title: Acetylation of polyethylenimine enhances gene delivery via weakened polymer/DNA interactions.
abstract: We previously reported that gene delivery efficiency of 25-kDa, branched polyethylenimine (PEI) increased upon acetylation of up to 43% of the primary amines with acetic anhydride. In the present work, we investigated the effects of further increasing the degree of acetylation and elucidated the source of the higher gene delivery efficiency. Despite reduced buffering capacity, gene delivery activity continued to increase (up to 58-fold in HEK293) with acetylation of up to 57% of primary amines but decreased at higher degrees of acetylation. Characterization of polymer-DNA interactions showed that acetylated polymers bind less strongly to DNA. Further, a fluorescence resonance energy transfer assay showed that increasing acetylation causes polyplexes to unpackage inside cells to a higher degree than polyplexes formed with unmodified PEI. Overall, the data suggest that the increased gene delivery activity may be attributable to an appropriate balance between polymer buffering capacity and strength of polymer/DNA interactions.
authors.affiliation: Department of Chemical and Biomolecular Engineering and Department of Bioengineering, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Gabrielson
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Pack
mesh_terms: D000107:Acetylation; D000818:Animals; D002460:Cell Line; D018014:Gene Transfer Techniques; D006801:Humans; D051379:Mice; D010957:Plasmids / Q000737:chemistry*; D011094:Polyethyleneimine / Q000737:chemistry*; D020349:Surface Plasmon Resonance
chemical_list: D011094:Polyethyleneimine