A Mean-Field Approach to Study Charge Regulation on the Peptides Adsorption onto Charged Surfaces

Some studies show that charge regulation affects the adsorption process of peptides onto charged lipid membranes. Inspired by this, we apply a theoretical model in which pH-sensitive peptides interact with a charged planar surface, in which the mean electrostatic potential can affect the protonation probability of the titratable aminoacids residues. The mean field model is based on an extension of the Poisson Boltzmann equation that includes the effects of the collective charge regulation and the dimensions of species in solution through the Bikerman model. The system is described using a variational approach, in which the minimization of a free energy functional result in a Modified Poisson Boltzmann equation solved by finite differences numerical method. The peptide concentration and mean charge are obtained as a function of the distance from the surface. This enables us to provide a zeta potential estimation that can be compared directly with experimental results.