Inclusion complexes of γ-cyclodextrin and carboxyl-modified γ-cyclodextrin with C60: synthesis, characterization and controlled release application via microgels

Carboxyl modified gamma-cyclodextrin (CDSA) with a substitution degree of about 9.5 was prepared by the esterification of gamma-cyclodextrin (CD) with succinic anhydride in pyridine at 90 A degrees C. The chemical composition and the structure of CDSA were characterized by FT-IR, MALDI-TOF, X-ray diffraction pattern, potentiometric titration and TGA. Modified and native gamma-cyclodextrin associate with fullerene (C-60) in DMF-toluene mixture resulting 1:1 CDSA:C-60 and CD:C-60 inclusion complexes. Aqueous solutions of native cyclodextrin, carboxyl-modified cyclodextrin and their inclusion complexes with C-60 were used as microgel solvent (or swelling agent) for controlled release application. The release of solutions was induced by shear stress and demonstrated using rheo-optical set-up.