The dielectric study of insulin-loaded reverse hexagonal (H_II) liquid crystals

Abstract

The dielectric behavior of the insulin-loaded HII mesophase (containing GMO-TAG-water-glycerol-insulin) was studied using two empty reference systems (GMO-TAG-water and GMO-TAG-water-glycerol) at a frequency range of 10(-2)-10(6) Hz, and a temperature range of 290-333 K. Three clearly defined relaxation processes were observed 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 addition 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 critical 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 reference 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 observed, pointing to mobility between the hexagonal rods themselves, enabling controlled release from the HII carrier.

Topological Influence of Lyotropic Liquid Crystalline Systems on Excited-State Proton Transfer Dynamics

“…54 However, H II phase consists of densely packed inverted micelles in hexagonal cylindrical fashion (Scheme 1). 18 Thus, from the geometrical architectures, it is clear that H II phase provides most restricted pathway for the proton during "Grotthuss" mechanism of proton diffusion. However, the diamond Pn3m phase can provide the faster pathway for proton diffusion due to tetrafold water channel connectivity, rather than trifold connectivity in Ia3d phase.…”

“…Each cylinder of H II phase is a topologically inverted “water-in-oil” version, where the aqueous domain is densely packed infinitely long, water filled straight rods (Scheme ). However, Ia3d (gyroid type) and Pn3m (diamond type) phases exhibit inverse (type II) and bicontinuous structure. These inverse bicontinuous structures of both cubic phases adopt “minimal surface” (mean curvature is zero), which is extended to fill space periodically in different modes (gyroid mode in Ia3d and diamond mode in Pn3m) .…”

Impact of Topology on the Characteristics of Water inside Cubic Lyotropic Liquid Crystalline Systems

“…The fluid lamellar phase consists of amphiphilic bilayers separated by water domains and closely resembles the cellular membranes . The H II phase is a topologically inverted “water in oil” system comprising infinitely long and straight water filled rods packed densely in a nonpolar matrix of lipophilic chains. , The inverse bicontinuous cubic phases, namely, gyroid ( Ia 3 d ) and diamond ( Pn 3 m ), are formed by the arrangement of a continuous lipid bilayer on mathematical minimal surfaces (Scheme ). , In Ia 3 d mesophase, two water networks join in a 3 × 3 junction at an angle of 120°, and in Pn 3 m , they join in a 4 × 4 manner at a tetrahedral angle of 109.5° .…”

Solvation Dynamics in Different Phases of the Lyotropic Liquid Crystalline System

“…Because of its unique structural properties, H II mesophase has been used as an excellent carrier for important drug molecules such as Desmopressin, sodium diclofenac, , and cyclosporine A . Moreover, due to excellent biocompatibility of H II mesophase, it provides the new opportunities to deliver biomolecules such as insulin, , lysozyme, peptides, proteins, and DNA , to their active sites. Furthermore, it was found that the inner diameter of the water cylinder is sufficient to load the hydrophilic dendrimer, which might have potential application for dendrimer coupled drug delivery vehicles …”