Cubic-to-inverted micellar and the cubic-to-hexagonal-to-micellar transitions on phytantriol-based cubosomes induced by solvents

Small-angle X-ray and neutron scattering applied to lipid-based nanoparticles: Recent advancements across different length scales

Lipid-based nanoparticles (LNPs), ranging from nanovesicles to non-lamellar assemblies, have gained significant attention in recent years, as versatile carriers for delivering drugs, vaccines, and nutrients. Small-angle scattering methods, employing X-rays (SAXS) or neutrons (SANS), represent unique tools to unveil structure, dynamics, and interactions of such particles on different length scales, spanning from the nano to the molecular scale. This review explores the state-of-the-art on scattering methods applied to unveil the structure of lipid-based nanoparticles and their interactions with drugs and bioactive molecules, to inform their rational design and formulation for medical applications. We will focus on complementary information accessible with X-rays or neutrons, ranging from insights on the structure and colloidal processes at a nanoscale level (SAXS) to details on the lipid organization and molecular interactions of LNPs (SANS). In addition, we will review new opportunities offered by Time-resolved (TR)-SAXS and -SANS for the investigation of dynamic processes involving LNPs. These span from real-time monitoring of LNPs structural evolution in response to endogenous or external stimuli (TR-SANS), to the investigation of the kinetics of lipid diffusion and exchange upon interaction with biomolecules (TR-SANS). Finally, we will spotlight novel combinations of SAXS and SANS with complementary on-line techniques, recently enabled at Large Scale Facilities for X-rays and neutrons. This emerging technology enables synchronized multi-method investigation, offering exciting opportunities for the simultaneous characterization of the structure and chemical or mechanical properties of LNPs.

A short review on the applicability and use of cubosomes as nanocarriers

Abstract

Cubosomes are nanostructured lipid-based particles that have gained significant attention in the field of drug delivery and nanomedicine. These unique structures consist of a three-dimensional cubic lattice formed by the self-assembly of lipid molecules. The lipids used to construct cubosomes are typically nonionic surfactants, such as monoolein, which possess both hydrophilic and hydrophobic regions, allowing them to form stable, water-dispersible nanoparticles. One of the key advantages of cubosomes is their ability to encapsulate and deliver hydrophobic as well as hydrophilic drugs. The hydrophobic regions of the lipid bilayers provide an ideal environment for incorporating lipophilic drugs, while the hydrophilic regions can encapsulate water-soluble drugs. This versatility makes cubosomes suitable for delivering a wide range of therapeutic agents, including small molecules, proteins, peptides, and nucleic acids. The unique structure of cubosomes also offers stability and controlled release benefits. The lipid bilayers provide a protective barrier, shielding the encapsulated drugs from degradation and improving their stability. Moreover, the cubic lattice arrangement enables the modulation of drug release kinetics by varying the lipid composition and surface modifications. This allows for the development of sustained or triggered drug release systems, enhancing therapeutic efficacy and reducing side effects. Furthermore, cubosomes can be easily modified with targeting ligands or surface modifications to achieve site-specific drug delivery, enhancing therapeutic selectivity and reducing off-target effects. In conclusion, cubosomes offer a versatile and promising platform for the delivery of therapeutic agents. In this manuscript, we will highlight some of these applications.

Graphical abstract

Cubosomes as an emerging platform for drug delivery: a state-of-the-art review

Lipid-based drug delivery nanoparticles, including non-lamellar type, mesophasic nanostructured materials of lyotropic liquid crystals (LLCs), have been a topic of interest for researchers for their applications in encapsulation of drugs...

The effect of headgroup methylation on polymorphic phase behaviour in hydrated N-methylated phosphoethanolamine:palmitic acid membranes

Mixtures of fatty acids and phospholipids can form hexagonal (HII) and inverse bicontinuous cubic phases, the latter of which are implicated in various cellular processes and have wide-ranging biotechnological applications in protein crystallisation and drug delivery systems. Therefore, it is vitally important to understand the formation conditions of inverse bicontinuous cubic phases and how their properties can be tuned. We have used differential scanning calorimetry and synchrotron-based small angle and wide angle X-ray scattering (SAXS/WAXS) to investigate the polymorphic phase behaviour of palmitic acid/partially-methylated phospholipid mixtures, and how headgroup methylation impacts on inverse bicontinuous cubic phase formation. We find that upon partial methylation of the phospholipid headgroup (1 or 2 methyl substituents) inverse bicontinuous cubic phases are formed (of the Im3m spacegroup), which is not the case with 0 or 3 methyl substituents. This shows how important headgroup methylation is for controlling phase behaviour and how a change in headgroup methylation can be used to controllably tune various inverse bicontinuous phase features such as their lattice parameter and the temperature range of their stability.

Additives-directed lyotropic liquid crystals architecture: Simulations and experiments

In this study, alkanes and sucrose esters are employed to investigate the influence of additives on lyotropic liquid crystal architecture. After molecular dynamic simulations and experiment characterization, we showed how the additives control the structure of LLCs. By controlling the polarity of additives, the phase behavior of LLCs can be engineered to form the required structure. Dissipative particle dynamics (DPD) is introduced for simulating the self-assembly of phytantriol (PT), providing intuitionistic images and structure information, which shows that additives with low-polarity complicate the internal structure of liquid crystal systems. Then the ternary phase diagrams of additives, PT, and water are constructed to systematically study the effects of additives on the phase behavior of LLCs. Consistent with DPD simulation results, there is a certain regularity in the effects of additives on the structure of liquid crystals. The difference in the structure of LLCs is due to the variability in the critical packing parameter (CPP) obtained by changing the polarity of additives. Our findings demonstrate that additives polarity is a key factor in LLCs structure, and may pave a promising avenue for novel LLCs development and translation, determining the self-assembly process and the resulting phase of LLCs.