Cell interactions with lipid nanoparticles possessing different internal nanostructures: Liposomes, bicontinuous cubosomes, hexosomes, and discontinuous micellar cubosomes

Hypothesis: Lyotropic liquid crystalline nanoparticles (LLCNPs) with complex internal nanostructures hold promise for drug delivery. Cubosomes, in particular, have garnered interest for their ability to fuse with cell membranes, potentially bypassing endosomal escape challenges and improving cellular uptake. The mesostructure of nanoparticles plays a crucial role in cellular interactions and uptake. Therefore, we hypothesise that the specific internal mesophase of the LLCNPs will affect their cellular interactions and uptake efficiencies, with cubosomes exhibiting superior cellular uptake compared to other LLCNPs. Experiments: LLCNPs with various mesophases, including liposomes, cubosomes, hexosomes, and micellar cubosomes, were formulated and characterised. Their physicochemical properties and cytotoxicity were assessed. Chinese Hamster Ovarian (CHO) cells were treated with fluorescently labelled LLCNPs, and their interactions were monitored and quantified through confocal microscopy and flow cytometry. Findings: The non-lamellar LLCNPs showed significantly higher cellular interactions compared to liposomes, with cubosomes exhibiting the highest level. However, there was no significant difference in relative cell uptake between cubosomes, hexosomes, and micellar cubosomes. Cell uptake experiments at 4 °C revealed the presence of an energy-independent uptake mechanism. This study provides the first comparative analysis of cellular interactions and uptake efficiencies among LLCNPs with varying mesophases, while maintaining similar size, composition, and surface charge.