title: Interactions between Oppositely Charged Polyelectrolytes by Isothermal Titration Calorimetry: Effect of Ionic Strength and Charge Density.
abstract: In this study, binding of linear poly(l-lysine) to a series of acrylamide and 2-acrylamido-2-methyl-1-propanesulfonate copolymers was examined by isothermal titration calorimetry (ITC). Binding constant and stoichiometry were systematically determined at different ionic strengths and for different polyanion charge densities varying between 15% and 100%. The range of investigated ionic strengths was carefully adjusted according to the polyanion charge densities to get measurable binding constants (i.e., formation binding constant typically comprised between 104and 106M-1) by isothermal titration calorimetry (ITC). The number of released counterions during the polyelectrolyte complex formation was determined from the log-log dependence of the binding constant according to the ionic strength and was compared to the total number of condensed counterions estimated from the Manning theory. Experimental results obtained by ITC are in very good agreement with those previously obtained by frontal analysis continuous capillary electrophoresis (FACCE) and can be used to model and predict the binding parameters at any ionic strength or any polyanion charge density. Thermodynamic parameters of the complexation between the oppositely charged polyelectrolytes confirm that the complex formation was entropically driven together with a favorable (but minor) enthalpic contribution. For the first time, specificities, advantages/disadvantages of ITC, and FACCE techniques for studying polyelectrolyte complexations are compared and discussed, using the same experimental conditions.
authors.affiliation: Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier , Place Eugène Bataillon, CC 1706, 34095 Montpellier Cedex 5, France.
authors.forename: Feriel Meriem
authors.initials: FM
authors.lastname: Lounis
authors.affiliation: Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier , Place Eugène Bataillon, CC 1706, 34095 Montpellier Cedex 5, France.
authors.forename: Joseph
authors.initials: J
authors.lastname: Chamieh
authors.affiliation: Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier , Place Eugène Bataillon, CC 1706, 34095 Montpellier Cedex 5, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Leclercq
authors.affiliation: Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier , Place Eugène Bataillon, CC 1706, 34095 Montpellier Cedex 5, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Gonzalez
authors.affiliation: Institut Charles Gerhardt de Montpellier, UMR 5253 CNRS-UM-ENSCM, Université de Montpellier , CC1502, Place Eugène Bataillon, 34095 Montpellier, France.
authors.forename: Amine
authors.initials: A
authors.lastname: Geneste
authors.affiliation: Institut Charles Gerhardt de Montpellier, UMR 5253 CNRS-UM-ENSCM, Université de Montpellier , CC1502, Place Eugène Bataillon, 34095 Montpellier, France.
authors.forename: Benedicte
authors.initials: B
authors.lastname: Prelot
authors.affiliation: Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS, Université de Montpellier, Ecole Nationale Supérieure de Chimie de Montpellier , Place Eugène Bataillon, CC 1706, 34095 Montpellier Cedex 5, France.
authors.forename: Hervé
authors.identifier: 0000-0002-6876-175X
authors.initials: H
authors.lastname: Cottet