Molecular organization and recognition properties of amphiphilic cyclodextrins.

RITA H. DE ROSSI; O FERNANDO SILVA; RAQUEL VICO; CARLOS GONZALEZ

PURE AND APPLIED CHEMISTRY

INT UNION PURE APPLIED CHEMISTRY

Año: 2009 vol. 81 p. 755 - 765

0033-4545

The continuing challenge of using cyclodextrins (CDs) for solubilization and drugtargeting has led to the preparation of a wide variety of chemically modified derivatives inorder to improve the properties of these host molecules. A possible approach for pharmaceuticalapplications would be to combine the recognition specificity of CDs with the transportproperties of organized structures such as vesicles, liposomes, or micelles.Amphiphilic CDs can be admixed to phospholipid monolayers and to liposomes, andthey can be dispersed into nanospheres showing promising properties for drug encapsulation.Monoacylated derivatives of b-CD, Mod-CD (Cn), were synthesized in our laboratoryfrom the reaction of alkenyl succinic anhydride with b-CD. We found that the compoundwith 10 carbon atoms in the alkenyl chain, Mod-CD (C10), can be incorporated into invertedmicelles. We studied their properties in solution and at the air–water interface. In solutionthey have very low critical micellar concentration, and in the aggregates there are two recognitionsites: one is the cavity of the CD and the other is formed by the hydrophobic tails. Thealkenyl chain interacts with the cavity, but this is not an obstacle for the association with externalguests such as 1-amino adamantane, phenolphthalein, or Prodan.Mod-CD (Cn) with n equal to 10, 14, and 16 (n indicates the number of carbons in thealkenyl chain), form stable monolayers at the air–water interface and they adopt an organizationvery different from those found for persubstituted CDs. The differences are attributedto the higher conformational flexibility of these compounds, which allows the organizationof the CD units with the cavity perpendicular to the interface.