Journal of Physical Chemistry B, Vol.121, No.17, 4482-4491, 2017
Cavity Orientation Regulated by Mixture Composition and Clustering of Amphiphilic Cyclodextrins in Phospholipid Monolayers
Artificial supramolecular-hierarchical structures that emulate nature represent an overcoming alternative for the design of new drug delivery systems. Thermodynamic and topographic properties of films formed by a monoacylated amphiphilic,beta-cyclodextrin (beta CD-C16) with the phospholipid 1-palmitoy1-2oleoyl-sn-glycero-3-phosphocholine (POPC) at the air/water interface were studied. beta CD-C16 formed stable mixed films with POPC at several proportions when spread together at the air/water interface. The orientation of beta CD-C16 cavity at the interface depends on its mole fraction in the film as reveled by the analysis of partial mean molecular areas as a function of composition. Furthermore, beta CD-C16 was able to penetrate POPC preformed films in a broad range of initial surface pressures, including that near the collapse pressure of the phospholipid. These results demonstrated the strong tendency of beta CD-C16 to be inserted into this lipid matrix commonly used in liposome formulations. Topography studies show that beta CD-C16 segregate from POPC forming clusters enriched in beta CD-C16. Segregation of beta CD-C16 was especially noticeable when beta CD-C16 were incorporated by themselves into a preformed POPC matrix leading to ordered and highly birefringent structures that suggest the formation of hierarchical stacked beta CD-C16 arrangement at the interface.