摘要
Polyethylenimines (PEIs) are commonly used as a vehicle to deliver and protect siRNA, but the strong interaction still remains to be modulated for efficient siRNA release and silencing. Herein, a single-monomer derived linear-like PEI- co-PEG (LPEI- co-PEG, P <sub>2</sub> ) was synthesized to substantially enhance the siRNA release, but not affect the efficiency of protection. The linear-like copolymer (P <sub>2</sub> ) was only synthesized from a single-monomer by intensive synchrotron X-ray irradiation within 5 min, randomly producing both PEI and PEG segments. The counterpart vehicle, LPEI (P <sub>1</sub> ), was also synthesized for comparison. We found that the P <sub>1</sub> and P <sub>2</sub> were able to prevent siRNA against enzymatic degradation. Most importantly, efficient siRNA release (52%) was only observed in the siRNA/. P <sub>2</sub> complexes and not in the siRNA/. P <sub>1</sub> complexes (<5%), suggesting that the PEG segment may modulate the interaction between siRNA and P <sub>2</sub> segment. Specifically, P <sub>2</sub> as well as P <sub>1</sub> can emit photoluminescence; cancer cells exhibited a detectable photoluminescence after treatment with P <sub>1</sub> and P <sub>2</sub> , indicative of their excellent transfection efficiency. Subsequently, the siGFP/. P <sub>2</sub> complexes knocked down GFP with excellent efficiency (75%) above the siGFP/. P <sub>1</sub> complexes (19%) and siGFP/Lipofectamine complexes (20%). Importantly, the siRNA with anti-VEGF function being associated with P <sub>2</sub> have been demonstrated an excellent efficiency in the suppression of tumor growth. © 2011 Elsevier Ltd.