β-Cyclodextrin and folic acid host-guest interaction binding parameters determined by Taylor dispersion analysis and affinity capillary electrophoresis.

The thermodynamic properties of molecular recognition in host-guest inclusion complexes can be studied by Taylor dispersion analysis (TDA). Host-guest inclusion complexes have modest size, and it is possible to get convergent results fast, achieving greater certainty for the obtained thermodynamic properties. Cyclodextrins (CDs) and their derivatives can be used as drug carriers that can boost stability, solubility, and bioavailability of physiologically active substances. A simple and effective approach for assessing the binding properties of CD complexes that are critical in the early stages of drug and formulation development is needed to fully understand the process of CD and guest molecules' complex formation. In this work, TDA was successfully used to rapidly determine interaction parameters, including binding constant and stoichiometry, between β-CD and folic acid (FA) along with the diffusivities of the free FA and its complex with β-CD. Additionally, the FA diffusion coefficient obtained by TDA was compared to the results previously obtained by nuclear magnetic resonance. Affinity capillary electrophoresis (ACE) was also used to compare the binding constants obtained by different methods. The results showed that the binding constants obtained by ACE were somewhat lower than those obtained by the two TDA procedures.