Multichannel Systems MEA Manual - Manual (Page 35)

MEA Manual
35
5 MEA Handling
Warning: If possible, use only liquids or cleaning solutions with a neutral pH = 7 on MEAs. Do not
expose MEAs with a silicon nitride insulation or TiN electrodes to basic liquids (pH > 7) or aggressive
detergents for a longer period of time. Basic or aggressive liquids may damage TiN electrodes
irreversibly.
Warning: It is absolutely necessary to rinse the MEAs thoroughly with distilled water after treatment
with detergent, particular when using Terg-A-Zym before heat sterilization (dry heat sterilization
is not recommended). Otherwise the potential rests of the detergent may burn into the glass carrier
of the MEA and may destroy the electrodes.
Warning: Do not touch the electrode field in any way during the coating or cleaning procedure.
Keep all instruments, tissues, pipette tips, and similar at a safe distance from the recording area.
The electrodes are easily damaged (except EcoMEA electrodes).
5.1 Hydrophilic Surface Treatment
The surface of new MEAs is hydrophobic, and even hydrophilic MEAs tend to become hydrophobic again
during storage. A hydrophobic surface prevents attachment and growth of the (hydrophilic) cells. The first
step in preparing a MEA for use is therefore to ensure that the surface is hydrophilic enough for coating
and cell adhesion.
To test this without contaminating the surface, place a small drop of water on the MEA surface outside the
culture chamber. If the drop does not wet the surface, you likely need to perform one of the following
steps, in particular when using new arrays.
Literature
Ulrich Egert, Thomas Meyer (2004); Heart on a Chip — Extracellular multielectrode recordings from cardiac
myocytes in vitro, "Methods in Cardiovascular Research", S. Dhein and M. Delmar (eds.)
5.1.1 Plasma Cleaning
Laboratories with access to electron microscopy facilities are likely to have a sputter device or a plasma-
cleaning chamber (for example Plasma Technology, Herrenberg, Germany or PDC-32G from Harrick Plasma,
Ithaca, NY, United States). MEAs can be treated in these chambers with low vacuum plasma for about two
minutes. The MEA surface is exposed to a gas plasma discharge, which will make the surface polar and
thus more hydrophilic. The treatment gives a very clean and sterile surface that can be coated readily with
water-soluble molecules. Note that the effect wears off after a few days.
5.1.2 Protein Coating
If protein coating is acceptable in the planned experiments, there is another quick and simple way to render
the surface hydrophilic.
1. Sterilize the MEAs as described below.
2. Place approximately 1 ml of a concentrated, sterile protein solution (for example, albumin, fetal calf serum
or similar) onto the culture region for about 30 min.
3. Wash the culture chamber thoroughly with sterile water afterwards. The MEA can then be directly used for
cell culture.