Why HEKA? – Listening in on Customer Labs

While looking into selecting the perfect tool for your research you come across a lot of information. A lot of technical data to compare, people to talk to and benefits to evaluate. 

At HEKA we have amazing engineers, capable software developers and a support team that has extensive experience in the lab. Still, would it not be nice to be able to see what your colleagues in the field have to say about our solutions and their experiences? 

We are happy that Dr. Monika Bozem gave us the opportunity to provide you with just that. Between 2012 and 2020 in her role as Senior Scientist Dr. Bozem was Group Leader of the Electrochemical Section in the Biophysics Department of Saarland University. Read here how she and her team have used Scanning Electrochemical Microscopy in a life science application. 

Full Testimonial

Screening of CO2 electroreduction catalysts

The electroreduction of carbon dioxide is an important reaction in view of fuels for both fuel cells and redox flow batteries as well as towards a carbon neutral energy cycle. Hence the reaction has been intensively studied and a range of different catalyst materials have been presented.

In today’s paper “Scanning electrochemical microscopy screening of CO2 electroreduction activities and product selectivities of catalyst arrays” by Francis D. Mayer et al. Sn/SnOx catalysts are investigated using SECM. The final goal of this approach is to obtain a high-throughput screening procedure with the ability of spatial resolution to evaluate local activity changes in the catalysts.

Here, the authors show the capability of SECM for CO2 electroreduction catalyst screenings by comparing three different Sn/SnOx materials towards the production of H2, COad and HCOOand their selectivity. In contrast to traditional SECM experiments where the microelectrode is biased at a constant potenial while moving across the surface, the products are detected in a CV cycle as shown below. This allows for a simultaneous detection of all three relevant reaction products in one experiment.

Presentation of A CV at a Pt microelectrode for the simultaneous detection of H2, COad and HCOO-.
Fig. 1: Cyclic voltammograms indicating the different redox processes during CO2 electroreduction. Image taken from Mayer, F.D., et al. Commun Chem 3, 155 (2020). https://doi.org/10.1038/s42004-020-00399-6.

The screening of the Sn/SnOx catalyst array was performed by conducting and analysing a fast CV (1 V/s) at the Pt microelectrode at each measuring point of the 8750 x 1250 µm map. The Potmaster software of the ElProScan allows to perform matrix scans where advanced protocols can be executed and analyzed which made these experiments possible.

SECM maps created from the analysis of fast CV scans at each point of the map.
Fig. 2: Resulting maps of the catalyst array for each product as analyzed in the CV scans. Image taken from Mayer, F.D., et al. Commun Chem 3, 155 (2020). https://doi.org/10.1038/s42004-020-00399-6.

The analysis showed indeed differences in the product selectivities and shows the great potential of using the combined SECM-CV approach for larger catalyst arrays.

Read the full paper here: Mayer, F.D., Hosseini-Benhangi, P., Sánchez-Sánchez, C.M. et al. Scanning electrochemical microscopy screening of CO2 electroreduction activities and product selectivities of catalyst arrays. Commun Chem 3, 155 (2020). https://doi.org/10.1038/s42004-020-00399-6

Contact us if this application caught your attention and you want to learn more.

Combining SECCM with Microspectroscopy for Evaluation of ROS Generation at non-Pt Fuel Cell Catalysts

Scanning electrochemical cell microscopy (SECCM) is the only technique which allows the study of a material using well-established bulk electrochemical techniques with a resolution of a few micrometer down to the nanometer regime. The measurement takes place in a nano- or microdroplet formed at the end of a nano- or micropipette in contact with the surface of interest. This allows e.g. study of single nanoparticle agglomerates or generally spatially resolved analysis of the sample. The analysis of the data is equivalent to the bulk experiment and often straightforward.

In this paper “Mapping Localized Peroxyl Radical Generation on a PEM Fuel Cell Catalyst Using Integrated Scanning Electrochemical Cell Microspectroscopy” by J. Edgecomb et al. SECCM using a HEKA ElProScan platform was combined with adsorption and fluorescence microscopy allowing the recording of spectra within a 10 µm wetted sample area. A fluorescent dye 6CFL was used to detect the generation of peroxyl radicals during the ORR at the non-Pt catalyst TaTiOx on a Nafion membrane which were indeed formed.

The measurements using this integrated SECCM setup were validated by RRDE bulk measurements and can further be applied to novel fuel cell catalysts.

Edgecomb J, Xie X, Shao Y, El-Khoury PZ, Johnson GE and Prabhakaran V (2020) Mapping Localized Peroxyl Radical Generation on a PEM Fuel Cell Catalyst Using Integrated Scanning Electrochemical Cell Microspectroscopy.
Front. Chem. 8:572563. doi: 10.3389/fchem.2020.572563

Scheme of the SECCM setup with integrated spectrometer for adsorption and fluorescence microspectroscopy in the droplet (left), fluorescence spectra within the droplet of a Nafion membrane with a layer of fluorescence dye 6CFL and active catalyst (middle) and fluorescence intensity during ORR at the active catalyst (right). Reproduced from J. Edgecomb et al. (2020) Front. Chem. 8:572563. Copyright by © 2020 Edgecomb, Xie, Shao, El-Khoury, Johnson and Prabhakaran.

Remote SECM Mini Workshop

We had a great remote mini workshop with Martin Edwards from the University of Arkansas and Hang Ren from Miami University in Ohio and their students from scanning probe microscopy and electroanalytical techniques courses.
Our application scientist Mareike Haensch performed SECM experiments on the ElProScan starting from mounting the sample and microelectrode to recording images in different SECM modes. The students actively participated and suggested changes of parameters to see how it influences the experiment. We hope that this remote “hands-on” experience helps deepen their understanding of SECM in times during which lab courses are not possible in many places around the world.

SECM Tutorial at the ISE Online Meeting

This year Prof. Gunther Wittstock from Oldenburg and Prof. Wolfgang Schuhmann from Bochum, two true experts in the field of scanning electrochemistry microscopy (SECM) will hold an online tutorial at the ISE annual meeting with the title

“Solving research problems by means of scanning electrochemical microscopy (SECM) and related techniques”

The online meeting will consist of online lectures, poster sessions and tutorials.

ISE logo

31st August – 4th September

(The exact time of the tutorial is not yet fixed)

Deadline for registration is 31st of July.

The registration for ISE members is FREE and for non-members it cost 50€ above 30 years and 15€ below 30 years.

Register to take this opportunity and learn everything about SECM that you always wanted to know!

Micropatterning of a photocatalyst surface followed by evaluation of its local catalytic activity

The ElProScan ELP 3 SPECM has been used for an innovative two-step scanning photoelectrochemical microscopy (SPECM) experiment consisting of micropattering and consecutive evaluation of catalytic activty.

In the first step, a BiVO4 seminconductor surface was modified by photodeposition with the electrocatalyst FeOOH to fabricate a photocatalyst system for the photoelectrochemical water splitting reaction. The inverted microscope of the ELP 3 was hereby used to illuminate different spots of the surface with varying illumination time (10, 15, 20 and 25 min) in a matrix scan. This way, a regular pattern with catalytically active spots with different loadings of FeOOH were produced.

In the second step, the photocatalyst pattern was scanned via SPECM and the photocurrent at the sample was recorded yielding a map showing that the highest catalytic activity is found for the spot after 20 min of photodeposition. Additionally, to determine the Faradayic efficiency the oxygen which was produced in the water splitting reaction was detected by the oxygen reduction reaction (ORR) at a microelectrode . The microelectrode was aligned with inverse microscope and therefore with the illuminated sample area. Shear Force Sensing was used to keep a constant distance between microelectrode and sample surface to probe the pure catalytic activity without effects of sample topography. The z position of the microelectrode is further used to obtain the topography map of the sample.

Photodeposition of FeOOH catalyst spots with different loading on a BiVO4 semiconductor surface by SPECM (left) and consecutive evaluation of their catalytic activity by SPECM (right). The recorded signals are the photocurrent at the sample, the locally produced oxygen at the microelectrode and the topography via Shear Force Sensing.

Chen, S., Prins, S. and Chen, A. (2020) ‘Patterning of BiVO4 Surfaces and Monitoring of Localized Catalytic Activity using Scanning Photoelectrochemical Microscopy’, ACS Applied Materials & Interfaces.

These experiments show that the multi-functional ELP 3 SPECM can be used to easily fabricate catalyst libraries which can in a second step be evaluated regarding their local catalytic activity greatly accelerating the search for new highly active catalyst materials.

The latest model of our ELP 3 SPECM-FL has a second illumination port for small spot illumination for illuminated spot sizes down to 5 µm. This match of illuminated sample area and microelectrode size further improves the collection efficiency at the microelectrode and the quality of the experimental results.

Influence of mechanical microenvironment on the redox state of cardiomyocytes

The regulation of intracellular redox microenvironment is of immense importance for the homeostasis of cells. The mechanical microenvironment plays a key role in the regulation of the phenotype and function of cardiac cells, which are strongly associated with the intracellular redox mechanism of cardiomyocytes. Glutathione (GSH) is the most abundant intracellular nonprotein thiol and functions as one of the most important endogenous antioxidants in cells. Under normal physiological conditions, intracellular chemical microenvironment is maintained in a relatively reduced state due to a higher GSH concentration than that of glutathione disulfide (GSSG). the relationship between the redox state of cardiomyocytes and their mechanical microenvironment remains elusive.

The Li Lab at the BEBC at Xi’an Jiaotong University investigated the influence of the mechanical microenvironment on the redox state of single cardiomyocytes in situ by SECM. The redox state was studied by quantifying the GSH level of living cardiomyocytes at single-cell level. Different mechanical microenvironments were simulated using polyacrylamide (PA) gels of different stiffness as the substrate. SECM depth scans were recorded and aprroach curves extracted to obtain rate constants kf for the reaction of the redox mediator FcCOOH and GSH which are a direct measure of GSH levels.

Li, Y., Lang, J., Ye, Z., Wang, M., Yang, Y., Guo, X., Zhuang, J., Zhang, J., Xu, F. and Li, F. (2020) ‘Effect of Substrate Stiffness on Redox State of Single Cardiomyocyte: A Scanning Electrochemical Microscopy Study’, Analytical Chemistry.

It was shown that stiffer substrates induce a more oxidative state of the cardiomyocytes compared to the softer substrates. This result can contribute to understand the effect of mechanical factors on the cell’s redox mechanism, such as the myocardial fibrosis caused overaccumulation of ECM.

SECM proved to be a sensitive, label-free and in situ technique for the investigation of redox state in single-cells.

HEKA’s ElProScan ELP 3 provides the ideal conditions for working with live single cells. The inverted microscope allows visual control of the cells and exact positioning of the microelectrode and a range of heated stages for working under physiological conditions. The unique depth scan allows the study of concentration profiles above single cells.

Covid-19 Update

We are committed to supporting your research during this challenging time by providing tools to help you find better treatments and improve the quality of lives.  As a global company, we operate in countries which have been impacted to varying degrees, and as such have taken the appropriate precautionary measures to ensure our employees’ health and safety is protected, while providing no disruption in your service:

  • Product manufacturing and order fulfillment: We have taken additional steps to ensure the safety of our employees, yet still maintain our normal order fulfillment times.
  • Sales support / consultation: To better support you during this period, we encourage you to schedule a virtual meeting with your local sales consultant. We find it to be the next best thing to visiting your site as it allows us to share relevant content for your use case / study design. 
  • Technical support and customer service: Our support teams remain available during our standard business hours to answer questions you may have.

We will continue to monitor the potential impact of the novel coronavirus (COVID-19). For any questions, please contact your local sales representative.

Your HEKA Team

FSCV Update

Did you know that you can perform Fast-Scan Cyclic Voltammetry (FSCV) experiments with your ECP 10 USB Patch Clamp Amplifier or your Potentiostat of the PG Family?

FSCV with potential program in red and resulting current response in blue.

FSCV is used for detecting neurotransmitters, hormones or metabolites in live biological systems. A carbon fiber microelectrode is brought into close proximity to the site under investigation and a potential program is applied. It consists of a rapid triangular potential ramp of 400 V/s to detect the analyte by oxidation or reduction and a wait time at a holding potential between ramps to pre-concentrate the analyte at the microelectrode. The temporal resolution of FSCV is in the range of 100 ms and it has a high selectivity and sensitivity (10 nm LOD dopamine).

FSCV can be combined with other techniques such as fluorescence imaging or patch clamp.

PATCHMASTER and POTMASTER have new features for FSCV with

  • automatic peak detection,
  • automatic background subtraction,
  • synchronized triggers for external stimulus generators.

The potential program can be freely designed in the Pulse Generator File.

Learn more on our FSCV method page.

Contact us if you want to perform FSCV experiments and we will provide you with a FSCV configuration for PATCHMASTER or POTMASTER.