Encapsulation of phenolic acids into cyclodextrins: a global statistical analysis of the effects of pH, temperature and concentrations on binding constants measured by ACE methods

Electrophoresis. 2022 Jun 11. doi: 10.1002/elps.202200075. Online ahead of print.

ABSTRACT

Affinity capillary electrophoresis was used for the simultaneous measurement of the $p{K}_a$ values and of the binding constants relative to the encapsulation of naturally occurring phenolic acids (rosmarinic and caffeic acids) with cyclodextrins. A thorough study as a function of pH and temperature was coupled to a detailed statistical analysis of the resulting experimental data. A step-by-step curve fitting process was sufficient for obtaining individual binding constant for each experimental condition, but the influence of temperature remained unclear. A quantitative and qualitative gain was then obtained by supplementing this initial analysis with a global multi-parameters optimization. This lead to the estimation of both entropy and enthalpy of reaction, and to the full description of the binding reactions as a function of pH and temperature. The encapsulation was shown to be very sensitive to pH and temperature, with optimal complexation occurring at low pH and low temperature, gaining up to a factor 3 by cooling from 36°C to 15°C, and up to a factor 10 by lowering the pH from 7 to 2. This article is protected by copyright. All rights reserved.

PMID:35689604 | DOI:10.1002/elps.202200075