Figure 5.

Remote loading approach of DOX into the intraliposomal aqueous phase. Liposomes are prepared at the desired concentration of ammonium sulphate. The gradient was formed by removing the ammonium sulphate from the external liposome medium. Intraliposomal NH₄⁺ dissociates into NH₃ and H⁺, NH₃ escape from the liposome and H⁺ is retained in the liposome water phase. DOX HCl is added to the liposome dispersion at a temperature above the phase transition of the liposomal lipids. DOX, a cationic amphiphile, is present in equilibrium between an ionised and a non-ionised form. The latter form commutes across the liposome bilayer and becomes ionised once exposed to the internal H⁺ environment, and forms a salt with the SO₄²⁻ anions.