Abstract:

The structural, dynamic, and kinetic aspects of the HII systems based on glycerol monooleate (GMO), phosphatidylcholine (PC), triacylglycerol (TAG), and water were investigated by dielec. spectroscopy in a frequency range of 10-2-106 Hz, and a temp. range of 290-320 K. Three distinct processes as well as a temp.-activated dc cond. were detected and examd. These were assigned to the reorientation of the GMO polar heads, the tangential movement of counterions at the interface, the transport of TAGs through the lipids tails, and the ion mobility within the water cylinders. Upon addn. of PC, the crit. temp. (T0) of the dehydration of the GMO headgroups increased. The optimal concn. found for structural stabilization of the HII mesophase was 10 wt% PC, since it imparted the strongest bonding at the interfacial layer and increased the assocn. between the lipid tails. Within the HII cluster, TAG percolated and shifted between the hexagonal rods themselves. The present study demonstrated the benefit of controlling the crit. temp. of the HII mesophase partial dehydration and softening, as well as the percolation of TAGs. These factors influence the diffusion mode of embedded drugs in the physiol. temp. range. [on SciFinder(R)]