Electrochemical study of gold electrodes with anodic oxide films—I. Formation and reduction behaviour of anodic oxides on gold

Oesch, U.; Janata, Jiřı́

doi:10.1016/0013-4686(83)85011-7

Cited by 235 publications

(164 citation statements)

References 28 publications

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“…The studies used a 1.6 mm diameter polycrystalline gold working electrode (WE), a platinum wire counter electrode, and a Ag/AgCl/3M NaCl reference electrode. The working electrode was mechanically and electrochemically polished as previously described (42,43), and its roughness factor r (r ϭ true area/geometric area; r Ն 1) was measured from the double layer capacitance (42,43). Values of r ranged from 1.39 to 1.69, with an average of 1.56 Ϯ 0.09, and were used to correct probe and target coverages.…”

Section: Methodsmentioning

confidence: 99%

DNA surface hybridization regimes

Gong

Levicky²

2008

Proc. Natl. Acad. Sci. U.S.A.

218

282

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Surface hybridization reactions, in which sequence-specific recognition occurs between immobilized and solution nucleic acids, are routinely carried out to quantify and interpret genomic information. Although hybridization is fairly well understood in bulk solution, the greater complexity of an interfacial environment presents new challenges to a fundamental understanding, and hence application, of these assays. At a surface, molecular interactions are amplified by the two-dimensional nature of the immobilized layer, which focuses the nucleic acid charge and concentration to levels not encountered in solution, and which impacts the hybridization behavior in unique ways. This study finds that, at low ionic strengths, an electrostatic balance between the concentration of immobilized oligonucleotide charge and solution ionic strength governs the onset of hybridization. As ionic strength increases, the importance of electrostatics diminishes and the hybridization behavior becomes more complex. Suppression of hybridization affinity constants relative to solution values, and their weakened dependence on the concentration of DNA counterions, indicate that the immobilized strands form complexes that compete with hybridization to analyte strands. Moreover, an unusual regime is observed in which the surface coverage of immobilized oligonucleotides does not significantly influence the hybridization behavior, despite physical closeness and hence compulsory interactions between sites. These results are interpreted and summarized in a diagram of hybridization regimes that maps specific behaviors to experimental ranges of ionic strength and probe coverage.biosensor ͉ ferrocene ͉ ionic strength ͉ microarray ͉ probe coverage S olid-phase or ''surface'' hybridization is the foundation of modern microarray and biosensing technologies widely used in applied genomics for genotyping, drug discovery, gene expression profiling, and related applications based on measurement of genomic information (1, 2). These tools function through detection of interactions between nucleic acids immobilized on a solid support, or ''probes,'' with analyte ''target'' nucleic acids present in solution. Binding, or hybridization, between probes and targets to form an immobilized duplex takes place based on the degree of complementarity between the probe and target base sequences. The tremendous growth in applications of surface hybridization has been mirrorred by increased emphasis on experimental and fundamental aspects of the assays that directly impact measurement and interpretation of data (3, 4).As summarized in several recent reviews (5-8), physical studies under simplified experimental conditions have begun to unravel the rich phenomenology that occurs in diagnostic assays. Applications typically operate away from equilibrium and are faced with a highly diverse pool of target sequences competing for the probe sites. A variety of aids to enhance hybridization performance is used, including surfactants and blocking agents to control nonspecific adsorp...

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Section: Methodsmentioning

confidence: 99%

DNA surface hybridization regimes

Gong

Levicky²

2008

Proc. Natl. Acad. Sci. U.S.A.

218

282

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“…The real surface area of AuNS was calculated for 50 mmol L -1 HClO4 in the potential range of 0.3 to 1.5 V with a scan rate of 0.05 V s -1 , and determined by an oxide desorption charge of 386 μC cm -2 through the reductive charge of the gold oxide monolayer to calculate the roughness factor. 29 …”

Section: Auns Electrodepositionmentioning

confidence: 99%

Effect of the Chain Length of a Modified Layer and Surface Roughness of an Electrode on Impedimetric Immunosensors

Lin

2017

ANAL. SCI.

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An ultrasensitive label-free impedimetric immunosensor is constructed by modifying a 3-mercaptoproponic acid (MPA) monolayer on highly rough gold nanostructure (AuNS)-electrodeposited screen printed carbon electrodes (SPCEs) for the detection of small molecular weight drugs (SMWDs), such as salbutamol (SAL). The SPCEs preoxidized in a 0.1 M H2SO4 solution (called po-SPCEH2SO4) are electrodeposited with the AuNS to increase the roughness factor to 23.64 ± 1.76, larger than the AuNS/po-SPCENaOH or the AuNS/po-SPCEPBS. Furthermore, the MPA modified layer as a link for the anti-SAL immobilization to give the immunosensors an impedimetric signal-to-noise ratio larger than the 11-mercaptoundecanoic acid-and 16-mercaptohexadecanoic acid-modified layer, due to the lower interfacial impedance of the MPA monolayer. The MPA/AuNS/po-SPCEH2SO4-based immunosensors have a wide linear range of 1 fg mL -1 to 1 ng mL -1 and a limit of detection of 0.6 fg mL -1 . Moreover, the immunosensors can practically quantify the SAL concentrations in 1000 times-diluted serum samples with good recovery.

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“…23,24 The area illuminated by the laser can be derived by multiplying the area of the laser spot with the roughness factor of the electrode. The focus of the laser at 514 nm using a 20Â objective has been determined previously to be 2 mm 2,5 resulting in an illuminated area of A 0 = 18.1 mm 2 .…”

Section: à2mentioning

confidence: 99%

Calculating average surface enhancement factors of randomly nanostructured electrodes by a combination of SERS and impedance spectroscopy

Kozuch

Petrusch

Gkogkou

et al. 2015

Phys. Chem. Chem. Phys.

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a Polyhedron Ag nanostructures were created on top of a polished Au electrode via step-wise electrodeposition and tested as substrates for SERS spectroscopy. Average Raman enhancement factors were derived by combining SERS measurements with electrochemical impedance spectroscopy (EIS), which is able to determine the electroactive surface area of a randomly nanostructured surface. Depending on the deposition step an alternating increase and decrease of surface area was observed while the SERS intensity showed a clear maximum for the first deposition cycle. SEM pictures reveal the formation of Ag polyhedrons that are randomly dispersed on the Au surface. Furthermore the presence of a sub nanostructure on top of the polyhedron after the first deposition cycle is observed which becomes smoother after subsequent deposition cycles. Correlating the SEM pictures with SERS and EIS measurements it is concluded that the coral-like sub nanostructure is dominating the enhancement factor while the polyhedron structure itself only plays a minor role for electromagnetic field enhancement.

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Electrochemical study of gold electrodes with anodic oxide films—I. Formation and reduction behaviour of anodic oxides on gold

Cited by 235 publications

References 28 publications

DNA surface hybridization regimes

DNA surface hybridization regimes

Effect of the Chain Length of a Modified Layer and Surface Roughness of an Electrode on Impedimetric Immunosensors

Calculating average surface enhancement factors of randomly nanostructured electrodes by a combination of SERS and impedance spectroscopy

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