A fluorescence spectroscopy approach for fast determination of β-cyclodextrin-guest binding constants

Cyclodextrins are capable of forming host-guest inclusion complexes with a variety of guest molecules. However, binding constant measurements of various host-guest inclusions require complex equipment like NMR. Current methods may make binding constant measurement extremely difficult or even impossible for some guest molecules with specific or complicated structures. In this paper, we discovered a new method to determine the binding constants of complexes between β-Cyclodextrin and guest molecules using an inducible fluorophore, Alizarin Red S. The β-Cyclodextrin binding constants of various guest molecules including amino acids, anticancer drugs, antibiotics, and peptides were calculated according to the competition method. This novel florescence spectroscopic technique is reliable and reproducible, and represents an easy and accurate way for β-Cyclodextrin-guest binding constants measurement.