Polycationic cyclodextrins (CDs) were complexed with plasmid DNA and their effectiveness as vectors was tested on COS-7 cells. These CDs were modified with pyridylamino, alkylimidazole, methoxyethylamino or primary amine groups at 6-positions of the glucose units. Uncharged CDs, β-CD, hydroxypropyl-β-CD, and dimethyl-β-CD were also tested, but these did not form stable complexes with the DNA and produced only a slight ...