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Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors
Published on: February 4, 2016
Second-harmonic generation imaging of membrane potential with retinal analogues
Patrick Theer1, Winfried Denk, Mordechai Sheves
1University of Washington, Department of Physiology & Biophysics, Seattle, Washington, USA.
Biophysical Journal
|December 31, 2010
Summary
Second-harmonic generation (SHG) imaging probes, including retinoids and styryl dyes, were evaluated for voltage sensitivity in cell membranes. Probe properties like nonlinear electric susceptibilities influence signal-to-noise ratio for membrane potential imaging.
Area of Science:
- Nonlinear optics
- Biophysics
- Molecular imaging
Background:
- Second-harmonic generation (SHG) is a voltage-sensitive nonlinear optical signal used for imaging membrane potential.
- Understanding probe behavior is crucial for optimizing this imaging technique.
Purpose of the Study:
- To compare the voltage dependence of SHG signals from four different membrane-incorporated probes.
- To analyze the electrooptic mechanism governing SHG and its relation to probe properties.
Main Methods:
- Compared SHG voltage dependence of all-trans retinal, AR-3, AR-4, and FM4-64 in HEK-293 cells.
- Analyzed data using an electrooptic model based on nonlinear electric susceptibilities (χ² and χ³).
Main Results:
- Determined voltage sensitivity, minimal SHG voltage, and signal amplitude for each probe.
- Found χ² and χ³ to be complex for most probes, indicating proximity to molecular resonances.
- Signal-to-noise ratio depends on probe location and χ³ in the far-from-resonance case.
Conclusions:
- Probe characteristics, specifically nonlinear electric susceptibilities, significantly impact SHG signal quality for membrane potential imaging.
- Optimizing probe selection and placement is key for sensitive voltage imaging.
