Liquid crystalline system for drug delivery: structural insights, preparation techniques and translational potential

Liquid Crystals (LCs) constitute a versatile class of soft materials whose combination of molecular order and fluidity enables the creation of nanostructured drug-delivery systems with precisely tunable properties. This review provides a unified and application-oriented evaluation of thermotropic and lyotropic liquid crystal systems, emphasizing how their self-assembly, curvature behavior, and interfacial energetics govern mesophase formation and drug-loading capacity. Particular focus is placed on the biodegradability, biocompatibility, and structural robustness of LC matrices, as these parameters critically determine safety and sustained-release performance. Key preparation strategies, including high-energy top-down dispersion, low-energy bottom-up assembly, and precursor-based methods, are examined alongside characterization tools such as polarized optical microscopy, small-angle X-ray scattering, and dynamic light scattering. The ability of LC nanocarriers to encapsulate both hydrophilic and hydrophobic drugs, minimize burst release, and deliver controlled diffusion through cubic, hexagonal, and lamellar architectures is highlighted. Their high entrapment efficiency, extended-release kinetics, and inherent colloidal stability position these systems as promising candidates for improving the delivery of poorly soluble therapeutics. The review further synthesizes insights into phase transitions, dilution responses, and stimuli-responsive behaviors that enable on-demand or site-specific release. Scalability, compatibility with low-energy processing, and stability under physiological conditions support their translational relevance. Unlike earlier reviews, this article integrates structural phase physics, formulation engineering, and translational evidence into a unified framework, contrasting cubic, hexagonal, and lamellar systems across preparation routes, stimuli responsiveness, release behavior, toxicology, and clinical progress to provide an up-to-date, application-oriented perspective for LC-based nanomedicine.