Gene therapy which is completely distinct from conventional therapeutics has emerged as a promising strategy for the treatment of putative and myriad human diseases including cancers.In this study,a tailor-made cationic guanidinylated pullulan derivative(OGG3P)was successfully developed via click reaction between octa-guanidine modified generation 3 L-lysine dendrons and azidated pullulan as a promising vector platform for gene therapy.FT-IR,MS and 1H-NMR were performed to validate the structures of the resulted pullulan derivatives.The gel retardation assay demonstrated the OGG3P could retard DNA at a rather low weight ratio of 0.4.