Abstract:

The dielec. behavior of the insulin-loaded HII mesophase (contg. GMO-TAG-water-glycerol-insulin) was studied using two empty ref. systems (GMO-TAG-water and GMO-TAG-water-glycerol) at a frequency range of 10-2-106 Hz, and a temp. range of 290-333 K. Three clearly defined relaxation processes were obsd. and assigned to the reorientation of GMO polar heads, the tangential movement of counterions at the interface, and the movements of TAGs through the lipid tail. Upon addn. of glycerol, a heterogeneous inner structure was formed within the HII cylinders: the water-glycerol core surrounded by a water rigid layer. Upon heating, two crit. points were detected referring to the dehydration of the GMO heads (at 304 K, similar to the water-filled HII system) and to energetic modifications (at 316 K), resulting in breaking of the water layer allowing on-demand controlled release. Insulin incorporation combined the features of both ref. HII systems. Yet, unlike the empty HII systems, insulin perturbed the GMO-water interface while decreasing the movement of the GMO headgroup, and reducing T0 (296 K). No interactions were formed between the dipole of each counterion at the interface region and the matrix (the GMO), fitting the Debye process. Dynamic behavior was obsd., pointing to mobility between the hexagonal rods themselves, enabling controlled release from the HII carrier. [on SciFinder(R)]