Charge transfer at partially blocked surfaces

Amatore, Christian; Savéant, Jean‐Michel; Tessier, D.

doi:10.1016/s0022-0728(83)80055-2

Cited by 802 publications

(741 citation statements)

References 24 publications

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“…The CMM 27,28 considers that the electrode coverage is not complete in the early stages of growth of the multilayer and describes it as an array of circular areas that are uncovered by both PE and NPs and, therefore, more accessible to the electroactive species. [37][38][39][40][41][42][43] These uncovered areas may persist during the sequential assembly of the multilayer, although they are progressively reduced in area and number as more layers are added. These areas play a key role in the transport properties of the multilayer, even after they are completely covered, because the film is less dense in those regions where there were opened spots previously and the flux density of the electroactive species is higher.…”

Section: Theorymentioning

confidence: 99%

“…Mass transport in this model accounts for the possible defects present in the multilayer leading to nonlinear diffusion. [37][38][39][40][41][42][43] There is substantial experimental evidence on the existence of defects and preferential paths for diffusion at the first stages in the growth of PEMUs. 44,45 We also demonstrate here the existence of defects in the early and intermediate stages of the build-up process of PE/Au NP multilayers by means of the AFM technique, thus supporting the validity of the CMM.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Characterization of Polyelectrolyte/Gold Nanoparticle Multilayers Self-Assembled on Gold Electrodes

et al. 2005

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Polyelectrolyte/gold nanoparticle multilayers composed of poly(L-lysine) (pLys) and mercaptosuccinic acid (MSA) stabilized gold nanoparticles (Au NPs) were built up using the electrostatic layer-by-layer self-assembly technique upon a gold electrode modified with a first layer of MSA. The assemblies were characterized using UV-vis absorption spectroscopy, cyclic and square-wave voltammetry, electrochemical impedance spectroscopy, and atomic force microscopy. Charge transport through the multilayer was studied experimentally as well as theoretically by using two different redox pairs [Fe(CN) 6 ] 3-/4-and [Ru(NH 3 ) 6 ] 3+/2+ . This paper reports a large sensitivity to the charge of the outermost layer for the permeability of these assemblies to the probe ions. With the former redox pair, dramatic changes in the impedance response were obtained for thin multilayers each time a new layer was deposited. In the latter case, the multilayer behaves as a conductor exhibiting a strikingly lower impedance response, the electric current being enhanced as more layers are added for Au NP terminated multilayers. These results are interpreted quite satisfactorily by means of a capillary membrane model that encompasses the wide variety of behaviors observed. It is concluded that nonlinear slow diffusion through defects (pinholes) in the multilayer is the governing mechanism for the [Fe(CN) 6 ] 3-/4-species, whereas electron transfer through the Au NPs is the dominant mechanism in the case of the [Ru(NH 3 ) 6 ] 3+/2+ pair.

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Section: Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrochemical Characterization of Polyelectrolyte/Gold Nanoparticle Multilayers Self-Assembled on Gold Electrodes

et al. 2005

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“…Given the strong Au-S bond, the latter is the most likely to occur, forming the so-called ''collapsed sites'' and increasing the distance between the centers of the neighbouring pinholes. 30 6 ] 3À (PBS, pH 7.0). Note that saponin is used to block pinholes or non-specific sites on the Au-MEODA-MA prior to anti-MA antibody detection in TB serum.…”

Section: Sam Fabrication Xps and Afm Characterizationmentioning

confidence: 99%

Electron transfer dynamics across self-assembled N-(2-mercaptoethyl) octadecanamide/mycolic acid layers: impedimetric insights into the structural integrity and interaction with anti-mycolic acid antibodies

Ozoemena

Mathebula

Pillay

et al. 2010

Phys. Chem. Chem. Phys.

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The integrity and properties of mycolic acid (MA) antigens integrated into a self-assembled monolayer (SAM) of N-(2-mercaptoethyl)octadecanamide, (MEODA), on a gold electrode have been interrogated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). EIS data showed that Au-MEODA and Au-MEODA-MA behave as microelectrode arrays, with pinholes acting as the microelectrodes that permit electron transport between a redox-active probe in solution and the underlying gold surface. The average radii of the pinholes (r a ) and half the distance between the centers of the neighbouring pinholes (r b ), were estimated from EIS using the pore size model, and discussed. Anti-MA antibodies present in a tuberculosis (TB)-infected patient (co-infected with HIV) strongly interact with Au-MEODA-MA showing a rather compact and stable bio-complex structure that is virtually defect-free. The electrochemical impedimetric properties associated with the ability of the Au-MEODA-MA to discriminate between TB positive and negative human sera are also discussed. We prove that the Au-MEODA and Au-MEODA-MA electrodes, as well as the MA-anti-MA antibody interactions, are characterized with time-constant dispersion, typical of microstructures with grain/grain boundary phases. These crucial physico-electrochemical insights into the behaviour of surface-confined MA should provide a useful basis for the design and development of a potential impedimetric immunosensing platform for active tuberculosis.

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“…Under static conditions, an overlapping diffusion field results for both types of membrane under experimentally accessible conditions, hence the flux (current) to the overlapping ensemble is identical to that for macroelectrodes of the same geometric area, even though the fraction of exposed surface (1Ày) may tend to zero in the ensemble case. 27,28,51 By contrast, these models have not been extended to hydrodynamic systems, specifically where laminar flow in a channel configuration or a rotating disc system is used to augment mass-transport. 52 Instead, the behaviour of microelectrode arrays under hydrodynamic conditions has been interpreted in terms of ''limiting cases'' of the behaviour in static solution.…”

Section: Ion Transfer At the Modified L/l Interface: Mesoporous Matermentioning

confidence: 99%

Modifying the liquid/liquid interface: pores, particles and deposition

Dryfe

2006

Phys. Chem. Chem. Phys.

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Charge transfer at partially blocked surfaces

Cited by 802 publications

References 24 publications

Electrochemical Characterization of Polyelectrolyte/Gold Nanoparticle Multilayers Self-Assembled on Gold Electrodes

Electrochemical Characterization of Polyelectrolyte/Gold Nanoparticle Multilayers Self-Assembled on Gold Electrodes

Electron transfer dynamics across self-assembled N-(2-mercaptoethyl) octadecanamide/mycolic acid layers: impedimetric insights into the structural integrity and interaction with anti-mycolic acid antibodies

Modifying the liquid/liquid interface: pores, particles and deposition

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