Dimeric cyclodextrin carriers with high binding affinity to porphyrinoid photosensitizers

The aim of our investigation was to develop carrier systems for an application of inert drugs in photodynamic cancer therapy. beta-Cyclodextrin dimers linked at their primary and secondary faces by spacers of varying lengths were synthesized as carrier systems. The binding constants of the inclusion complexes of these cyclodextrin dimers and porphyrinoid photosensitizers were determined by competitive spectrofluorometry. Particularly the secondary face linked dimers exhibited extremely high binding constants with values of 10(6)-10(7) L/mol. Theoretical studies were carried out on these inclusion complexes to confirm the influence of spacer length and connecting side on complex stability.