Abstract
Novel potential carriers for non-invasive drug delivery were prepared from polyoxyethylene(20) oleyl ether (C18:1EO20) and soybean phosphatidylcholine (SPC) in different relative molar ratios, Re; this produced stiff SPC liposomes (2rves∼120 nm) at one end and much smaller (2rmic ≤ 15 nm), comparably non-deformable, mixed micelles at the other end of aggregate spectrum. Deformability of the mixed amphiphat vesicles (2rv∼105 nm) existing in-between increases with Re non-linearly, up to a quasi-plateau at Re ≥ = 0.25 in the bilayer. The surfactant-saturated bilayers exhibit bending rigidity of κc∼2.1 kBT, as determined with an improved vesicle adaptability assay involving analysis of normalised flux density through a nano-porous barrier as an activated transport process. Pore penetrability vs. driving pressure data measured with the mixed amphiphat vesicles resemble results of computer simulation of deformable vesicles penetrating a constriction [Gompper G, Kroll DM. 1995. Driven transport of fluid vesicles through narrow pores. Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 52:4198-4208], confirming basic similarity of both processes. The improved assay can reveal partial lipid solubilisation at Re>, which is linearly proportional to Re − . C18:1EO20-SPC mixed vesicles that can cross narrow pores are arguably suitable for targeted drug delivery across intact skin.
Notes
1. The latter binds to phosphatidylcholine, resulting in a complex with surfactant-like properties (Cevc Citation2004).
3. The best amongst simple descriptors of the double-bond effect magnitude is the maximum number of double bonds per fatty chain in each lipid molecule, nC = C,max—so long as nC = C,max < 3—as this parameter in the first approximation determines bilayer thickness that affects bilayer rigidity with the second power.
2. Some of the values reported earlier for EPC are higher: κc < 35 kBT, with an average value of 21.9 kBT, but there is a tendency towards lower values in the more recent papers (Petrov Citation1999).