Encapsulation of doxorubicin in carboxymethyl-0-cyclodextrin in aqueous medium mediated by pH-modulated electrostatics interactions

The complexation of doxorubicin with the carboxymethyl-0-cyclodextrin in aqueous medium at different pH values and temperatures was investigated, emphasizing the influence of electrostatic interactions in this complexation. The stoichiometry, the binding constants and the AH0 and AS0 thermodynamic parameters upon inclusion were obtained. The results were compared to those obtained for the doxoru-bicin complexation with the natural 0CD. For this purpose, UV-Vis, steady-state and time-resolved fluo-rescence spectroscopic techniques were employed, as well as Molecular Mechanics and Molecular Dynamics calculations to determine their preferred structures and the interactions taking place, both when the cyclodextrin was charged and when it was not. Among the spectroscopic techniques men-tioned, the fluorescence lifetime of Dox was used to quantitatively study the thermodynamic parameters, since the fluorescence intensity, which is usually employed, was rather less sensitive to this complexation.(c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).