The aim of the present work is to gain an understanding of the interaction of DNA with the phospholipid bilayers. The effect of different forms of DNA, the presence of divalent cations, such as calcium and the presence of a membrane potential will be investigated. Neutron reflectivity experiments are proposed to determine whether the binding of DNA to zwitterionic lipids, in the presence of calcium, is affected by the presence of a bilayer and transbilayer potential. We will be able to create a transbilayer potential by varying the voltage applied to an electrode, allowing the effect of the bilayer potential on DNA binding to be assessed. The information gained through these studies will aid in our understanding of the interaction of DNA with bilayers that have physiologically-relevant potential with a view to improving the design of gene delivery vesicles.