Anionic Conjugated Polyelectrolytes for FRET-based Imaging of Cellular Membrane Potential

Area of Science:

• Biophysics
• Cell Biology
• Materials Science

Background:

• Visualizing membrane potential is crucial for understanding cellular function.
• Existing voltage-sensitive probes have limitations in sensitivity and specificity.

Purpose of the Study:

• To develop a novel Förster resonance energy transfer (FRET)-based imaging ensemble for enhanced visualization of membrane potential in living cells.
• To evaluate a conjugated polyelectrolyte (FsPFc10) as a FRET donor for a voltage-sensitive dye acceptor (FluoVolt™).

Main Methods:

• Utilized a conjugated polyelectrolyte (FsPFc10) as a FRET donor and FluoVolt™ as a voltage-sensitive dye acceptor.
• Investigated FRET efficiency at various donor/acceptor ratios using dual-channel confocal imaging.
• Assessed cellular viability and membrane potential changes in HEK 293T/17 cells.

Main Results:

• Observed efficient FRET between FsPFc10 and FluoVolt™, resulting in a three-fold enhancement of FluoVolt™ emission at a 1:1 donor/acceptor ratio.
• FsPFc10 demonstrated effective plasma membrane labeling with minimal cellular internalization for 1.5 hours.
• Cells labeled with the FRET pair showed enhanced fluorescence response during membrane potential depolarization compared to using FluoVolt™ alone, with no adverse effects on cell viability.

Conclusions:

• The FsPFc10-FluoVolt™ FRET ensemble provides a sensitive and effective method for visualizing membrane potential in living cells.
• Conjugated polyelectrolytes represent a promising new class of membrane-labeling fluorophores for voltage-sensing applications.