Single-cell scanning photoelectrochemical microscopy using micro-optical-ring electrodes

Cytochromecoxidase deficiency detection in human fibroblasts using scanning electrochemical microscopy

“…Approaches have been described for the study of living cells using SECM, including the use of depth scans ( 47 , 60 – 63 ) and constant-height lateral scans performed in the x, y -direction ( 39 , 45 , 64 – 66 ) Lateral scans significantly reduce the risk of making physical contact between the electrode and the biological cell. Depending on the imaging system of an SECM instrument, stopping an approach above a cell, especially when using a colored redox mediator, such as TMPD, can be very challenging.…”

“…Biological applications of SECM have been described, including studies of cancer ( 32 – 35 ), cardiac disorders ( 36 , 37 ), oxidative stress ( 38 , 39 ), bacterial metabolism ( 40 – 42 ), and cell interactions in biofilms ( 43 , 44 ). The ability of SECM to detect metabolites locally makes it an ideal tool to discover biomarkers and metabolic redox indicators at the single-cell level ( 39 , 45 , 46 ), which has the potential to enhance the understanding of cellular mechanisms involved in the onset and progression of diseases. The use of SECM for the study of biological cells and tissues has achieved impressive advances in the last two decades.…”

“…For instance, Hu and colleagues have recently utilized platinized carbon nanoprobes to dynamically quantify reactive oxygen and nitrogen species inside single phagolysosomes in living macrophages to better understand the cellular phagocytosis process ( 38 ). In a promising proof-of-concept study, Thomas and coworkers were able to measure the production of oxygen by living algae cells, in situ and in real time, using scanning photoelectrochemical microscopy and micro-optical-ring gold electrodes as powerful detection probes ( 45 ). On the other hand, the regeneration of muscle tissue was recently investigated by Bironaite and colleagues using SECM, and their findings revealed that this electroanalytical method can be used to locally stimulate specific subpopulations of skeletal muscle–derived mesenchymal stem/stromal cells to improve their regeneration potential and functioning, while measuring their redox activity ( 47 ).…”

Recent Developments in Single-Entity Electrochemistry

“…However, the scanning probe tip approaches the sample from the top and leads to geometric limitations for optical microscopy. While optical fibers or long working distance objectives can be incorporated to allow SPM and optical microscopy to be performed on the same side of the sample, − the use of high numerical aperture objectives, which are preferred for most single molecule studies, requires access to both the top and bottom of the sample. In this case, the working electrodes used for coupled SPM-optical experiments must be optically transparent to allow the visualization of the dynamic processes of single NPs.…”

Spatially Resolved Optical Spectroscopic Measurements with Simultaneous Photoelectrochemical Mapping Using Scanning Electrochemical Probe Microscopy

“…However, this may also be used to determine the locations of nonuniform regions. Further improvements to the SR-OS/SPECM method could be realized by using micro-optical ring electrodes. − These types of electrodes may allow for the simultaneous in situ monitoring of the local production/consumption of redox species at illuminated sites, or they could be further modified as sensors to detect local pH changes …”