Arginine-rich hydrophobic polyethylenimine: potent agent with simple components for nucleic acid delivery.

Conjugation of various arginine-rich peptide sequences to vectors based on 10 kDa polyethylenimine (PEI) and its hydrophobic derivative (hexanoate-PEI) was investigated as a strategy for improving pDNA and siRNA transfection activities. Six different arginine-histidine (RH) sequences and two arginine-serine (RS) sequences with a range of R/H ratios were designed and coupled to PEI and hexanoate-PEI. All arginine-rich peptide derivatives of PEI significantly enhanced luciferase gene expression compared to PEI 10 kDa alone. Hexanoate-PEI derivatives exhibited higher transfection activity than underivatized PEI vectors. Improved transfection activity may have resulted at least in part from use of higher vector/DNA ratios made possible by reduced cytotoxicity of vectors, and to use of vectors with higher molecular weights. Vectors that were the most efficient in pDNA delivery and transfection were also the most effective in siRNA delivery and protein expression knock down.