Layer-by-layer assembly of cationic lipid and plasmid DNA onto gold surface for stent-assisted gene transfer

Intravascular stent-assisted gene transfer is an advanced approach for the therapy of vascular diseases such as atherosclerosis and stenosis. This approach requires a stent that allows local and efficient administration of therapeutic genes to the target cells at the vascular wall. To create such a stent, a method was developed for loading plasmid DNA onto the metal surface. The method involves the formation of self-assembled monolayer on the noble metal surface followed by electrostatic layer-by-layer (LBL) assembly of a cationic lipid/plasmid DNA complex and free plasmid DNA. In this in vitro feasibility study, the thin plainer film and the wire of gold were used as a substrate. The LBL assembly process was characterized by surface plasmon resonance spectroscopy and static contact angle measurement. Plasmid DNA loaded in the multilayer exhibited improved resistance against nuclease digestion. When cultured directly on the DNA-loaded surface, cells were transfected to express exogenous gene in the DNA loading-dependent manner. Plasmid DNA could also be transferred to endothelial cells from its apical side by placing the DNA-loaded gold wire onto the cell layer.