Construction and deconstruction of PLL/DNA multilayered films for DNA delivery: effect of ionic strength

Through the layer-by-layer (LbL) self-assembly technique, DNA was incorporated into the multilayered films with poly-l-lysine (PLL). The effect of ionic strength on the construction and deconstruction of the PLL/DNA films was investigated. It was found that the salt concentration of the deposition solution had a significant effect on the construction of the films, which might attribute to the effect of salt ions on the conformation of polyelectrolytes and interaction between PLL and DNA molecules. A salt-induced deconstruction of the PLL/DNA films was observed. The extent of the deconstruction increased with the salt concentration in the incubation solution. The mechanism of the deconstruction was discussed. Taking the advantages of the LbL technique, the erasable PLL/DNA films could deposit onto a variety of surfaces, such as vascular stent, intervention catheter and tissue engineering scaffold, to serve as a novel DNA delivery system.