Improving ITC studies of cyclodextrin inclusion compounds by global analysis of conventional and non-conventional experiments

Abstract

SummaryThe study of 1:1 cyclodextrin inclusion compounds by isothermal titration calorimetry was explored in a theoretical and experimental point of view to compare the efficiency of conventional and non-conventional experiments. All direct and competitive protocols were described and evaluated in terms of accuracy on both binding constant and inclusion enthalpy. Significant improvement in the calorimetric characterization may be obtained by means of the global analysis of non-conventional experiments coupled to the standard titration protocol. While the titration-release approach proved to be the most accurate strategy for classical complexations, the valuable contribution of other non-conventional experiments was demonstrated for issues concerning weak stability, enthalpy, or solubility.

Evaluation of three neutral capillary coatings for the determination of analyte-cyclodextrin binding constants by affinity capillary electrophoresis. Application to N , N ⿲-disubstituted piperazine derivatives.

“…We have determined the binding constants using fused-silica capillary for the complexes ibuprofen-␤-CD (K = 9 332 M −1 ) and ibuprofen-HP-␤-CD (K = 5 178 M −1 ). Our results are in total agreement with the published results obtained by ITC (K = 9502 M −1 and K = 5146 M −1 , respectively) [41]. So, we have chosen to evaluate the possible adsorption of CDs by comparison of the binding constants determined for various analyte-CD complexes with the uncoated and coated capillaries (the reference being the result obtained with the uncoated capillary).The complexes must be carefully chosen, after will be assured that the analytes do not adsorb on the capillary wall.Several complexes were studied in order to generalize the study of the CD adsorption.…”

Layer‐by‐layer coating of textile with two oppositely charged cyclodextrin polyelectrolytes for extended drug delivery

“…Binding constants ( K in M −1 ), binding stoichiometry ( n ) and inclusion enthalpies (Δ H ° in kJ mol −1 ) were deduced from binding isotherms (assuming a 1:1 stoichiometry), by nonlinear analyses of complexation heats as a function of total concentrations. Treatment were realized by using a dedicated homemade program . Noncompetitive experiments were employed to study the inclusion compounds with one host and one guest.…”

“…Treatment were realized by using a dedicated homemade program. 61 Noncompetitive experiments were employed to study the inclusion compounds with one host and one guest. The first protocol (titration of CD (5 mM in syringe) on TBBA (0.5 mM in cell)) was used for bCD, polyEP-CD, polyEPG-CD-1, and polyEPG-CD-10, the second protocol (titration of TBBA (5 mM in syringe) on polyCTR-CD (0.5 mM in cell)) was employed for polyCTR-CD because of higher heats of dilution for this polymer.…”

Encapsulation of Chaotropic closo‐Decahydrodecaborate Clusters Within Cyclodextrins: Synthesis, Solution Studies, and DFT Calculations

“…As NMR experiments showed that the studied systems were characterized by weak interactions between the host and the guest, it became obvious that dedicated protocols should be employed, in order to replace the classical titration experiment, which is not suitable for weak affinities. In particular, it has been demonstrated that release, annihilated release and reverse titration experiments could significantly increase the accuracy of ITC characterization in the case of weak complexes . As a result, these three protocols were applied for both β‐CD and γ‐CD inclusion compounds.…”

“…After a preliminary study based on classical titrations, theoretical investigations were carried out in order to optimize the accuracy resulting from distinct experiments, for the different host‐guest systems. A combination of dedicated protocols was thus designed, associating release, annihilated release, reverse titration and competitive release . All experimental concentrations are summarized in Table .…”