Novel amino-cyclodextrin cross-linked oligomer as efficient carrier for anionic drugs: a spectroscopic and nanocalorimetric investigation

A large variety of cross-linked cyclodextrin polymers exhibiting interesting properties towards various guests have been characterized. Some polymeric nanoparticles based on cyclodextrins have been tested in clinical trials as nanotherapeutics for cancer. Recently, oligomers have been also synthesized and the advantages of their low molecular weight have been highlighted. In this context, we have synthesized a new cross-linked amino-beta-cyclodextrin oligomer of 3A-amino-3A-deoxy-2A(S),3A(R)-beta-cyclodextrin of about 11 kDa. The inclusion capability of the oligomer for the model drug diclofenac was investigated in neutral aqueous solution by spectroscopy and nano-isothermal titration calorimetry and compared to both beta-cyclodextrin and a soluble cross-linked beta-cyclodextrin polymer. The log K values and the thermodynamic parameters for the interaction of the hosts with diclofenac have been determined. Results suggested that the presence of the polymer backbone does not perturb the molecular recognition ability of the cyclodextrin cavities and the amino groups play a key role in the inclusion process of diclofenac.