To develop novel gene delivery carriers, aminated polysorbate 80 (P80-NH2) was synthesized with strong positively charged properties through the introduction of three amine groups. The resulting P80-NH2 and DNA polyplex exhibited superb condensation abilities due to the high densities of positively charged amines groups. Size and surface charge of polyplex were shown to be well suited for cellular internalization. In addition, the P80-NH2/DNA polyplex demonstrated acceptable transfection efficiency in HeLa cells and was nontoxic relative to the conventional 25-kDa polyethyleneimine system. (C) 2010 American Institute of Chemical Engineers Biotechnol. Prog., 26: 1528-1533, 2010