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By Michael addition polymerization of N,N'-cystaminebisacrylamide (CBA) with variable ratios of 4-amino-1-butanol (ABOL) and ethylene diamine (EDA) or triethylenetetramine (TETA), poly(amido amine) copolymers could be obtained with tunable charge densities. The copolymers were optimized to serve as nonviral vectors in RNA interference (RNAi) to form stable, nanosized polyplexes with siRNA with maximum transfection efficacy. It was observed that at least 20-30% EDA or TETA amino units in the copolymers is necessary to encapsulate siRNA into small and stable polyplexes (< 200 nm). Incorporation of higher amounts of EDA or TETA in the copolymers did not further improve polyplex formation and stability, but the increased cationic charge in these copolymers resulted in increased cytotoxicity and hemolytic activity. Copolymers with 20% EDA showed excellent gene silencing properties in vitro (70% luciferase knockdown in H1299 cells) with negligible cytotoxicity.

Original publication




Journal article


J Control Release

Publication Date





177 - 186


Acrylamides, Amino Alcohols, Biological Availability, Buffers, Cell Line, Tumor, Cell Survival, Dithiothreitol, Electrophoresis, Agar Gel, Ethylenediamines, Gene Expression, Gene Transfer Techniques, Glutathione, Green Fluorescent Proteins, Hemolysis, Humans, Luciferases, Firefly, Magnetic Resonance Spectroscopy, Molecular Weight, Nucleic Acid Conformation, Nylons, Particle Size, Plasmids, Polyamines, RNA Interference, RNA, Small Interfering, Static Electricity, Transfection, Trientine