Compositions and methods are provided that are useful for the delivery of therapeutic agents, including nucleic acids. The compositions comprises a non-covalent association complex of: a) a positively-charged backbone and b) at least two members selected from: I) a first negatively-charged backbone having a plurality of attached imaging molecules ü) a second negatively-charged backbone having a plurality of attached targetting agents üi) at least one member selected from RNA, DNA, ribozymes, modified oligonucleotides and cDNA endcoding a selected transgene iv) DNA encoding at lest one persistence factor and v) a third negatively-charged backbone having a plurality of attached biological agents wherein the association complex carries a net positive charge and at least one of the two members from group b) is selected from I) iii) or v).Linvention porte sur des compositions et sur des procédés qui sont utilisés dans ladministration dagents thérapeutiques tels que des acides nucléiques. Ces compositions peuvent être préparées avec des composants utiles dans le ciblage des compositions à administrer, ainsi que dans limagerie des composants.
