Gene therapy is a promising approach to treating diseases that caused by genetic defects or mutation.Non-invasive imaging of gene is a powerful tool in understanding the biodistribution and pharmacokinetics of vectors after in vivo administration.In the current research

amphiphilic copolymers

which were utilized to deliver a magnetic resonance imaging (MRI) contrast agent and pDNA simultaneously

were obtained by modifying hyperbranched polyethylenimine with biodegradable hydrophobic segment (PCL).Synthesis of the copolymer was presented in details and chemical characterization of these copolymers was carried out using 1H-NMR spectroscopy and FT-IR spectrum.The polyethylenimine-g-poly(ε-caprolactone)(PEI-g-PCL) could self-assemble into nanoparticles were between 130 to 160 nm in diameter and displayed zetapotentials between +30～40 mV.The morphology investigated by SEM showed PEI-g-PCL aggregates were micellar structure.The MRI contrast agents-carrying capacity of these polymeric micelles was evaluated by using hydrophobic superparamagnetic iron oxide nanoparticles (SPIO) as the model contrast agents.In addition

this kind of polymeric micelles have been evaluated in vitro as nonviral gene delivery systems. SPIO could be loaded into the hydrophobic core of PEI-g-CL micelle by emulsion/solvent evaporation technique.The PEI-g-PCL micelles were capable of complexing plasmid DNA into nanoparticles with diameters about 200 nm

and these complexes transfect 293 cells with high efficiency.These results suggest that PEI-g-PCL has the potential combined application in gene delivery and MRI diagnosis.