Cavity Orientation Regulated by Mixture Composition and Clustering of Amphiphilic Cyclodextrins in Phospholipid Monolayers

Abstract

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 β-cyclodextrin (βCD-C16) with the phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) at the air/water interface were studied. βCD-C16 formed stable mixed films with POPC at several proportions when spread together at the air/water interface. The orientation of βCD-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, βCD-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 βCD-C16 to be inserted into this lipid matrix commonly used in liposome formulations. Topography studies show that βCD-C16 segregate from POPC forming clusters enriched in βCD-C16. Segregation of βCD-C16 was especially noticeable when βCD-C16 were incorporated by themselves into a preformed POPC matrix leading to ordered and highly birefringent structures that suggest the formation of hierarchical stacked βCD-C16 arrangement at the interface.

Cyclodextrin modified niosomes to encapsulate hydrophilic compounds

“… 48 However, the mechanism of particle size reduction by cyclodextrins is unclear and in literature to date are reflected the difficulties to demonstrate, in a direct way, structural evidence that show the location of CDs in surfactants assemblies. 49 With regards to the mentioned above, we explained our results considering that the modified cyclodextrin could anchor at the surface of niosomes penetrating in the layer through the hydrophobic chain 50 and due the insertion in the outer layer and the presence of cyclodextrin moiety, the area of polar headgroup at the interphase increase and alters the radius of curvature, and thus a decreasing in the size of niosomes was observed. Table 1 also shows that PDI values obtained for all niosomes were equal or lower than 0.5, which indicate that the vesicles are monodisperse.…”

Phenolic Pollutant Uptake Properties of Molecular Templated Polymers Containing β-Cyclodextrin

“…T-polymers possess a linear morphology that favors hydrogen bonding between polymer units that contribute to fibril formation. 10,49 The formation of granular structures is consistent with the globular morphology of NT-polymers and the tendency of such systems to undergo nonspecific aggregation that differs from the fibrillike morphology of the T-polymers. The trends observed for the SEM results provide evidence that templation and nontemplation leads to polymers with variable morphology, in agreement with the results reported by Koopmans and Ritter.…”