Molekulaar- ja rakubioloogia
facilitating stronger attachments between the cells and the plate.
However, polyethylenimine expresses some toxicity if excess is left in solution.
Transfection reagent
Poly(ethylenimine) was the second polymeric transfection agent discovered, after poly-l-lysine.
PEI condenses DNA into positively charged particles, which bind to anionic cell surface
residues and are brought into the cell via endocytosis. Once inside the cell protonation of the
amines results in an influx of counter-ions and a lowering of the osmotic potential. Osmotic
swelling results and bursts the vesicle releasing the polymer-DNA complex (polyplex) into the
cytoplasm. If the polyplex unpacks then the DNA is free to diffuse to the nucleus.] PEI is
extremely cytotoxic, by two different mechanisms, the disruption of the cell membrane leading
to necrotic cell death (immediate) and disruption of the mitochondrial membrane after
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