Grafting zwitterionic polymer chains onto PEI as a convenient strategy to enhance gene delivery performance

Herein, we demonstrated a one-step method for preparing a new gene delivery vector by grafting poly-(2-methacryloyloxyethyl phosphorylcholine) (PMPC) onto the 25 kDa polyethylenimine (PEI 25k) via a TBHP-initiated polymerization. The graft ratio of PMPC on the PEI polymer can be readily controlled, and in this study three PEI-PMPC polymers (PEI-PMPC6%, PEI-PMPC11% and PEI-DMAAPS(24%)) have been prepared with their graft ratios of 6 wt%, 11 wt% and 24 wt%, respectively. The PEI-PMPC polymers exhibit lower protein adsorption and cytotoxicity compared to PEI 25k. Moreover, the PEI-PMPC polymers display satisfactory DNA condensation capability. In the absence and presence of serum, PEI-PMPC6%/pEGFP and PEI-PMPC11%/pEGFP complexes work well and exhibit satisfactory gene transfection efficiencies, which are in general higher than that of PEI 25k/pEGFP, especially in the presence of 10% serum. With these improved gene delivery properties, the PEI-PMPC polymers hold great potential for being used as efficient gene delivery vectors. This strategy may provide a facile and effective way for constructing some other biocompatible materials.