Studies on Self‐Assembled Alkanethiol Monolayers Formed at Applied Potential on Polycrystalline Gold Electrodes

Brett, Christopher M. A.; Kresak, Slavoj; Hianik, Tibor; Oliveira-Brett, Ana Maria

doi:10.1002/elan.200390069

Cited by 88 publications

(91 citation statements)

References 32 publications

(39 reference statements)

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“…It is interesting that is also a signicant increase in R ct , since it has been established that this charge transfer response is largely determined by redox reaction through pinhole defects in the SAM layer formed on multicrystalline electrode surfaces. [26][27][28] This suggests that the local enhanced pH change and hydrogel growth increases the observed charge transfer resistance through constricting the size, and/or blocking at least some, of these pinholes as a result of the creation of hydrogel anchor points to the underlying electrode, which is consistent with the previously observed adherence of the hydrogel. The nal sensing step again resulted in the expected signicant increase in R ct (without a change in R nl ), due to the formation of the more blocking PNA-DNA duplex SAM lm at the electrode surface.…”

supporting

confidence: 79%

Functionalised microscale nanoband edge electrode (MNEE) arrays: the systematic quantitative study of hydrogels grown on nanoelectrode biosensor arrays for enhanced sensing in biological media

et al. 2018

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Nanoelectrodes and nanoelectrode arrays show enhanced diffusion and greater faradaic current densities and signal-to-noise ratios compared to macro and microelectrodes, which can lead to enhanced sensing and detection. One example is the microsquare nanoband edge electrode (MNEE) array system, readily formed through microfabrication and whose quantitative response has been established electroanalytically. Hydrogels have been shown to have applications in drug delivery, tissue engineering, and antibiofouling; some also have the ability to be grown electrochemically. Here, we combine these two emerging technologies to demonstrate the principles of a hydrogel-coated nanoelectrode array biosensor that is resistant to biofouling. We first electrochemically grow and analyze hydrogels on MNEE arrays. The structure of these gels is shown by imaging to be electrochemically controllable, reproducible and structurally hierarchical. This structure is determined by the MNEE array diffusion fields, consistent with the established hydrogel formation reaction, and varies in structural scale from nano (early time, near electrode growth) to micro (for isolated elements in the array) to macro (when there is array overlap) with distance from the electrode, forming a hydrogel mesh of increasing density on progression from solution to electrode. There is also increased hydrogel structural density observed at electrode corners, attributable to enhanced diffusion. The resulting hydrogel structure can be formed on (and is firmly anchored to/ through) an established clinically relevant biosensing layer without compromising detection. It is also shown to be capable, through proof-of-principle model protein studies using bovine serum albumin (BSA), of preventing protein biofouling whilst

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confidence: 79%

Functionalised microscale nanoband edge electrode (MNEE) arrays: the systematic quantitative study of hydrogels grown on nanoelectrode biosensor arrays for enhanced sensing in biological media

et al. 2018

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“…51 Although anodic oxidative formation of thiolate SAM seems to be an interesting alternative for SAM formation, only a few investigations have been carried out, and details are not known. [52][53][54][55][56][57][58][59][60][61] Recently, we briefly reported that quantitative analysis of the reductive desorption of an electrodeposited thiolate layer provided us with useful information about the formation process of a SAM such as the time dependency of the adsorbed amount and the order of the SAM. 62 In this work, we studied in detail the anodic oxidative adsorption and cathodic reductive desorption of decanethiol layers on Au(111) electrodes in 0.1 M KOH ethanol solutions containing various concentrations of decanethiol.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Oxidative Formation and Reductive Desorption of a Self-Assembled Monolayer of Decanethiol on a Au(111) Surface in KOH Ethanol Solution

Sumi

Uosaki

2004

J. Phys. Chem. B

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Electrochemical oxidative adsorption and reductive desorption of a self-assembled monolayer (SAM) of decanethiol on a Au(111) single crystal electrode were examined in 0.1 M KOH ethanol solution containing various concentrations of decanethiol ranging from 1 µM to 1 mM. Anodic and cathodic current peaks corresponding to the adsorption and desorption of decanethiol, respectively, were observed in cyclic voltammograms of a Au(111) single crystal electrode obtained in 0.1 M KOH ethanol solution containing more than 10 µM of decanethiol. Positions of both peaks depended on the concentration of decanethiol, and they shifted negatively by ca. 0.057 V/decade with increase in decanethiol concentration. This result confirms that the adsorption and desorption of decanethiol is a one-electron process. The reductive charge, which consists of desorption charge and capacitive charge, increased when the sweep rate was decreased and the decanethiol concentration was increased and reached the saturated value of 103 ((5%) µC cm , which corresponds to the reductive charge of thiol SAM of full coverage with a ( 3 × 3)R30°structure. Potentiostatic SAM formation was also investigated by holding the potential at +0.1 V. The reductive charge, i.e., the coverage of the SAM, increased with time and reached the saturated value of 103 ((5%) µC cm -2 , corresponding to full coverage, after holding the potential at +0.1 V for a certain period of time. The time when the amount of adsorbed thiolate reached full coverage depended on the concentration of decanethiol. The higher the concentration was, the faster full coverage was reached. The desorption peak shifted negatively as the holding time at +0.1 V was increased even after the adsorbed amount had reached full coverage. These results suggest that the ordering of decanethiol SAMs requires a much longer time than the time required for full coverage adsorption. The position of the reductive desorption peak was independent of the thiol concentration if the electrode was kept at +0.1 V for long enough so that a highly ordered SAM was formed. The cathodic peak shifted negatively as the sweep rate was increased, showing that reductive desorption of the SAM was rather slow. The rate constant for the reductive desorption was determined from the potential dependent peak shift to be 0.24 s -1 , which is in good agreement with the value obtained for a SAM prepared without potential control, indicating that the quality of the electrochemically prepared SAM is as good as that of the SAM prepared nonelectrochemically.

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“…In the literature, many aspects related to the adsorption of thiols on gold are described [13,21,22] and cysteine is one of the most popular examples of this class of compounds [23 -25]. This small amino acid that contains a thiol group has been particularly used to modify electrode surfaces.…”

Section: Applicationmentioning

confidence: 99%

Disposable Gold Electrodes with Reproducible Area Using Recordable CDs and Toner Masks

et al. 2006

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The fabrication and characterization of very cheap disposable gold disk electrodes with reproducible area is reported. The innovation of the proposed procedure is the use of toner masks to define reproducible areas on uniform gold surfaces obtained from recordable compact disks (CD-R). Toner masks are drawn in a laser printer and heat transferred to gold surfaces, defining exactly the electrodes area. The electrochemical behavior of these disposable electrodes was investigated by cyclic voltammetry in Fe(CN) 6 4À solutions. The relative standard deviation for signals obtained from 10 different gold electrodes was below 1 %. The size of the disk electrodes can be easily controlled, as attested by voltammetric responses recorded by using electrodes with radii varying from 0.5 to 3.0 mm. The advantages of using this kind of electrode for analytical measurements of substances that strongly adsorb on the electrode surface such as cysteine are also addressed.

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Studies on Self‐Assembled Alkanethiol Monolayers Formed at Applied Potential on Polycrystalline Gold Electrodes

Cited by 88 publications

References 32 publications

Functionalised microscale nanoband edge electrode (MNEE) arrays: the systematic quantitative study of hydrogels grown on nanoelectrode biosensor arrays for enhanced sensing in biological media

Functionalised microscale nanoband edge electrode (MNEE) arrays: the systematic quantitative study of hydrogels grown on nanoelectrode biosensor arrays for enhanced sensing in biological media

Electrochemical Oxidative Formation and Reductive Desorption of a Self-Assembled Monolayer of Decanethiol on a Au(111) Surface in KOH Ethanol Solution

Disposable Gold Electrodes with Reproducible Area Using Recordable CDs and Toner Masks

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