Investigation on a host-guest inclusion system by β-cyclodextrin derivative and its analytical application

The host-guest inclusion system of ethyl substituted β-cyclodextrin (DE-β-CD) with mangiferin (MA) was investigated by fluorescence spectra in solution. The results showed that the MA was encapsulated in the DE-β-CD's cavity to form a 2:1 stoichiometry host-guest inclusion complex (DE-β-CD/MA) and the inclusion constant (K = 3.04 × 10⁶ L²/mol²) was confirmed by the typical double reciprocal plots. Furthermore, several experimental conditions were optimized in order to obtain the maximum fluorescence signal. In addition, the thermodynamic parameters, Gibbs free energy (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) of DE-β-CD/MA were obtained by the Van't Hoff equation. A spectrofluorimetric method for the determination of MA in solution in the presence of DE-β-CD was developed based on the remarkable enhancement of the fluorescence intensity of MA. The linear range was 2.00 × 10^-8-7.00 × 10^-6 mol/L and the detection limit was 4.05 × 10^-9 mol/L. The proposed method was successfully applied to the analysis of MA in serum with the satisfactory result.