Layer-by-layer deposition of cationic polymers on gold nanoparticle for non-viral gene delivery system

In this study, gold nanoparticles displayed spherical shapes with an average size of 12 nm were synthesized. The nano-carriers for gene delivery were subsequently developed based on DNA adsorption on the gold/cationic polymer-scaffold. The multilayer nanoparticles of gold, chitosan derivative (MPyMeChC), polyethyleneimine (PEI) and DNA were generated via layer-by-layer (LbL) depositing on gold-scaffolds. The LbL of gold-based scaffold were prepared via electrostatic interaction yielding gold/MPyMeChC/DNA (G/C/D) and gold/MPyMeChC /DNA/PEI (G/C/D/P) complexes. Size and zeta potential of DNA-bound scaffolds were examined. The results indicated that the sizes of G/C/D and G/C/D/P were less than 400 nm with positively charged on their surfaces. Atomic force microscopy confirmed the condensation of plasmid DNA on gold/polymer based scaffolds. Transfection efficiency and cell viability assay were examined on HeLa human cell lines. The result revealed that transfection via G/C/D and G/C/D/P provided transfection efficiency approximately 10- and 10(3)- times higher than conventional C/D polyplex. However, the cell survival decreased slightly compared to C/D transfection system. Confocal fluorescent microscopy verified the presence of DNA in Hela cell after transfection though G/C/D and G/C/D/P. This study proposes the simple and practical approach for preparation a nano-carrier for gene delivery through layer-by-layer deposition of cationic polymers on gold nanoparticle.