Molecular organization and recognition properties of amphiphilic cyclodextrins

Abstract

The continuing challenge of using cyclodextrins (CDs) for solubilization and drug targeting has led to the preparation of a wide variety of chemically modified derivatives in order to improve the properties of these host molecules. A possible approach for pharmaceutical applications would be to combine the recognition specificity of CDs with the transport properties of organized structures such as vesicles, liposomes, or micelles. Amphiphilic CDs can be admixed to phospholipid monolayers and to liposomes, and they can be dispersed into nanospheres showing promising properties for drug encapsulation. Monoacylated derivatives of β-CD, Mod-CD (Cn), were synthesized in our laboratory from the reaction of alkenyl succinic anhydride with β-CD. We found that the compound with 10 carbon atoms in the alkenyl chain, Mod-CD (C10), can be incorporated into inverted micelles. We studied their properties in solution and at the air-water interface. In solution they have very low critical micellar concentration, and in the aggregates there are two recognition sites: one is the cavity of the CD and the other is formed by the hydrophobic tails. The alkenyl chain interacts with the cavity, but this is not an obstacle for the association with external guests 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 the alkenyl chain), form stable monolayers at the air-water interface and they adopt an organization very different from those found for persubstituted CDs. The differences are attributed to the higher conformational flexibility of these compounds, which allows the organization of the CD units with the cavity perpendicular to the interface.

Preparation and sorption studies of polyester microsphere copolymers containing β-Cyclodextrin

“…TCl-1/SCl-1) were measured in the presence of variable levels of PNP using 1-D and 2-D NMR methods in solution to characterize the nature of the copolymer/PNP complexes [37,38]. As noted above, thermodynamic sorption studies provide evidence for the existence of multiple sorption sites for CD-based copolymer sorbents [10,[15][16][17][18][19]. Fig.…”

“…In some cases, isotherm sorption parameters may provide indirect information about the sorption mechanism. Rossi et al [18] reported an amphiphilic CD with multiple recognition sites; whereas, Mohamed et al [11] reported two types of binding sites (i.e. inclusion and interstitial domains) for urethane-based copolymers.…”

Oleic Acid Based Cyclodextrins for the Development of New Hydrosoluble Amphiphilic Compounds

“…This increase in water-solubility was due to the number of carboxylate functions per graft [one for the first series (Table 2; entries 1, 3, 5, 7, 9 and 11) against two for the second series (Table 2; For each compound, the critical aggregation concentration (CAC) and the surface tension (ST) value obtained at this concentration were determined by the Wilhelmy method. [24] Thus, the possibility of a such behavior was checked for -CD- (OSD-Na-[1]-Me)1.6. The dicarboxylate derivatives have a higher CAC than their ester counterparts.…”

Molecular Assemblies of Porphyrins and Macrocyclic Receptors: Recent Developments in Their Synthesis and Applications

“…In this context, the new millennium has witnessed tremendous development in the generation of some novel porphyrin systems by incorporating into them some suitable foreign host material, called molecular receptors. Molecular receptors are macrocyclic, three-dimensional host molecules with guest inclusion capabilities to ensure strong and precise molecular recognition [ 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. Molecular recognition using synthetic compounds is a process where some molecules (hosts) selectively bind other molecules or ions (guests) to produce a well structurally organized system through intermolecular forces and to mimic the mode of action of a natural enzyme by catalyzing specific reactions at ambient conditions.…”