There are three methods of non-viral DNA transfer. Though not very efficient, this can result in prolonged low level expression in vivo.
Liposomes are lipid bilayers entrapping a fraction of aqueous fluid.
By including a small amount of an anionic lipid in an otherwise cationic liposome the DNA can be incorporated into the internal surface of the liposome, thus protecting it from enzymatic degradation. The Sendai virus additionally allows the plasmid DNA to escape from the endosome into the cytoplasm, thus avoiding degradation. Molecular conjugates consist of protein or synthetic ligands to which a DNA binding agent has been attached. Delivery to the cell can be improved by using similar techniques to those for liposomes.