The membrane lipid bilayer is almost an insulator with much higher electric resistance compared to the cell plasma. Therefore the electric potential applied on a cell during electroporation is mostly shouldered by the cell membrane and the cell plasma is protected. Macromolecules such as DNA come to a stall after crossing the membrane with the sudden drop of electric field strength. After electroporation, slower cell-autonomous trafficking takes over to distribute the macromolecules to different cellular compartments.
Traditionally the electroporation process is known to be highly toxic to the cells from the destruction of cell membranes. However, it is reassuring that any surviving cells would not experience internal damages since cell survival would require membrane integrity and membrane integrity is an insurance for internal protection.
Biological membrane composition is not a major factor in the physical process of electroporation. Unlike chemical transfection methods and transduction by viral vectors, electroporation can be performed with all types of cells efficiently and conveniently.
2. ELECTRIC CURRENT FIELD
① The cell membrane resembles an insulator and the electric current warps around a cell.
② In a series circuit, voltage distributes in proportion to the resistance and the cell membrane shoulders most of the voltage applied on the cell.
③ Only one terminal surface is effective for electroporation of charged molecules such as DNA.
④ The voltage within the cell plasma is minimal and insufficient for DNA movement once it has crossed into the cell. Slower cellular mechanisms take over after electroporation for translocation of DNA within cell plasma.
⑤ The voltage on the cell nucleus is minimal and it is shouldered by the nucleus envelope. Inside the nucleus there is virtually no electric current and electroporation is not associated genotoxicity.
■ Effective Cells: all types of eukaryotic cells including all cell lines, primary cells, stem cells, blood and immune related cells, neurons, fetus cells and plant cells.
■ Effective Biomolecules: DNA, RNA, siRNA, peptides and proteins
■ Applicable Experiments: transient expression, stable expression, gene knock-in/knock-out, siRNA transfection.
■ Fields of Study: molecular and cellular biology, immunology, hematology, neuroscience, cancer research and drug discovery.