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Isothermal titration calorimetry study of the polyelectrolyte complexation of xanthan and chitosan samples of different degree of polymerization†
Article first published online: 5 JUL 2011
Copyright © 2011 Wiley Periodicals, Inc.
Volume 97, Issue 1, pages 1–10, January 2012
How to Cite
Maurstad, G., Kitamura, S. and Stokke, B. T. (2012), Isothermal titration calorimetry study of the polyelectrolyte complexation of xanthan and chitosan samples of different degree of polymerization. Biopolymers, 97: 1–10. doi: 10.1002/bip.21691
- Issue published online: 24 OCT 2011
- Article first published online: 5 JUL 2011
- Manuscript Accepted: 31 MAY 2011
- Manuscript Received: 28 FEB 2011
- The Norwegian Research Council. Grant Number: 166794/V30
- isothermal titration calorimetry;
- polyelectrolyte complexation
Mixing oppositely charged polyelectrolytes in aqueous solutions leads to the spontaneous formation of polyelectrolyte complexes. Here, we characterize the interaction between xanthan of two different chain lengths, a tri-glucosamine and a chitosan polymer by isothermal titration calorimetry (ITC). Analysis of the experimental thermodynamic data assuming a single set of identical sites indicated both enthalpic and entropic contributions to the overall interaction in the interaction between xanthan and tri-glucosamine. The relative contribution of entropy compared to enthalpy was found to be largest for the shortest chain length of xanthan. Using a chitosan polymer instead of tri-glucosamine gave rise to two different stages in the interaction process. A model where the first stage of the ITC curve represent an initial polyelectrolyte complexation stage followed by aggregation on further titration of chitosan to the xanthan is suggested. Ultrastructure images by applying atomic force microscopy at some selected extents of titration are consistent with the two-stage interpretation of the thermodynamic data. © 2011 Wiley Periodicals, Inc. Biopolymers 97: 1–10, 2012.