Zinc-Chelated Poly(1-vinylimidazole) and a Carbohydrate Ligand Polycation Form DNA Ternary Complexes for Gene Delivery

Zinc-chelated poly(1-vinylimidazole) (PVIm-Zn) and a carbohydrate ligand polycation, a poly(l-lysine) conjugated with lactose molecules (PLL-Lac), have formed DNA ternary complexes for gene delivery. The particle size of the PVIm-Zn/DNA complexes with negative zeta potential was decreased by the addition of the PLL-Lac. The resulting PLL-Lac/PVIm-Zn/DNA ternary complexes, which exhibited the pH-dependent dissociation of the PLL-Lac, mediated more gene expression than the PVIm/DNA binary complexes. The PLL-Lac/PVIm-Zn/DNA complexes with the specific recognition of cell surface receptors mediated the highest gene expression without cytotoxicity at a relatively lower charge ratio (positive/negative = 2.5). These results suggest that the pH-dependent dissociation of the carbohydrate ligands after the recognition of cell surface receptors, including the physicochemical and biochemical function of PVIm-Zn, played an important role in gene expression.