Thermodynamic Analysis of the Uptake of a Protein in a Spherical Polyelectrolyte Brush.

Journal Article (Journal Article)

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 ΔGb 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.

Full Text

Duke Authors

Cited Authors

  • Walkowiak, J; Lu, Y; Gradzielski, M; Zauscher, S; Ballauff, M

Published Date

  • January 2020

Published In

Volume / Issue

  • 41 / 1

Start / End Page

  • e1900421 -

PubMed ID

  • 31697416

Electronic International Standard Serial Number (EISSN)

  • 1521-3927

International Standard Serial Number (ISSN)

  • 1022-1336

Digital Object Identifier (DOI)

  • 10.1002/marc.201900421


  • eng