Premium
Thermodynamic Analysis of the Uptake of a Protein in a Spherical Polyelectrolyte Brush
Author(s) -
Walkowiak Jacek,
Lu Yan,
Gradzielski Michael,
Zauscher Stefan,
Ballauff Matthias
Publication year - 2020
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201900421
Subject(s) - polyelectrolyte , isothermal titration calorimetry , counterion , enthalpy , chemistry , adsorption , fourier transform infrared spectroscopy , thermodynamics , polymer chemistry , chemical engineering , materials science , polymer , organic chemistry , ion , physics , engineering
A thermodynamic study of the adsorption of Human Serum Albumin (HSA) onto spherical polyelectrolyte brushes (SPBs) by isothermal titration calorimetry (ITC) is presented. The SPBs are composed of a solid polystyrene core bearing long chains of poly(acrylic acid). ITC measurements done at different temperatures and ionic strengths lead to a full set of thermodynamicbinding constants together with the enthalpies and entropies of binding. The adsorption of HSA onto SPBs is described with a two‐step model. The free energy of binding Δ G b depends only weakly on temperature because of a marked compensation of enthalpy by entropy. Studies of the adsorbed HSA by Fourier transform infrared spectroscopy (FT‐IR) demonstrate no significant disturbance in the secondary structure of the protein. The quantitative analysis demonstrates that counterion release is the major driving force for adsorption in a process where proteins become multivalent counterions of the polyelectrolyte chains upon adsorption. A comparison with the analysis of other sets of data related to the binding of HSA to polyelectrolytes demonstrates that the cancellation of enthalpy and entropy is a general phenomenon that always accompanies the binding of proteins to polyelectrolytes dominated by counterion release.