Polyethylenimine
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Linear polyethyleneimines (PEIs) contain all secondary amines, in contrast to branched PEIs which contain primary, secondary and tertiary amino groups. The linear PEIs are solids at room temperature where branched PEIs are liquids at all molecular weights. Linear polyethyleneimines are soluble in hot water, at low pH, in methanol, ethanol, or chloroform. It is insoluble in cold water, benzene, ethyl ether, and acetone. One end of the polymer chain is a methyl group, the other end is a hydroxyl group. It has a melting point of 73-75°C. It can be stored at room temperature.
Polyethyleneimines as an attachment promotor
Polyethyleneimines are used in the cell culture of weakly anchoring cells to increase attachment. PEI is a cationic polymer, the negatively charged outer surfaces of cells are attracted to dishes coated in PEI, facilitating stronger attachments between the cells and the plate.However, polyethylenimine has very strong toxicity.[1]
Polyethyleneimines as a transfection reagent
Poly(ethylenimine) was the second polymeric transfection agent discovered[2], 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 then free to disfuse to the nucleus.[3] [4]. PEI is extremely cytotoxic[5] by two different mechanisms[6], the disruption of the cell membrane leading to necrotic cell death (immediate) and disruption of the mitochondrial membrane after internalisation leading to apoptosis (delayed).
Linear PEI was synthesised by the hydrolysis of poly(2-ethyl-2-oxazoline)[7] and sold as jetPEI[8]. The current generation in-vivo-jetPEI uses bespoke poly(2-ethyl-2-oxazoline) polymers as precursors[9].
References
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- ↑ Boussif, O. et al. A Versatile Vector for Gene and Oligonucleotide Transfer into Cells in Culture and in vivo: Polyethylenimine. Proceedings of the National Academy of Sciences 92, 7297-7301, doi:10.1073/pnas.92.16.7297 (1995)
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- ↑ Hunter, A. C. Molecular hurdles in polyfectin design and mechanistic background to polycation induced cytotoxicity. Advanced Drug Delivery Reviews 58, 1523-1531 (2006)
- ↑ Moghimi, S. M. et al. A two-stage poly(ethylenimine)-mediated cytotoxicity: implications for gene transfer/therapy. Molecular Therapy 11, 990-995 (2005)
- ↑ Brissault, B. et al. Synthesis of Linear Polyethylenimine Derivatives for DNA Transfection. Bioconjugate Chemistry 14, 581-587 (2003)
- ↑ http://www.polyplus-transfection.com/transfection-reagents/high-throughput-screening-jetpei/
- ↑ http://www.wipo.int/pctdb/en/wo.jsp?WO=2009016507&IA=IB2008002339&DISPLAY=DOCS
