Polyethylenimine toxicity

Forrest ML, Koerber JT, Pack DW (2003) A degradable polyethylenimine derivative with low toxicity for highly efficient gene delivery. Bioconjug Chem 14 934-940... 

Polyethylenimine has been shown to be highly effective against ascite tumors53. The high toxicity of the polymer is completely eliminated, without significant reduction of its activity, by grafting with monomeric serine and/or histidine residues54. ... 

Polyethylenimine (PEI) grafted onto sidewalls of MWCNTs (Category I.C) was used as a plasmid delivery vehicle. The PEI-MWCNTs were efficient in delivery of a plasmid containing the luceiferase gene. The observed toxicity was lower than that of PEI when used alone. 

The pendent allyl group was further oxidised to an epoxy group, which was then grafted to low MW polyethylenimine to construct novel, nonviral gene delivery carriers with low toxicity and high gene-transfection efficacy [54, 55]. 

Optimization of cationic polymers is based on the following motivation to improve the gene transfer efficiency, to make carriers less toxic and more biocompatible. Strategies include the optimization and modification of commonly used polymers such as polylysine or polyethylenimine (see below, this section) and the generation of novel, biodegradable polymers (see Sect. 3.3). 

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