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A Simple Approach to Perform TEER Measurements Using a Self-Made Volt-Amperemeter with Programmable Output Frequency
In This Article
Summary
Here, we demonstrate how to set up an inexpensive volt-amperemeter with programmable output frequency that can be used with commercially available chopstick electrodes for transepithelial/endothelial electrical resistance measurements.
Abstract
Transepithelial/endothelial electrical resistance (TEER) has been used since the 1980s to determine confluency and permeability of in vitro barrier model systems. In most cases, chopstick electrodes are used to determine the electric impedance between the upper and lower compartment of a cell culture filter insert system containing cellular monolayers. The filter membrane allows the cells to adhere, polarize, and interact by building tight junctions. This technique has been described with a variety of different cell lines (e.g., cells of the blood-brain barrier, blood-cerebrospinal fluid barrier, or gastrointestinal and pulmonary tract). TEER measurement devices can be readily obtained from different laboratory equipment suppliers. However, there are more cost-effective and customizable solutions imaginable if an appropriate voltammeter is self-assembled. The overall aim of this publication is to set up a reliable device with programmable output frequency that can be used with commercially available chopstick electrodes for TEER measurement.
Introduction
Epithelial and endothelial cells function as cellular boundaries, separating the apical and basolateral sides of the body. If they are connected through tight junctions, passive substance diffusion through the paracellular spaces is restricted1, resulting in the formation of a selectively permeable barrier. Several artificial barrier systems have been developed2 using microvascular endothelial cells (HBMEC, blood-brain barrier3,4,5,6,7), choroid plexus epithel....
Protocol
1. Assembly of a basic volt-amperemeter for TEER measurement
- Prepare a standard USB charger as the 5 V D.C. power supply, a USB extension cord, a microcontroller that will be used as a programmable square wave generator, two standard multimeters that are able to measure alternating current and voltage as root mean square (True-RMS), four cables with banana plugs, a telephone extension cord with a RJ14 female connector including six pins with the inner four wired (6P4C), two short cables, a luster terminal, a .......
Representative Results
To compare the operation of a self-assembled voltammeter with its commercially available counterpart, a voltage oscillogram of both devices was recorded.
As shown in Figure 2A, the reference instrument generated a square wave signal with an amplitude of 80 mV and an oscillation time of 80 ms, which corresponds to a frequency of 12.5 Hz, when operating on-load with a 1 kΩ test resistor.
.......Discussion
Before a self-made voltammeter can be used in a daily routine, it is essential to check the device for proper function. In our case, a half-time of oscillation of 40 ms (12.5 Hz) was programmed, but the effective oscillation time turned out to be 60 ms (16.7 Hz). This inaccuracy of the microcontroller's time emitter had no detectable impact on TEER measurements. It might be best to determine the actual frequency using the frequency setting of one of the multimeters. If any deviation is found, the source code can be a.......
Acknowledgements
The authors would like to thank Herman Liggesmeyer and Marvin Bende for their expert advice in electrotechnics and informatics.
....Materials
| Name | Company | Catalog Number | Comments |
| 120 kOhm resistor | General (generic) equipment | ||
| Banana plug cables | General (generic) equipment | ||
| Cables | General (generic) equipment | ||
| Chopstick electrode | Merck Millicell | MERSSTX01 | |
| Chopstick electrode (alternative) | WPI World Precision Instruments | STX2 | |
| Crimping tool | General tool | ||
| Digispark / ATtiny85 | AZ-Delivery Vertriebs GmbH | Digispark Rev.3 Kickstarter | |
| DMEM:F12 | Gibco (Thermo Fisher) | 31330038 | |
| Fetal calf serum (FCS)/Fetal Bovine Serum (FBS) | Life Technologies | 10270106 | |
| Filter inserts 3µm translucent | Greiner Bioone | 662631 | |
| HIBCPP | Hiroshi Ishikawa / Horst Schroten | ||
| Insulation stripper | General tool | ||
| Luster terminal | General (generic) equipment | ||
| Oscilloscope | HAMEG | Digital Storage Scope HM 208 | |
| Plotter | PHILIPS | PM 8143 X-Y recorder | |
| Software Arduino | https://www.arduino.cc | Arduino 1.8.9 | |
| Soldering iron | General tool | ||
| Soldering lugs | General (generic) equipment | ||
| Telephone cable with RJ14 (6P4C) connector | General (generic) equipment | ||
| Test resistor | Merck Millicell | MERSSTX04 | |
| True-RMS multimeters | VOLTCRAFT | VC185 | |
| USB charger | General (generic) equipment | ||
| USB extension cord | General (generic) equipment | ||
| Voltohmmeter for TEER measurement | WPI World Precision Instruments | EVOM | |
| Voltohmmeter for TEER measurement (alternative) | Merck Millicell | ERS | |
| Wire end ferrules | General (generic) equipment |
References
- Matter, K., Balda, M. S. Functional analysis of tight junctions. Methods. 30, 228-234 (2003).
- Srinivasan, B., et al. TEER measurement techniques for in vitro barrier model systems. Journal of Laboratory Automation
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