Polyethyleneimine-Coated Gold Nanoparticles: Straightforward Preparation of Efficient DNA Delivery Nanocarriers.

A novel one-pot methodology for the synthesis of PEI-coated gold nanoparticles (AuPEI-NPs) that combines the reductant-stabilizer properties of PEI and microwave irradiation starting from hydrogen tetrachloroaurate (HAuCl4) and branched PEI 25kDa (b25kPEI) is reported. The method is straightforward, green and low-cost where the Au:PEI w:w ratio (1:1 to 1:128) is a key parameter to modulate their capabilities as DNA delivery nanocarriers. Transfection assays in CHO-k1 cells demonstrate that AuPEI-NPs with 1:16 and 1:32 w:w ratios behave as effective DNA gene vectors with improved transfection efficiencies (2-fold) and significant lower toxicity compared with unmodified b25kPEI and Lipofectamine 2000. The transfection mediated by these AuPEI-NPs-DNA polyplexes use preferentially the caveolae-mediated route for intracellular internalization as showed by studies carried out using specific internalization inhibitors as well as co-localization with markers of clathrin- and caveolae-dependent pathways. The AuPEI-NPs polyplexes use preferentially the more efficient caveolae internalization pathway to promote transfection, fact that supports their higher transfection efficiency compared to Lipofectamine 2000. In addition, intracellular trafficking of the AuPEI-NPs can be study by Transmission Electron Microscopy.