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Making, Testing, and Using Potassium Ion Selective Microelectrodes in Tissue Slices of Adult Brain

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Vesicle-Based Sensors for Extracellular Potassium Detection.

Margrethe A Boyd¹, Anna M Davis¹, Nora R Chambers¹

¹Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA.

Cellular and Molecular Bioengineering

|November 15, 2021

Summary

We developed a novel vesicle-based sensor for detecting potassium (K+) ions with enhanced specificity. This new platform utilizes membrane channels to improve ion detection in challenging biological environments.

Keywords:

Biosensing Fluorescence Ionophore Liposome Membrane

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Last Updated: Oct 13, 2025

Making, Testing, and Using Potassium Ion Selective Microelectrodes in Tissue Slices of Adult Brain

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Published on: May 7, 2018

Double-barreled and Concentric Microelectrodes for Measurement of Extracellular Ion Signals in Brain Tissue

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Published on: September 5, 2015

Use of Label-free Optical Biosensors to Detect Modulation of Potassium Channels by G-protein Coupled Receptors

Use of Label-free Optical Biosensors to Detect Modulation of Potassium Channels by G-protein Coupled Receptors

Published on: February 10, 2014

Area of Science:

Biomedical Engineering
Chemical Biology
Sensor Technology

Background:

Detecting biological ions in situ is challenging due to nonspecific fluorescent indicators.
Existing sensors struggle with distinguishing ions of similar charge states, like potassium (K+) and sodium (Na+).
A new approach is needed to create specific and reliable ion detection methods.

Purpose of the Study:

To develop a vesicle-based sensor for specific in situ detection of potassium (K+) ions.
To overcome the limitations of nonspecific fluorescent indicators in biological samples.
To create a versatile platform for detecting various biological analytes.

Main Methods:

Phospholipid vesicles were assembled with valinomycin (a K+-specific transporter) and encapsulated benzofuran isophthalate (PBFI, a K+-sensitive dye).
The specificity, kinetics, and reversibility of the encapsulated dye were analyzed using plate readers and fluorimeters.
The vesicle sensors were tested in bacterial cultures (E. coli) to assess K+ levels in relation to cell density.

Main Results:

Vesicle sensors demonstrated significantly improved specificity for K+ detection over free dye, even in the presence of sodium (Na+) and calcium (Ca2+).
The sensor successfully reported both increases and decreases in extracellular K+ concentration.
The vesicle sensors were capable of detecting changes in K+ levels within bacterial cultures.

Conclusions:

A novel platform for extracellular ion detection was developed, leveraging ion-specific membrane transporters for enhanced specificity.
This approach offers a broadly applicable method for designing biological sensors for hard-to-monitor analytes.
Future applications include adapting the platform for detecting a wide range of biological targets.