Cubosomes: a promising vesicular system for drug delivery

Over the last 30 years, there has been a tremendous increase in research on the use of lipid nanoparticles in the production of nanocarriers for drug delivery and biomedical imaging. The attraction of lipid nanoparticles (LNPs) for therapeutic and diagnostic applications is based on their capacity to load therapeutic and diagnostic substances, preserve them from degradation, improve absorption and intracellular penetration of the carried entity, adjust pharmacokinetics, reduce systemic toxicity, and overcome physiological barriers, just to cite their main features. Moreover, by means of various surface alteration methodologies, surface engineering on LNPs can be used to achieve active drug targeting. These characteristics make LNPs really appealing for loading sparingly water-soluble medicines with low bioavailability, poor pharmacokinetics, or different negative side effects. As a consequence of the hydrophobic effect, the self-assembly of amphiphilic lipids can result into different thermodynamically stable and weakly water soluble structures, recognized as lyotropic liquid crystalline (LLC) systems (i.e., lamellar, hexagonal, or bicontinuous cubic phases). Among the extensive family of LNPs obtainable from these structures, in this chapter we will focus on recent achievements of cubosomes as drug delivery agents. Firstly presented by Larsson and coworkers, cubosomes are a particular kind of lipid nanovesicles (NVs) produced by dispersion of a bicontinuous cubic phase LLC in water, with size ranging from 100 to 300 nm. The lipophilic bicontinuous cubic phase in cubosomes is able to create a thermodynamically stable three-dimensional (3D) network that keeps separate two distinct continuous, but non intersecting, hydrophilic regions. As a result, both water insoluble and soluble compounds can be loaded into these structures, either dissolved within the lipophilic 3D structure or adsorbed inside the hydrophilic channel walls, respectively.