One-step preparation of gold nanovectors using folate modified polyethylenimine and their use in target-specific gene transfection

Gene transfection, as an effective treatment for inherited and acquired life threatening diseases caused by genetic deficiencies and abnormalities, has evolved as a promising therapeutic strategy for cancer and other intractable diseases. Non-target-specific vectors will affect normal cells as well as pathogenic cells, resulting in a relative decrease in transfection efficiency and unnecessary cytotoxicity. In the present work, gold nanoparticles (AuNPs) functionalized with folate (FA)-modified polyethylenimine (PEI-FA) were prepared by a single step method (without additional reducing agent) for targeted gene transfection in tumor cells. Moreover, an improved compound vector system was developed by mixing PEI-AuNPs and PEI-FA-AuNPs. It was shown that the compound vector system not only greatly increased transfection efficiency in HeLa cells, but also reduced cytotoxicity. By comparison, the transfection efficiency in L929 cells lacking folate receptor, was clearly lower than in tumor cells. The specific gene transfection of HeLa cells using this vector system could be clearly observed by confocal laser scanning microscopy in a co-culture system of HeLa cells and L929 cells. This transfection system with high-efficiency, high-specificity and low-toxicity appears to have potential in targeted cancer treatment and drug delivery.