Frequency response analysis of potential-modulated orientation changes of a DNA self assembled layer using spatially resolved fluorescence measurements.

Casanova-Moreno, Jannu; Bizzotto, Dan

doi:10.1016/j.electacta.2014.09.037

Cited by 13 publications

(19 citation statements)

References 63 publications

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“…The experimental EC-FCLSM setup was already described in previous reports. 12 , 22 Briefly, the electrochemical cell is placed above the objective of an inverted fluorescence confocal microscope (Scheme S1 † ). The working electrode is positioned in front of the objective, and is separated from the bottom of the electrochemical cell by a few millimetres.…”

Section: Resultsmentioning

confidence: 99%

A snapshot of the electrochemical reaction layer by using 3 dimensionally resolved fluorescence mapping

et al. 2018

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Section: Resultsmentioning

confidence: 99%

A snapshot of the electrochemical reaction layer by using 3 dimensionally resolved fluorescence mapping

et al. 2018

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“…The fluorophore in these DNA SAMs may be as far as 10 nm away from the gold surface and therefore not efficiently quenched. This incomplete quenching is useful for evaluating the DNA SAM coverage uniformity as well as for studying the DNA orientation change induced by the charge on the electrode surface. ,− The potentials used will be restricted to values more positive than the reductive desorption potential of a DNA/MCH SAM from the gold surface which is around −0.80 V/SCE (shown in Figure S7), similar to MUA or MCH SAMs (Figure ).…”

Section: Resultsmentioning

confidence: 99%

“…After these potential/hold treatments, a potential-step cycle was performed which showed only a small repeatable increase in fluorescence at negative potentials (Figure b). This small increase in fluorescence is due to the reversible electrostatic repulsion of the negatively charged DNA strand ,,− from a negatively charged surface. From this series of measurements, the as-prepared surface contains a significant amount of DNA which was removed at potentials more positive than the reductive desorption.…”

Section: Resultsmentioning

confidence: 99%

Measuring and Remediating Nonspecific Modifications of Gold Surfaces Using a Coupled in Situ Electrochemical Fluorescence Microscopic Methodology

Yang

Triffaux

et al. 2016

Anal. Chem.

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In surface-based biosensors, the nonspecific or undesired adsorption of the probe is an important characteristic that is typically difficult to measure and therefore to control or eliminate. A methodology for measuring and then minimizing or eliminating this problem on gold surfaces, readily applicable to many common surface modifications is presented. Combining electrochemical perturbation and fluorescence microscopy, we show that the potential at which the adsorbed species is removed can be used as an estimate of the strength of the adsorbate-surface interaction. This desorption potential can be easily measured through an increase in fluorescence intensity as the potential is manipulated. Furthermore, this method can be used to evaluate strategies for preventing or removing nonspecific adsorption. This is demonstrated for a wide variety of surface modifications, from strongly chemisorbed monolayers such as thiol self-assembled monolayers (SAMs) to physisorbed monolayers as well as for complex surface structures like peptide and DNA mixed-component SAMs. The use of a coadsorption strategy or small magnitude potential-step cycles was shown to significantly decrease the amount of nonspecifically or noncovalently bound probe, creating better defined surfaces.

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“…Fluorescence detection is another option to enhance the sensitivity of a potential-modulated ER measurement. Potential-modulated fluorescence (PMF) in a total internal reflection geometry has been used to study a variety of molecular processes near/at the interface between two immiscible liquids, including adsorption, complex formation, ion transfer, and the orientation of adsorbates. ,− Potential-modulated epifluorescence imaging has been used to measure potential-dependent switching of the orientation of DNA tethered to gold electrodes. , …”

Section: Introductionmentioning

confidence: 99%

“…15,25−29 Potential-modulated epifluorescence imaging has been used to measure potential-dependent switching of the orientation of DNA tethered to gold electrodes. 30,31 Here, we present the first demonstration of PM-TIRF for determining the ET kinetics at an organic/electrode interface, which is composed of a submonolayer of perylene diimide (PDI) functionalized with a p-phenylene phosphonic acid (phenyl-PA; Figure 1) adsorbed to indium−tin oxide (ITO).…”

Section: ■ Introductionmentioning

confidence: 99%

Potential-Modulated Total Internal Reflection Fluorescence for Measurement of the Electron Transfer Kinetics of Submonolayers on Optically Transparent Electrodes

et al. 2020

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An electroreflectance method to determine the electron transfer rate constant of a film of redox-active chromophores immobilized on an optically transparent electrode when the surface coverage of the film is very low (<0.1 monolayer) is described herein. The method, potential-modulated total internal reflection fluorescence (PM-TIRF) spectroscopy, is a fluorescence version of potential-modulated attenuated total reflection (PM-ATR) spectroscopy that is applicable when the immobilized chromophores are luminescent. The method was tested using perylene diimide (PDI) molecules functionalized with p-phenylene phosphonic acid (PA) moieties that bind strongly to indium−tin oxide (ITO). Conditions to prepare PDI-phenyl-PA films that exhibit absorbance and fluorescence spectra characteristic of monomeric (i.e., nonaggregated) molecules were identified; the electrochemical surface coverage was approximately 0.03 monolayer. The tilt angle of the long axis of the PDI molecular plane is 58°r elative to the ITO surface normal, 25°greater than the tilt angle of aggregated PDI-phenyl-PA films, which have a surface coverage of approximately one monolayer. The more in-plane orientation of monomeric films is likely due to the absence of cofacial π−π interactions present in aggregated films and possibly a difference in PA-ITO binding modes. The electron transfer rate constant (k s,opt ) of monomeric PDI-phenyl-PA films was determined using PM-TIRF and compared with PM-ATR results obtained for aggregated films. For PDI monomers, k s,opt = 3.8 × 10 3 s −1 , which is about 3.7-fold less than k s,opt for aggregated films. The slower kinetics are attributed to the absence of electron self-exchange between monomeric PDI molecules. Differences in the electroactivity of the binding sites on the ITO electrode surface also may play a role. This is the first demonstration of PM-TIRF for determining electron transfer rate constants at an electrode/organic film interface.

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Frequency response analysis of potential-modulated orientation changes of a DNA self assembled layer using spatially resolved fluorescence measurements.

Cited by 13 publications

References 63 publications

A snapshot of the electrochemical reaction layer by using 3 dimensionally resolved fluorescence mapping

A snapshot of the electrochemical reaction layer by using 3 dimensionally resolved fluorescence mapping

Measuring and Remediating Nonspecific Modifications of Gold Surfaces Using a Coupled in Situ Electrochemical Fluorescence Microscopic Methodology

Potential-Modulated Total Internal Reflection Fluorescence for Measurement of the Electron Transfer Kinetics of Submonolayers on Optically Transparent Electrodes

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