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Updated: Apr 26, 2026
Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors
Published on: February 4, 2016
A new phosphorus-rhodamine voltage-sensing dye for optical membrane potential imaging
Meike Höhl1,2, S Suheda Yasarbas3, María Victoria Cappellari4
1Department of Preclinical Imaging and Radiopharmacy, Cluster of Excellence iFIT (EXC 2180) 'Image-guided and Functionally Instructed Tumor Therapies', Werner Siemens Imaging Center, University of Tuebingen, Roentgenweg 13, 72076, Tuebingen, Germany.
We developed a novel phosphorus-rhodamine voltage-sensing dye (VSD 1) for optical imaging. This red-shifted dye offers high sensitivity and microsecond response times, enabling precise measurement of membrane potential dynamics in excitable cells.
Area of Science:
- Biophysics
- Cellular Neuroscience
- Optical Imaging
Background:
- Accurate measurement of membrane potential dynamics is crucial for understanding cellular excitability and signaling.
- Electrophysiological methods offer high temporal resolution but are invasive and have low throughput.
- Existing voltage-sensing dyes (VSDs) face challenges in achieving near-infrared (NIR) emission, high sensitivity, and rapid response.
Purpose of the Study:
- To design, synthesize, and characterize a novel phosphorus-rhodamine-based VSD (VSD 1).
- To achieve a red-shifted spectral profile for enhanced optical imaging capabilities.
- To evaluate the voltage sensitivity and response kinetics of VSD 1 for tracking membrane potential dynamics.
Main Methods:
- Design and synthesis of a novel phosphorus-rhodamine VSD with a phenyl substituent.
- Spectroscopic characterization to determine absorption and emission maxima.
- Voltage-clamp fluorometry in Xenopus laevis oocytes to assess voltage sensitivity and response time.
Main Results:
- VSD 1 exhibits absorption and emission maxima at 715 and 744 nm, respectively, representing the most red-shifted profile among rhodamine VSDs.
- The dye demonstrates robust voltage sensitivity with a linear fluorescence-voltage relationship (ΔF/F of 4.7±1.4% per 100 mV).
- VSD 1 responds to membrane potential changes on the microsecond timescale, enabling faithful tracking of action potentials.
Conclusions:
- VSD 1 is a novel, highly red-shifted voltage-sensing dye with excellent sensitivity and rapid response kinetics.
- The dye's properties make it suitable for high-speed, minimally invasive imaging of membrane potential in excitable cells.
- VSD 1 represents a promising next-generation optical probe for studying cellular excitability and signaling in complex biological systems.
