Characterization of Lipid-Based Lyotropic Liquid Crystal and Effects of Guest Molecules on Its Microstructure: a Systematic Review

Abstract

Liquid crystals (LCs) are conventionally divided into thermotropic or lyotropic, based on the organization and sequence of the controlled molecular system. Lipid-based lyotropic liquid crystal (LLC), such as lamellar (Lα), bicontinuous cubic (Q), or hexagonal (H) phases, have attracted wide interest in the last few decades due to their practical potential in diverse applications and notable structural complexity. Various guest molecules, such as biopharmaceuticals, chemicals, and additives, can be solubilized in either aqueous or oily phase. And the LLC microstructure can be altered to affect the rate of drug release eventually. To utilize these microstructural variations to adjust the drug release in drug delivery system (DDS), it is crucial to understand the structure variations of the LLC caused by different types of guest molecules. Therefore, in this article, we review the effect of guest molecules on lipid-based LLC microstructures. In particular, we focus on the different characterization methods to evaluate this change caused by guest substances, such as polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), self-diffusion nuclear magnetic resonance (SD-NMR), and so on.

Lubrication and Dynamically Controlled Drug Release Properties of Tween 85/Tween 80/H2O Lamellar Liquid Crystals

“…23 As the concentration of Tween 80 increased and the water content decreased, the rod micelles gradually accumulated into hexagonal liquid crystals 19 when the concentration of Tween 80 was larger than 48%, the polarized texture showed an irregular fuzzy texture (Figure 1c). 24 While the packing parameter of Tween 85 is more than 1/3, spherical micelles are generated at concentrations higher than CMC (2.9 × 10 −4 mM, ∼5.33 × 10 −7 wt %). 25 With increasing concentrations of Tween 85, the spherical micelles transformed into vesicles (Figure S1a), and the diameter of the vesicles increased gradually (Figure S1b).…”

A Novel Phytantriol-Based Lyotropic Liquid Crystalline Gel for Efficient Ophthalmic Delivery of Pilocarpine Nitrate

“…It is universally known that the Q II phase consists of two interlaced networks of water channels and is linked in a threedimensional space with mesophase symmetry, spaced by the lipid bilayers. Moreover, they are composed of two independent, uninterrupted but noninteracting hydrophilic regions divided by a lipid bilayers that is twisted into a periodic minimum surface with zero mean curvature (50). Accordingly, the hydrophilic drug PN embedded into the polar headgroup of the Q II phase would easily diffuse from the matrix (Fig.…”

Vertical Alignment of Liquid Crystal on Sustainable 2,4-Di-tert-butylphenoxymethyl-Substituted Polystyrene Films

“…Lyotropic LCs (or lyomesophases) consisting of amphiphiles have a tendency to form self-assembled structures depending on their concentration in solution. The physicochemical properties of lyotropic LCs and their intrinsic structures, including lamellar, hexagonal, and cubic phases, make them suitable as drug delivery agents in pharmaceutical sciences in a wide range of applications [ 11 , 12 , 13 , 14 , 15 , 16 ]. In particular, the hexagonal and cubic phases are of high interest in the field of drug delivery agents owing to their ability to control or maintain the release of hydrophilic and hydrophobic drug molecules with a wide range of molecular weights [ 17 , 18 , 19 ].…”