS) doped Ppy layers were grown at 1.2 V versus RHE than those obtained by applying a higher potential. The more compact layers correspond to the growth of an oxidised Ppy/DS layer that shows low pseudo capacity behaviour. After dipping, the doped Ppy/DS film in KCl solution-significant variations in optical indices and thickness are detected as a function of the applied potential. Higher electrochromism as well as decrease in film thickness after cathodisation is achieved. The optical indices and the thickness of the Ppy layer formed under different applied potential/time programmes are estimated.

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Section: Methodssupporting

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Section: Calculationsmentioning

confidence: 99%

Section: Calculationsmentioning

confidence: 99%

See 2 more Smart Citations

Electrochromism and Swelling of Polypyrrole Membranes: An Electrochemical and Ellipsometric Study

Zerbino

Sustersic²,

Falivene³

et al. 2011

International Journal of Electrochemistry

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“…1,2 However, the electrochemical detection of DA at the conventional electrodes has suffered from a high concentration of AA present in mammalian nerve and brain tissues because of close oxidation potentials and the reaction between AA and the oxidized form of DA. 3 In order to improve the selectivity and sensitivity, various modified electrodes, [4][5][6][7][8][9][10][11] especially based on self-assembly technology, 12 have been developed for determining DA.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Behavior of Dopamine and Ascorbic Acid at Osmium(II) Complex Cationic Monolayer Modified Gold Electrodes

Zhang

Jeon

2002

ANAL. SCI.

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IntroductionAs an important neurotransmitter in the mammalian central nervous system, DA has received much interest. 1,2 However, the electrochemical detection of DA at the conventional electrodes has suffered from a high concentration of AA present in mammalian nerve and brain tissues because of close oxidation potentials and the reaction between AA and the oxidized form of DA.3 In order to improve the selectivity and sensitivity, various modified electrodes, 4-11 especially based on self-assembly technology, 12 have been developed for determining DA. [13][14][15][16][17][18] Since DA and AA carry different charges in neutral solutions, negatively charged self-assembled monolayers of ω-mercapto carboxylic acids on gold electrodes were reported as a means to induce an electrochemical difference between DA and AA based on electrostatic interactions. 19 On the other hand, gold electrodes modified by positively charged self-assembled monolayers of 2,2′-dithiobisethaneamine and 6,6′-dithiobishexaneamine 20 and dinickel(II) (2,2′-bis(1,3,5,8,12-pentaazacyclotetradec-3-yl Experimental Chemicals and materials[Os(bpy)2(bpy-(CH2)13SH)](PF6)2 (bpy = 2,2′-bipyridine) was synthesized and characterized as reported. 28 Fresh phosphate buffer solutions (PBS) of DA (Sigma) and AA (Aldrich) were prepared before each measurement. PBS was prepared by mixing stock solutions of 0.2 M Na2HPO4 and 0.2 M NaH2PO4 and diluting with water. Triply distilled water was used in all runs. Preparation of an [Os(bpy)2(bpy (CH2)13SH)] 2+ /Au electrode and an [Os(bpy)2(bpy-(CH2)13SH)] 2+ + CH3(CH2)11SH/Au electrodeA polycrystalline gold disc electrode (0.2 cm 2 ) was pretreated in a piranha solution for 15 min and sonicated for several minutes. It was then washed with water and ethanol. After being dried with a stream of high-purity nitrogen gas, the electrode was soaked into a methanol solution of 1 mM [Os(bpy)2(bpy-(CH2)13SH)] 2+ for 24 h. Thus, a gold electrode modified with [Os(bpy)2(bpy-(CH2)13SH)] 2+ self-assembled monolayer ([Os(bpy)2(bpy-(CH2)13SH)] 2+ /Au) was prepared. It was used after being thoroughly rinsed by water and ethanol and dried with nitrogen gas. The [Os(bpy)2(bpy-(CH2)13SH)] 2+ + CH3(CH2)11SH/Au electrode was prepared by soaking the gold electrode into a methanol solution consisting of 1 mM [Os-(bpy)2(bpy-(CH2)13SH)] 2+ and 0.5 mM CH3(CH2)11SH for 24 h. Apparatus and proceduresElectrochemical experiments were carried out using a BAS 100B/W electrochemical analyzer. The electrooxidation of dopamine (DA) and ascorbic acid (AA) was studied using gold electrodes modified by a cationic self-assembled monolayer of [Os(bpy)2(bpy-(CH2)13SH)] 2+ by cyclic voltammetry.At an [Os(bpy)2(bpy-(CH2)13SH)] 2+ /Au electrode, the oxidation peak of DA shifted to a much more positive potential as compared with that of a bare gold electrode, while the oxidation peak potential of AA showed a slightly negative shift due to their different electrostatic interactions with the cationic monolayer. Thus, a sufficient potential difference was achieved ...

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Deviceless decoupled electrochemical detection of catecholamines in capillary electrophoresis using gold microband array electrodes

2002

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Samples containing microM concentrations of dopamine, (+/-)-isoproterenol, para-aminophenol and chlorogenic acid have been separated by capillary electrophoresis (CE) and detected using end-column amperometric detection based on a novel decoupling method. The present decoupling approach involves the use of an electrochemical detector chip containing an array of microband electrodes where the working and reference electrodes are positioned only 10 microm from each other. The short distance between the working and reference electrodes ensures that both electrodes are very similarly affected by the presence of the CE electric field. With this method, no shift in the detection potential was seen when the CE high voltage was applied. This eliminated the need for a reoptimization of the detection potential to compensate for the influence of the separation voltage on the detection. It is also demonstrated that catecholamines can be detected using gold microband electrodes by careful adjustment of the detection potential to avoid the formation of gold oxide. Such careful adjustments of the detection potential are straightforward using the present decoupling method.

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Ellipsometric and Electrochemical Study of Dopamine Adsorbed on Gold Electrodes

Cited by 16 publications

References 45 publications

Electrochromism and Swelling of Polypyrrole Membranes: An Electrochemical and Ellipsometric Study

Electrochromism and Swelling of Polypyrrole Membranes: An Electrochemical and Ellipsometric Study

Electrochemical Behavior of Dopamine and Ascorbic Acid at Osmium(II) Complex Cationic Monolayer Modified Gold Electrodes

Deviceless decoupled electrochemical detection of catecholamines in capillary electrophoresis using gold microband array electrodes

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