Polyethylenimine (PEI)

Polyethylenimine (PEI) is a synthetic cationic polymer characterized by a high density of amino groups, existing in both linear and branched molecular architectures. In the field of biotechnology and pharmacology, it is primarily utilized as a potent non-viral vector for the delivery of genetic material, such as DNA and various forms of RNA, into target cells. PEI functions by condensing nucleic acids into nanosized polyplexes through electrostatic interactions, protecting them from degradation and facilitating their cellular entry. Its hallmark mechanism of action is the 'proton sponge' effect, which allows the polymer to buffer endosomal acidification, leading to osmotic rupture and the efficient release of its cargo into the cytosol. While it remains a gold standard for transfection in research, its clinical application is hindered by significant cytotoxicity, especially in high-molecular-weight branched forms, and its lack of natural biodegradability.

Other names

Poly(ethyleneimine)Aziridine polymerPolyaziridinePolyminLinear polyethylenimineBranched polyethylenimine

Polyethylenimine functions via the 'proton sponge' effect, where its high buffering capacity leads to an influx of protons and water into endosomes, causing osmotic swelling and endosomal rupture to release therapeutic cargo into the cytoplasm. It also forms stable polyplexes through electrostatic interactions between its positive amine groups and the negative phosphate backbone of nucleic acids.