Large Changes in Protonation of Weak Polyelectrolyte Brushes with Salt ConcentrationImplications for Protein Immobilization
online resourceposted on 09.07.2020, 14:07 by Gustav Ferrand-Drake del Castillo, Rebekah L. N. Hailes, Andreas Dahlin
We report for the first time that the protonation behavior of weak polyelectrolyte brushes depends very strongly on ionic strength. The pKa changes by one pH step per order of magnitude in salt concentration. For low salt concentrations (∼1 mM), a very high pH is required to deprotonate a polyacidic brush and a very low pH is required to protonate a polybasic brush. This has major consequences for interactions with other macromolecules, as the brushes are actually almost fully neutral when believed to be charged. We propose that many previous studies on electrostatic interactions between polyelectrolytes and proteins have, in fact, looked at other types of intermolecular forces, in particular, hydrophobic interactions and hydrogen bonds.