2 principle of the multiporator – Eppendorf Multiporator - Electroporation User Manual
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Release of aluminum during electroporation
Commercially available disposable cuvettes usually contain aluminum electrodes. Aluminum is released from the
electrodes under both acidic and alkaline conditions. The shift in the pH value inside the cuvette, which can be observed
after millisecond pulses, leads to a release of large quantities of cytotoxic aluminum ions into the pulse medium. The
Multiporator's Soft Pulses prevent any cell-damaging increase in the aluminum concentration in the cuvette (2).
Hypoosmolar conditions
The hypoosmolar pulse medium contains far fewer osmotically active substances than culture media or physiological
buffer solutions, such as PBS. In a hypoosmolar medium, the cell absorbs water and swells up. Both the cell and its
nucleus assume a rounded form and the cell membrane becomes detached from the cytoskeleton, thereby greatly
facilitating electroporation of the cell.
Na
+
/ K
+
gradient of the cell
Eukaryotic cells build up a gradient in the concentration of sodium and potassium ions across the cell membrane. When
electroporation has caused the membrane to become highly permeable, (particularly for small ions), the Na
+
/K
+
gradient
breaks down locally. The presence of sodium ions in the electroporation buffer (in PBS, for example) makes the situation
even worse, since Na
+
ions enter the cell. With K
+
as its sole cation, the special Multiporator
®
electroporation buffers
prevent sodium from entering the cell and, moreover, stops the K
+
gradient from collapsing completely.
The synergy of the Multiporator
®
and the buffer system
The quality of the Multiporator's performance is derived from the combination of device and pulse medium. The
Multiporator
®
applies Soft Pulses, which lead to a gentle permeation of the cell membrane. The electronically regulated
voltage curve guarantees high reproducibility. In combination with the Multiporator
®
, the special electroporation buffer
fulfills several different functions.
1. Low electrical conductivity prevents high current flow and the resulting changes in pH values and therefore prevents
an increase in the release of cytotoxic aluminum.
2. The low osmolarity of the pulse medium enables the cell to swell up and round off, thus enabling an easier and more
controlled electroporation.
3. The ion composition of the buffer maintains the Na
+
/K
+
gradient of the cells.
The synergy of the device and the pulse medium is a result of these fundamental electroporation factors being taken into
consideration.
2 Principle of the Multiporator®
2 Principle of the Multiporator®
Multipor_Appli_E_poration_en.fm Seite 30 Montag, 30. Januar 2006 2:17 14