New amphiphilic derivatives of cyclodextrins for the purpose of insertion in biological membranes:: The "cup and ball" molecules

Structural investigations of beta-cyclodextrin derivatives obtained in solution by nucleophilic substitution with diamino alkanes N-protected by the bulky Boc dagger group are presented. These new compounds are models for amphiphilic transporters to be included in organized phases such as liposomes. It is shown here that the terminal bulky hydrophobic Boc group precludes inclusion of the chain in the cavity of the cyclodextrin. Two-dimensional NMR experiments are used in conjunction with competition with external guests to assess the general concept of "Cup and Ball" molecules. The incorporation of these new amphiphilic cyclodextrins into preorganized molecular systems such as phospholipidic vesicles is investigated using H-1, C-13 and P-31 NMR. The validation and quantification of this incorporation are further evidenced by differential scanning calorimetry and immunological methods using specific antibodies.