Studies on the Interactions of 2-Hydroxyoleic Acid with Monolayers and Bilayers Containing Cationic Lipid: Searching for the Formulations for More Efficient Drug Delivery to Cancer Cells.

Drug delivery in cationic liposomes seems to be a promising therapeutic approach in cancer treatment. The rational design of the positively charged lipid vesicles as anticancer drug carriers should be supported by a detailed analysis of the interactions of the carrier components with anticancer drugs. In the present work, 2-hydroxyoleic acid (2OHOA; Minerval), a membrane lipid therapy drug, was incorporated into positively charged mono- and bilayer membranes containing 1-palmitoyl-2-oleoyl- sn-glycero-3-ethylphosphocholine (EPOPC), the synthetic cationic lipid, and 1,2-dioleoyl- sn-glycero-3-phosphocholine (DOPC). The intermolecular interactions, fluidity, and miscibility of the studied monolayers were analyzed by utilizing Langmuir balance experiments. The morphology of two-dimensional films was inspected using a Brewster angle microscopy technique. The properties of the liposomes were investigated by dynamic light scattering (DLS) and zeta potential measurements, steady-state fluorescence anisotropy experiments, and the spectrofluorimetric titration of calcein-encapsulated vesicles with a lysis-inducing agent. According to the collected results, 2OHOA intercalation into films of pure phospholipids or a binary EPOPC/DOPC film is thermodynamically favorable. Surprisingly, no significant effect of the presence of unsaturated 2OHOA chains on the EPOPC/DOPC monolayer order was observed. The experiments carried out for 2OHOA-inserted cationic EPOPC/DOPC (1:4) liposomes indicate effective incorporation of the drug into the liposome bilayer and the formation of stable vesicles without affecting their properties markedly. On the basis of the obtained results, EPOPC/DOPC/2OHOA cationic liposomes with 15% 2OHOA content in the phospholipid bilayer seem to be the most suitable for potential biomedical applications.