Enhanced Delivery of Bioactive Molecules to Intracellular Environments Utilizinga Cytosolically Reducable Grafted Analogof Polyethylenimine

Abstract

The use of cationic polymers for the delivery of DNA to mammalian cells has generated significant interest due to the intrinsic properties associated with these delivery vector systems. One particular system utilizing polyethylenimine (PEI) has been rigorously investigated. A major drawback associated with PEI is the cytotoxicity of the vector/delivery system. In an effort to combat this adverse side effect we have synthesized a novel random block copolymer based upon low molecular weight PEI. Here we report the grafting of Traut's reagent to residual primary amines of PEI to form a random block copolymer. The copolymer introduces a disulfide bridge upon oxidation of Traut's reagent capable of intracellular reduction. We confirm the successful grafting of this agent through FTIR and C-13 NMR. Molecular weight determination of the grafted copolymer was performed through HPLC-SEC and light scattering experiments. This polymer retains the ability to deliver GFP encoding plasmid DNA to 3T3 fibroblasts. Transfection levels were found to be approximately 90%. Transfection of T7 RNA dependent DNA polymerase was also performed utilizing our copolymer. We find successful activation of a virally introduced RNA transcript.