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Updated: Aug 6, 2026
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Imaging Membrane Potential with Two Types of Genetically Encoded Fluorescent Voltage Sensors
Published on: February 4, 2016
Live bacterial specific fluorescence quantification via switchable exogenous electric field induced change in
Jeongeun Lee1, Brian Minsoo Lee2, Beelee Chua2
1Department of Environmental Science and Engineering, Ewha Womans University, Seoul, 03760, Republic of Korea.
Biosensors & Bioelectronics
|July 25, 2026
Summary
This study introduces a novel electric-field fluorescence method to detect and quantify live bacteria, differentiating them from dead cells. This technique offers a reliable alternative to existing methods, avoiding false positives and negatives in bacterial detection.
Area of Science:
- Biosensing
- Bacteriology
- Analytical Chemistry
Background:
- Accurate differentiation and quantification of live bacteria are crucial in various fields, including clinical diagnostics and food safety.
- Existing methods like adenosine triphosphate (ATP) assays can yield false positives, leading to inaccurate results.
- Voltage-sensitive dyes (VSDs) have primarily been used for microscopy, limiting their application in broader quantification assays.
Purpose of the Study:
- To demonstrate the feasibility of using electric-field enabled fluorescence measurement for detecting and quantifying live Escherichia coli K12.
- To develop a bespoke sensor platform for real-time fluorescence measurement of bacterial samples.
- To establish a method that can reliably differentiate between live and dead bacteria, overcoming limitations of current assays.
Main Methods:
- Utilized an exogenous electric field (100 V/cm) to modulate the membrane potential of live bacterial cells in a cuvette.
- Employed the voltage-sensitive dye dipropylthiodicarbocyanine iodide (diS-C3-(5)) to monitor changes in bacterial membrane potential via fluorescence.
- Captured the movement of the VSD in and out of live bacterial cells using a custom fluorescence sensor platform.
Main Results:
- Successfully detected and quantified live bacteria over a concentration range (OD600nm = 0 to 1.0) with a measurement duration of 180s (R² = 0.85).
- Observed significant VSD signals for live bacteria (3.56% to 16.54%) compared to dead bacteria (-0.09% to 0.93%).
- The proposed method accurately differentiated live from dead bacteria, unlike commercial ATP kits that produced false positives.
Conclusions:
- The electric-field enabled fluorescence measurement is a feasible and effective method for detecting and quantifying live bacteria.
- This technique successfully differentiates live from dead bacteria, offering improved accuracy over traditional methods.
- The study repurposes VSDs for broader applications in fluorescence-based bacterial biosensors and quantification assays.
Keywords:
Exogenous electric fieldFluorescence measurementLive bacterial detectionMembrane potentialVoltage-sensitive dye
