The enhancement of transfection efficiency of cationic liposomes by didodecyldimethylammonium bromide coated gold nanoparticles

The development of transfection enhancement of liposomes with attributes of high stability and easy handling in gene therapy is challenging. In this study, we report didodecyldimethylammonium bromide (DDAB, a cationic lipid) coated gold nanoparticles (DDAB-AuNPs), which can enhance the transfection efficiency generated by two kinds of commercially available cationic liposomes: Lipotap and DOTAP. It showed that DDAB-AuNPs at the optimal concentrations could produce more than 2 times increase when measuring the number of cells expressed green fluorescent protein and 48-fold increase for luciferase levels after transfection, respectively. The electrophoretic mobility shift assay (EMSA) and confocal laser scanning microscopy (CLSM) experiments showed that more DNA molecules binding to the lipoplexes after adding DDAB-AuNPs. In addition, the flow cytometry (FCM) results indicated that DDAB-AuNPs increased cellular uptake efficiency of DNA molecules, which might account for the enhancement of transfection efficiency. It has also been found that the DDAB-AuNPs could decrease the cytotoxicity of liposomes to the cells.