A highly water-soluble perylenediimide-core poly(amido amine) (PDI-PAmAm) with peripheral amine groups has been synthesized. The central PDI chromophore allows optical monitoring of relevant cellular experiments by fluorescence microscopy. The PAmAm shell provides the steric bulk that notably suppresses the aggregation of the central PDI chromophore in aqueous solution. The peripheral amines provide water solubility and positive charges, and also serve as active sites for the further growth of

    PAmAm. PDI-PAmAm can be rapidly internalized into live cells with high efficacy of gene delivery and low cytotoxicity. Both in vitro and in vivo experiments demonstrate the high gene transfection efficacy of PDI-PAmAm.