Structural investigation and steric stabilisation of Guerbet glycolipid-based cubosomes and hexosomes using triblock polyethylene oxide-polypropylene oxide-polyethylene oxide copolymers

Abstract

Aqueous dispersions of inverse nonlamellar liquid crystalline nanostructures namely cubosomes and hexosomes have been used as carriers for drug delivery. The large surface area and internal water channel networks in these nanocarriers make them useful to transport amphiphilic, hydrophilic and hydrophobic active ingredients. However, suitable stabilisers that can maintain the colloidal stability and preserving the internal structures of the complex cubosomes and hexosomes are integral. Herein, Guerbet glycolipids namely 2-hexyl-decyl-β-D-glucopyranoside (β-Glc-OC10C6) and 2-hexyl-decyl-β-D-xylopyranoside (β-Xyl-OC10C6) were investigated for their potential in forming cubosomes and hexosomes respectively using Pluronic copolymers as steric stabilisers. The performance of five different Pluronics was evaluated for stabilisation of the dispersions, with a view to establish a structure-property relationship between the lipids and the stabilisers. The dispersions were assessed through synchrotron small-angle X-ray scattering as a function of temperature and the concentration of stabilisers. The internal structure of dispersed particles of β-Glc-OC10C6 was susceptible to changes upon stabilisation by different Pluronics and with increasing temperature. The lowest molecular weight Pluronic studied, L64, had the greatest propensity to disrupt the structure, suggesting that it is able to penetrate the internal structure to a greater degree than the other Pluronic stabilisers. In contrast, the β-Xyl-OC10C6 counterpart formed a stable inverse hexagonal phase structure that was invariant with the Pluronic used or temperature. The stability of the structure of β-Xyl-OC10C6 suggests it has greater potential for use in drug delivery applications and the studies overall extend the current understanding around the structures formed upon dispersion of Guerbet lipids.