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Allen J. Bard - One of the best experts on this subject based on the ideXlab platform.
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Scanning Electrochemical Microscopy.
Annual review of analytical chemistry (Palo Alto Calif.), 2020Co-Authors: Shigeru Amemiya, Michael V Mirkin, Allen J. Bard, Patrick R UnwinAbstract:This review describes work done in Scanning Electrochemical Microscopy (SECM) since 2000 with an emphasis on new applications and important trends, such as nanometer-sized tips. SECM has been adapted to investigate charge transport across liquid/liquid interfaces and to probe charge transport in thin films and membranes. It has been used in biological systems like single cells to study ion transport in channels, as well as cellular and enzyme activity. It is also a powerful and useful tool for the evaluation of the electrocatalytic activities of different materials for useful reactions, such as oxygen reduction and hydrogen oxidation. SECM has also been used as an Electrochemical tool for studies of the local properties and reactivity of a wide variety of materials, including metals, insulators, and semiconductors. Finally, SECM has been combined with several other nonElectrochemical techniques, such as atomic force Microscopy, to enhance and complement the information available from SECM alone.
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Study of the EC' Mechanism by Scanning Electrochemical Microscopy (SECM)
ECS Transactions, 2019Co-Authors: Rob Calhoun, Allen J. BardAbstract:Scanning Electrochemical Microscopy (SECM) experiments were undertaken to study the EC’mechanism, e.g. where a product of the electrode reaction reacts to regenerate the starting material. Digital simulations of the two dimensional SECM were carried out and the results tested with the known EC’ system of Fe(CN)6 / cysteine for validation. The results were then used in SECM experiments with Ru(phen)2dppz, a known DNA intercalator, to study the instability of the oxidized form in the absence and presence of DNA.
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nanometer scale Scanning Electrochemical Microscopy instrumentation
Analytical Chemistry, 2016Co-Authors: Christophe Renault, Nikoloz Nioradze, Netzahualcoyotl Arroyocurras, Kevin C Leonard, Allen J. BardAbstract:We report the crucial components required to perform Scanning Electrochemical Microscopy (SECM) with nanometer-scale resolution. The construction and modification of the software and hardware instrumentation for nanoscale SECM are explicitly explained including (1) the LabVIEW code that synchronizes the SECM tip movement with the Electrochemical response, (2) the construction of an isothermal chamber to stabilize the nanometer scale gap between the tip and substrate, (3) the modification of a commercial bipotentiostat to avoid Electrochemical tip damage during SECM experiments, and (4) the construction of an SECM stage to avoid artifacts in SECM images. These findings enabled us to successfully build a nanoscale SECM, which can be utilized to map the electrocatalytic activity of individual nanoparticles in a typical ensemble sample and study the structure/reactivity relationship of single nanostructures.
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Study of the catalytic following reaction by Scanning Electrochemical Microscopy (SECM)
Journal of The Electrochemical Society, 2012Co-Authors: R. L. Calhoun, Allen J. BardAbstract:Scanning Electrochemical Microscopy (SECM) experiments were undertaken to study the EC′mechanism, e.g. where a product of the electrode reaction reacts to regenerate the starting material. Digital simulations of the two dimensional SECM were carried out and the results tested with the known EC′ system of Fe(CN)64−/cysteine for validation. The results were then used in SECM experiments with Ru(phen)2dppz2+, a known DNA intercalator, to study the instability of the oxidized form in the absence and presence of DNA. © 2012 The Electrochemical Society. [DOI: 10.1149/2.056203jes] All rights reserved.
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screening of photocatalysts by Scanning Electrochemical Microscopy
Analytical Chemistry, 2008Co-Authors: Heechang Ye, Allen J. BardAbstract:A method for rapid screening of photocatalysts employing a form of Scanning Electrochemical Microscopy (SECM) is described. A piezoelectric dispenser was used to deposit arrays composed of ∼300-μm-size photocatalyst spots with different compositions onto conducting glass, fluorine-doped tin oxide substrate. The Scanning tip of the SECM was replaced by a fiber optic connected to a xenon lamp and was rapidly scanned over the array. In this arrangement, the photocatalytic performance of the spots was evaluated by measuring the photocurrent at the substrate of the array. A fiber optic with a ring electrode can also be used to Electrochemically detect products of the photoreaction. Several iron oxide-based bimetallic oxide combinations were found to exhibit enhanced photocatalytic activity, when compared to pure α-Fe2O3. These combinations included iron−palladium, iron−europium, and iron−rubidium in specific ratios. A trimetallic bismuth−vanadium−zinc oxide combination was also found to show a higher photocurr...
Hubert H Girault - One of the best experts on this subject based on the ideXlab platform.
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Scanning Electrochemical Microscopy for Bioimaging
Encyclopedia of Interfacial Chemistry, 2020Co-Authors: Alexandra Bondarenko, Andreas Lesch, Hubert H GiraultAbstract:Scanning Electrochemical Microscopy (SECM) is a Scanning probe technique where typically micro- or nanoelectrodes are translated in close proximity to a specimen immersed in an electrolyte solution. The flux of redox active species between the SECM probe and the sample can be used to map local surface reactivity, to record the sample topography, or to manipulate the microenvironment of surfaces for micropatterning. Because SECM can be used in phosphate-buffered solutions with probes acting in contact-less or soft-contact mode, the technique is very attractive for the characterization of biological samples. Compared to microscopic techniques, the advantages of SECM include that the capability of extracting Electrochemical information in samples and avoiding potential optical interferences, e.g., from sample color-background.
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microfluidic push pull probe for Scanning Electrochemical Microscopy
Analytical Chemistry, 2011Co-Authors: Dmitry Momotenko, Fernando Cortessalazar, Andreas Lesch, Gunther Wittstock, Hubert H GiraultAbstract:This paper presents a microfluidic push–pull probe for Scanning Electrochemical Microscopy (SECM) consisting of a working microelectrode, an integrated counter/reference electrode and two microchannels for pushing and pulling an electrolyte solution to and away from a substrate. With such a configuration, a droplet of a permanently renewed redox mediator solution is maintained just at the probe tip to carry out SECM measurements on initially dry substrates or in microenvironments. For SECM imaging purposes, the probe fabricated in a soft polymer material is used in a contact regime. SECM images of various gold-on-glass samples demonstrate the proof-of-concept of a push–pull probe for local surface activity characterization with high spatial resolution even on vertically oriented substrates. Finite element computations were performed to guide the improvement of the probe sensitivity.
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seeing big with Scanning Electrochemical Microscopy
Analytical Chemistry, 2011Co-Authors: Fernando Cortessalazar, Hubert H Girault, Dmitry Momotenko, Andreas Lesch, Gunther WittstockAbstract:Specialized microelectrode probes fabricated in a soft polymer film now make it possible to use Scanning Electrochemical Microscopy to image the reactivity of large, corrugated, tilted, and dry surfaces. (To listen to a podcast about this Feature, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html.)
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Adsorbed protein detection by Scanning Electrochemical Microscopy
Journal of Electroanalytical Chemistry, 2009Co-Authors: Fernando Cortés-salazar, Fei Li, Jean-marc Busnel, Hubert H GiraultAbstract:A Scanning Electrochemical Microscopy (SECM) protein detection methodology has been developed based on the tagging of free cysteines and other nucleophiles in proteins and peptides by benzoquinone. The tagged proteins are detected by the mediated reduction of benzoquinone with a redox species produced Electrochemically at the SECM tip. After careful optimization, a sensitivity in the low ng mm 2 range was reached for bovine serum albumin. One of the major advantages of the present technique is that the selectivity of the protein tagging can be tuned by changing the pH of the reaction media. Depending on the requirements, cysteine selective or general detection can therefore be achieved with a high sensitivity. As a proof of concept, this technique was applied to the detection of protein spots and to the imaging of human fingerprints and further compared to the actual SECM state-of-art approach.
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Soft stylus probes for Scanning Electrochemical Microscopy.
Analytical Chemistry, 2009Co-Authors: Fernando Cortés-salazar, Gunther Wittstock, Fei Li, Jean-marc Busnel, Markus Träuble, Anne-laure Gassner, Mohamad Hojeij, Hubert H GiraultAbstract:A soft stylus microelectrode probe has been developed to carry out Scanning Electrochemical Microscopy (SECM) of rough, tilted, and large substrates in contact mode. It is fabricated by first ablating a microchannel in a polyethylene terephthalate thin film and filling it with a conductive carbon ink. After curing the carbon track and lamination with a polymer film, the V-shaped stylus was cut thereby forming a probe, with the cross section of the carbon track at the tip being exposed either by UV-photoablation machining or by blade cutting followed by polishing to produce a crescent moon-shaped carbon microelectrode. The probe properties have been assessed by cyclic voltammetry, approach curves, and line scans over Electrochemically active and inactive substrates of different roughness. The influence of probe bending on contact mode imaging was then characterized using simple patterns. Boundary element method simulations were employed to rationalize the distance-dependent Electrochemical response of the ...
Gunther Wittstock - One of the best experts on this subject based on the ideXlab platform.
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Quantitative characterization of shear force regulation for Scanning Electrochemical Microscopy
Comptes Rendus Chimie, 2012Co-Authors: Ushula M. Tefashe, Gunther WittstockAbstract:Abstract The quest for higher spatial resolution in Scanning Electrochemical Microscopy (SECM) calls for the application of smaller probe electrodes. When electrodes are to be used in the feedback mode, smaller electrodes require higher intrinsic kinetics at the sample. The fabrication of nanoelectrodes, as well as their use as SECM probes at constant distance, are reported. The properties of shear force regulation system are characterized quantitatively. Simultaneous topography and reactivity imaging were demonstrated using gold microstructures on a glass substrate.
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microfluidic push pull probe for Scanning Electrochemical Microscopy
Analytical Chemistry, 2011Co-Authors: Dmitry Momotenko, Fernando Cortessalazar, Andreas Lesch, Gunther Wittstock, Hubert H GiraultAbstract:This paper presents a microfluidic push–pull probe for Scanning Electrochemical Microscopy (SECM) consisting of a working microelectrode, an integrated counter/reference electrode and two microchannels for pushing and pulling an electrolyte solution to and away from a substrate. With such a configuration, a droplet of a permanently renewed redox mediator solution is maintained just at the probe tip to carry out SECM measurements on initially dry substrates or in microenvironments. For SECM imaging purposes, the probe fabricated in a soft polymer material is used in a contact regime. SECM images of various gold-on-glass samples demonstrate the proof-of-concept of a push–pull probe for local surface activity characterization with high spatial resolution even on vertically oriented substrates. Finite element computations were performed to guide the improvement of the probe sensitivity.
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seeing big with Scanning Electrochemical Microscopy
Analytical Chemistry, 2011Co-Authors: Fernando Cortessalazar, Hubert H Girault, Dmitry Momotenko, Andreas Lesch, Gunther WittstockAbstract:Specialized microelectrode probes fabricated in a soft polymer film now make it possible to use Scanning Electrochemical Microscopy to image the reactivity of large, corrugated, tilted, and dry surfaces. (To listen to a podcast about this Feature, please go to the Analytical Chemistry multimedia page at pubs.acs.org/page/ancham/audio/index.html.)
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Scanning Electrochemical Microscopy activity mapping of electrodes modified with laccase encapsulated in sol-gel processed matrix.
Bioelectrochemistry, 2010Co-Authors: Wojciech Nogala, Gunther Wittstock, Katarzyna Szot, Malte Burchardt, Martin Jönsson-niedziolka, Jerzy Rogalski, Marcin OpalloAbstract:Abstract Electrodes modified with sol–gel encapsulated laccase (isolated from Cerrena unicolor) exhibiting mediated or mediatorless bioelectrocatalytic dioxygen reduction activity were inspected using confocal laser Scanning Microscopy, atomic force Microscopy and Scanning Electrochemical Microscopy. Potential-driven leaching of the redox mediator 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) from carbon ceramic electrodes covered by hydrophilic silicate-encapsulated laccase was detected during electrocatalytic action. Strongly non-homogeneous lateral distribution of the activity towards dioxygen reduction was found by redox competition mode of Scanning Electrochemical Microscopy using a similar electrode with syringaldazine as redox mediator. Hydrogen peroxide formation at these electrodes is detected at potentials lower than 0.05 V. It is ascribed to the Electrochemical oxygen reduction at the carbon material while laccase-catalyzed oxygen reduction occurs below 0.35 V without hydrogen peroxide formation. The Scanning Electrochemical Microscopy images of electrodes consisting of single-walled carbon nanotubes non-covalently modified with pyrenesulfonate and laccase encapsulated in a sol–gel processed silicate film confirm direct electron transfer electrocatalysis in redox competition mode experiments and show that the enzyme is evenly distributed in the composite film. In conclusion Scanning Electrochemical Microscopy proved to be useful for mapping of enzyme activity on different materials.
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Soft stylus probes for Scanning Electrochemical Microscopy.
Analytical Chemistry, 2009Co-Authors: Fernando Cortés-salazar, Gunther Wittstock, Fei Li, Jean-marc Busnel, Markus Träuble, Anne-laure Gassner, Mohamad Hojeij, Hubert H GiraultAbstract:A soft stylus microelectrode probe has been developed to carry out Scanning Electrochemical Microscopy (SECM) of rough, tilted, and large substrates in contact mode. It is fabricated by first ablating a microchannel in a polyethylene terephthalate thin film and filling it with a conductive carbon ink. After curing the carbon track and lamination with a polymer film, the V-shaped stylus was cut thereby forming a probe, with the cross section of the carbon track at the tip being exposed either by UV-photoablation machining or by blade cutting followed by polishing to produce a crescent moon-shaped carbon microelectrode. The probe properties have been assessed by cyclic voltammetry, approach curves, and line scans over Electrochemically active and inactive substrates of different roughness. The influence of probe bending on contact mode imaging was then characterized using simple patterns. Boundary element method simulations were employed to rationalize the distance-dependent Electrochemical response of the ...
Encarnación Lorenzo - One of the best experts on this subject based on the ideXlab platform.
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Imaging resolution of biocatalytic activity using nanoscale Scanning Electrochemical Microscopy
Nano Research, 2018Co-Authors: Jose Maria Abad, Álvaro Y. Tesio, Félix Pariente, Emiliano Martínez-periñán, Encarnación LorenzoAbstract:Scanning Electrochemical Microscopy represents a powerful tool for electro(chemical) characterization of surfaces, but its applicability has been limited in most cases at microscale spatial resolution, and the greatest challenge has been the scaling down to the nanoscale for fabrication and the use of nanometer-sized tips. Here, Pt nanoelectrodes with nanometer electroactive area were fabricated and employed for imaging a distribution of gold nanoparticles (AuNPs) and bioelectrocatalytic activity of a redox-active enzyme immobilized on gold surfaces.
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Patterning Gold Nanoparticle Using Scanning Electrochemical Microscopy
Journal of Physical Chemistry C, 2013Co-Authors: Jose Maria Abad, Álvaro Y. Tesio, Félix Pariente, Encarnación LorenzoAbstract:Patterned arrays of gold nanoparticles (AuNPs) are prepared using Scanning Electrochemical Microscopy by Electrochemical reduction of a gold salt at a platinum ultramicroelectrode positioned on top of an unbiased gold surface, modified with a biphenyl dithiol self-assembled monolayer (SAM). The synthesized AuNPs are chemisorbed on the thiolated SAM, and by moving the microelectrode in a lateral direction across the surface while applying a reduction potential, particle-like lines are generated.
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Patterning Gold Nanoparticle Using Scanning Electrochemical Microscopy
The Journal of Physical Chemistry C, 2013Co-Authors: Jose Maria Abad, Álvaro Y. Tesio, Félix Pariente, Encarnación LorenzoAbstract:Patterned arrays of gold nanoparticles (AuNPs) are prepared using Scanning Electrochemical Microscopy by Electrochemical reduction of a gold salt at a platinum ultramicroelectrode positioned on top of an unbiased gold surface, modified with a biphenyl dithiol self-assembled monolayer (SAM). The synthesized AuNPs are chemisorbed on the thiolated SAM, and by moving the microelectrode in a lateral direction across the surface while applying a reduction potential, particle-like lines are generated.\nPatterned arrays of gold nanoparticles (AuNPs) are prepared using Scanning Electrochemical Microscopy by Electrochemical reduction of a gold salt at a platinum ultramicroelectrode positioned on top of an unbiased gold surface, modified with a biphenyl dithiol self-assembled monolayer (SAM). The synthesized AuNPs are chemisorbed on the thiolated SAM, and by moving the microelectrode in a lateral direction across the surface while applying a reduction potential, particle-like lines are generated.
Tomoyuki Yasukawa - One of the best experts on this subject based on the ideXlab platform.
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MHS - Investigation of oxygen consumption for micropatterns of contractile myotubes by Scanning Electrochemical Microscopy
2015 International Symposium on Micro-NanoMechatronics and Human Science (MHS), 2015Co-Authors: Yuki Igaki, Fumio Mizutani, Tomoyuki YasukawaAbstract:Scanning Electrochemical Microscopy (SECM) has been applied to determining the oxygen consumption of individual myotubes. Reduction currents of oxygen monitored by Pt microelectrode positioned above the myotube decreased after the continuous contraction of myotubes was induced by the application of electric pulses.
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Investigation of oxygen consumption for micropatterns of contractile myotubes by Scanning Electrochemical Microscopy
2015 International Symposium on Micro-NanoMechatronics and Human Science (MHS), 2015Co-Authors: Yuki Igaki, Fumio Mizutani, Tomoyuki YasukawaAbstract:Scanning Electrochemical Microscopy (SECM) has been applied to determining the oxygen consumption of individual myotubes. Reduction currents of oxygen monitored by Pt microelectrode positioned above the myotube decreased after the continuous contraction of myotubes was induced by the application of electric pulses.
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oxygen permeability of surface modified poly dimethylsiloxane characterized by Scanning Electrochemical Microscopy
Chemistry Letters, 2006Co-Authors: Hitoshi Shiku, Takeshi Saito, Chingchou Wu, Tomoyuki Yasukawa, Masaki Yokoo, Tomokazu Matsue, Hiroshi YamadaAbstract:Scanning Electrochemical Microscopy (SECM) was employed to quantitatively characterize the oxygen permeation behaviors of poly(dimethylsiloxane) (PDMS) and surface-modified PDMS. The mass-transfer ...
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Imaging of Diaphorase Micropatterned at Gold Arrays with Scanning Electrochemical Microscopy
Chemistry Letters, 2000Co-Authors: Tomoyuki Yasukawa, Daniel Mandler, Norihiro Kanaya, Tomokazu MatsueAbstract:Diaphorase was hydrophobically immobilized onto a self-assembled monolayer of alkanethiol at an interdigitated Au microarray. The diaphorase activity at the array substrates was imaged with the Scanning Electrochemical Microscopy (SECM) in the presence of NADH and ferrocenemethanol as a redox mediator. The images demonstrate that diaphorase was immobilized onto the SAM layer to form a line-and-space micropattern which reflected the pattern of the Au microarray.
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Characterization and Imaging of Single Cells with Scanning Electrochemical Microscopy
Electroanalysis, 2000Co-Authors: Tomoyuki Yasukawa, Takatoshi Kaya, Tomokazu MatsueAbstract:This article reviews the applications of Scanning Electrochemical Microscopy (SECM) with ultramicroelectrode (UME) as a probe for characterization and imaging of single living cells. The permeation of cell membranes of several redox species was quantitatively estimated from the SECM measurements of the species in the vicinity region of the cells. The rates for the oxygen generation by photosynthesis and the oxygen consumption by respiration were determined for the detailed analysis of localized oxygen concentration around single cells. The images for photosynthetic and respiration activities were obtained with SECM based on the oxygen reduction current. A dual-microdisk electrode was used for simultaneous imaging based on electroactive species to characterize single cells.
