Development of non-ionic surfactant vesicles as drug delivery vehicles

The molecular architecture of vesicles formed by the phospholipid-like non-ionic surfactant, 1,2 diooctadecyI-rac-glycerol-3-omega)-methoxydodecyIethylene glycol (abbreviated as 2C(18)E(12),), has been established using a combination of small angle neutron scattering and neutron specular reflection measurements. These studies showed that the bilayer formed by 2C(n)E(m) is different in structure to that formed by phospholipids (in particular distearylphosphatidylcholine (DSPQ), with the same hydrocarbon chain lengths) in that there is considerable intermixing of the hydrophilic and hydrophobic regions of the non-ionic surfactant. In addition the thickness and bilayer repeat distance of the vesicles formed by 2C(n)E(m) is influenced by the presence of electrolyte to a greater extent than is seen with DSPC. These structural differences explain why the vesicles formed by 2C(n)E(m) are more permeable to entrapped water-soluble solutes than those prepared from DSPC.