Integrated AFM–SECM in Tapping Mode: Simultaneous Topographical and Electrochemical Imaging of Enzyme Activity

Kueng, Angelika; Kranz, Christine; Lugstein, Alois; Bertagnolli, E.; Mizaikoff, Boris

doi:10.1002/anie.200351111

Cited by 153 publications

(137 citation statements)

References 24 publications

(25 reference statements)

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“…AFM (4,5,16), shear force (3,(17)(18)(19), impedance (14,(20)(21)(22), faradaic current (7,14,23), ion current (6,15,24), and electrochemical (25-27) feedback distance-control systems have been developed, but many of these required additional probe modifications for distance control. Impedance-feedback and constant-current distance control are effective methods to obtain high-resolution topography images because they do not require additional modification of the electrode for distance control.…”

mentioning

confidence: 99%

Topographical and electrochemical nanoscale imaging of living cells using voltage-switching mode scanning electrochemical microscopy

Takahashi

Shevchuk

Novák

et al. 2012

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

202

223

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We describe voltage-switching mode scanning electrochemical microscopy (VSM-SECM), in which a single SECM tip electrode was used to acquire high-quality topographical and electrochemical images of living cells simultaneously. This was achieved by switching the applied voltage so as to change the faradaic current from a hindered diffusion feedback signal (for distance control and topographical imaging) to the electrochemical flux measurement of interest. This imaging method is robust, and a single nanoscale SECM electrode, which is simple to produce, is used for both topography and activity measurements. In order to minimize the delay at voltage switching, we used pyrolytic carbon nanoelectrodes with 6.5-100 nm radii that rapidly reached a steady-state current, typically in less than 20 ms for the largest electrodes and faster for smaller electrodes. In addition, these carbon nanoelectrodes are suitable for convoluted cell topography imaging because the RG value (ratio of overall probe diameter to active electrode diameter) is typically in the range of 1.5-3.0. We first evaluated the resolution of constant-current mode topography imaging using carbon nanoelectrodes. Next, we performed VSM-SECM measurements to visualize membrane proteins on A431 cells and to detect neurotransmitters from a PC12 cells. We also combined VSM-SECM with surface confocal microscopy to allow simultaneous fluorescence and topographical imaging. VSM-SECM opens up new opportunities in nanoscale chemical mapping at interfaces, and should find wide application in the physical and biological sciences.high-resolution imaging | living cell imaging | noninvasive | constant-distance mode S canning electrochemical microscopy (SECM) uses an electrode tip for detecting electroactive chemical species and is an effective tool for the investigation of the localized chemical properties of sample surfaces and interfaces (1). Because SECM has high temporal resolution and can be used under physiological conditions, it is particularly well suited for quantitative measurements of (short-lived) chemicals like neurotransmitters, nitric oxide, reactive oxygen species, and oxygen, which are released/ consumed by living cells. In conventional SECM, the probe is often micrometer scale and the probe vertical position is kept at a constant height, a plane, during probe scanning. If the sample topography is not flat, the electrode-sample separation changes during scanning, complicating the SECM measurement and its analysis.Various methods for SECM electrode miniaturization and control of the electrode-sample separation have been advocated in order to improve the resolution of SECM imaging. The reliable fabrication of nanoelectrodes with a small ratio of electrodeinsulation to active electrode (

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mentioning

confidence: 99%

Topographical and electrochemical nanoscale imaging of living cells using voltage-switching mode scanning electrochemical microscopy

Takahashi

Shevchuk

Novák

et al. 2012

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

202

223

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“…This dual functionality is enabled by special probe geometries that ensure a fixed electrode-to-tip distance or accurate control of the tip-to-sample distance. SECM-AFM has been used to study the local electrochemical activity of various substrates, enzyme activity, [20][21][22] and membrane ion transport. 8,23,24 Furthermore, SECM-AFM probes with nanoelectrodes have been developed to improve the electrochemical resolution; 12,13,15,[25][26][27][28][29][30] however, the application of high-resolution SECM-AFMs with disk-type nanoelectrodes is limited to the characterization of probes using the "lift-up" mode to avoid short circuiting.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous imaging of the topography and electrochemical activity of a 2D carbon nanotube network using a dual functional L-shaped nanoprobe

Lee

Sung

et al. 2015

Analyst

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The application of nanomaterials for biosensors and fuel cells is becoming more common, but it requires an understanding of the relationship between the structure and electrochemical characteristics of the materials at the nanoscale. Herein, we report the development of scanning electrochemical microscopyatomic force microscopy (SECM-AFM) nanoprobes for collecting spatially resolved data regarding the electrochemical activity of nanomaterials such as carbon nanotube (CNT) networks. The fabrication of the nanoprobe begins with the integration of a CNT-bundle wire into a conventional AFM probe followed by the deposition of an insulating layer and cutting of the probe end. In addition, a protrusive insulating tip is integrated at the end of the insulated CNT-bundle wire to maintain a constant distance between the nanoelectrode and the substrate; this yields an L-shaped nanoprobe. The resulting nanoprobes produced well-fitted maps of faradaic current data with less than 300 nm spatial resolution and topographical images of CNT networks owing to the small effective distance (of the order of tens of nanometers) between the electrode and the substrate. Electrochemical imaging using the L-shaped nanoprobe revealed that the electrochemical activity of the CNT network is not homogeneous and provided further understanding of the relationship between the topography and electrochemical characteristics of CNT networks.

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“…the oxygen reduction) for determining the working distance was also reported [20]. An alternative route is the combination of SECM with other scanning probe techniques that can control the probe-sample distance, such as scanning force microscopy (SFM) [24][25][26][27][28][29][30], electrochemical scanning tunnelling microscopy (ECSTM) [31,32], and scanning ion-conductance microscopy (SICM) [33,34]. Other SECM hybrid techniques for distance control rely on the reduced damping of a vertically or laterally vibrated probe in close proximity to the substrate.…”

Section: Introductionmentioning

confidence: 99%

High-throughput scanning electrochemical microscopy brushing of strongly tilted and curved surfaces

Lesch

Momotenko

Cortés‐Salazar

et al. 2013

Electrochimica Acta

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a b s t r a c tThe feasibility of high-throughput scanning electrochemical microscopy (SECM) of strongly tilted (tilt angles ≤4 • ) and curved substrates (diameter of curvature ≥9 cm) is demonstrated by brushing them with a soft linear array of carbon microelectrodes. This probe made of thin polymeric layers operates in contact regime to follow the topography of highly unconventional SECM samples while keeping an almost constant working distance. Strong slope variations of the sample lead to a slight misalignment between the axes of the positioning system and the sliding direction of the microelectrode arrays. The resulting positional offsets can be predicted and corrected to yield a correct representation of the spatial relation on the surface of the sample. Moreover, a custom-made holder system ideally suited for precise control of the soft probe inclination angle and alignment with the substrate plane was also developed to perform high-throughput SECM imaging of a 1.2 cm 2 curved metallic pin within less than 2 h.

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Integrated AFM–SECM in Tapping Mode: Simultaneous Topographical and Electrochemical Imaging of Enzyme Activity

Abstract: Surface topography and the enzyme activity of soft bioactive probes can be investigated simultaneously with a new technique. More about this method, a combination of atomic force and scanning electrochemical microscopy, can be found in the following Communication by C. Kranz et al.

Cited by 153 publications

References 24 publications

Topographical and electrochemical nanoscale imaging of living cells using voltage-switching mode scanning electrochemical microscopy

Topographical and electrochemical nanoscale imaging of living cells using voltage-switching mode scanning electrochemical microscopy

Simultaneous imaging of the topography and electrochemical activity of a 2D carbon nanotube network using a dual functional L-shaped nanoprobe

High-throughput scanning electrochemical microscopy brushing of strongly tilted and curved surfaces

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