Enhancement of the Transfection Efficiency of Poly(ethylenimine) by Guanidylation

Chemists have not only developed new drugs but also some novel methodology for drug or gene delivery. Both the synthesis of new delivery carrier and the development of new formulation of existing materials could be a good target of chemists in these fields. Previously, gene delivery had also belonged to only biological field owing to the viral vector, 1 but it entered into the area of chemistry after the development of synthetic non-viral vectors. 2 Several non-viral vectors composed of polymers, 3 lipids, 4 metals, 5 etc. have various merits over viral vectors including low toxicity, mass production, and the capacity for the gene even though they had relatively lower transfection efficiency than the viral vectors. Some polymeric vectors, such as poly(ethylenimine) (PEI) 6 and poly(amidoamine) (PAMAM) 7 showed the highest transfection efficiencies among non-viral gene delivery vectors, which were comparable to those of the viral vectors. It was suggested that the high transfection efficiency of PEI or PAMAM could be explained by the endosome buffering effect originated from its high charge