Voltage-Sensitive Optical Probes for Measuring Cell Membrane Potentials: An Update and Applications to “Nonexcitable” Cells

Nanotechnology and Cancer Bioelectricity: Bridging the Gap Between Biology and Translational Medicine

“…Voltage-sensitive indicators can be classified in two subcategories: voltage-sensitive dyes and genetically encoded voltage indicators. [153] The first act by establishing chemical bonds with molecules expressed by cell membranes to generate a voltage-dependent optical signal, [153] and have been deployed for measuring fluctuations in non-excitable cells as well as to follow voltage dynamics across single neurons or cortical areas. [153,154] Genetically encoded voltage indicators (GEVIs) were further developed to allow targeting of cell type-specific promoters in genetically tractable cells or organisms.…”

“…[153] The first act by establishing chemical bonds with molecules expressed by cell membranes to generate a voltage-dependent optical signal, [153] and have been deployed for measuring fluctuations in non-excitable cells as well as to follow voltage dynamics across single neurons or cortical areas. [153,154] Genetically encoded voltage indicators (GEVIs) were further developed to allow targeting of cell type-specific promoters in genetically tractable cells or organisms. [154,155] Hybrid voltage indicators, which combine a voltage-sensitive dye with a genetically encoded component, have been also developed and are discussed elsewhere.…”

“…[137] Genetically Encoded Voltage Indicators: Genetically encoded voltage indicators (GEVIs) may be a promising alternative in this direction, providing high specificity. [153,157] GEVIs have been extensively employed to record the electrical activity of the brain with enhanced sensitivity and temporal resolution compared to calcium indicators, and this field of research is currently active toward the development of new indicators. [128,154,158,159] The main requirements for a GEVI to record electrical fluctuations in cells are photostability, brightness, speed of operation, sensitivity, and specificity, to achieve one and two-photon voltage imaging.…”

“…Optical technologies have been suggested as a promising technique to address such challenges, and are based on the use of voltage‐sensitive indicators, which comprise voltage‐sensitive dyes and genetically encoded voltage indicators. [ 153 ] Other optical technologies revolve around the combination of 3D electrodes with dyes, and electrochromic electrode materials, both providing an optical readout of cellular electrical signals. [ 7,129 ]…”