Enhanced transfection of polyplexes based on pluronic-polypropylenimine dendrimer for gene transfer

Third generation cationic dendritic polymeric polypropyleneimine (PPI) was modified by Pluronic P123 and investigated for gene delivery. The cytotoxicity of P123-PPI was evaluated by the MTT assay and shown to be much lower than that of PPI alone. P123-PPI and PPI can both condense plasmid DNA into nanoparticles with a size of approximately 100 nm and a zeta potential of about 15 mV at the N/P ratio 20:1. The nanoparticles can protect plasmid DNA from being digested by DNase I at a concentration of 0.4 U/μg DNA. The nanoparticles were resistant to dissociation induced by 50% fetal bovine serum and 75 μg/mL sodium heparin. The transfection efficiency of SPC-A1 cells using P123-PPI/DNA nanoparticles was much higher than the transfection utilizing PPI/DNA nanoparticles. The addition of free P123 during the preparation of P123-PPI/DNA nanoparticles could significantly enhance the transfection efficiency in the presence of 10% fetal bovine serum. Therefore, P123-PPI/DNA complex nanoparticles may be a safe, efficient and promising cationic conjugate for gene delivery.