Gold/cationic polymer nano-scaffolds mediated transfection for non-viral gene delivery system

Gene delivery scaffolds based on DNA plasmid condensation with colloidal gold/cationic polymer were developed. The synthesized gold nanoparticles displayed spherical shape with an average size of 12 nm under observation with a transmission electron microscope. Gold/cationic polymer nano-scaffolds were formed though electrostatic interaction yielding gold/polyethyleneimine (PEI), gold/chitosan and gold/chitosan/PEI complexes. Luciferase-encoding plasmid DNA was subsequently added and adsorbed on the prepared scaffolds to be used as a non-viral gene carrier. Physicochemical properties of DNA-binding scaffolds were examined including size and zeta potential. The results indicated that the sizes of gold/polymer based scaffolds were generally less than 400 nm, and they carried positive charge on their surfaces. Gel retardation assay and atomic force microscopy confirmed the condensation of plasmid DNA on gold/polymer based scaffolds. Confocal fluorescent microscopy verified the presence of DNA in the cell using gold nano-scaffold as a carrier. Transfection efficiency assay using A549 and HeLa human cell lines revealed that gold/polymer based nano-scaffolds provided transfection efficiency approximately 10 times higher than polymeric-based gene carriers. This study proposed simple and practical approach, having the potential for use as an alternative gene carrier in non-viral gene delivery system.