An example of theoretical approaches in polymer hydrogels: insights into the behavior of pH-responsive Nanofilms

Abstract

Due to their self-regulating behavior, pH-responsive hydrogels are frequently considered in the development of functional biomaterials. A rational approach to designing new biomaterials imposes the need to understate their interaction with protein solutions. On the basis of theoretical work, this chapter describes the adsorption of proteins and peptides to films of cross-linked pH-sensitive polymers. Particular emphasis is placed on the physical chemistry that emerges from the charge regulation properties of hydrogels and proteins. As a result of spatial confinement, the acidic units that compose a polymer network modify their protonation state as well as the composition of the surroundings; the local pH drops inside the hydrogel, increasing protein protonation upon adsorption. Having different amino acid residues that protonate or deprotonate under different conditions supplies proteins with degrees of freedom to modify their net charge and, thus, modulate the electrostatic interactions with a given hydrogel that drive adsorption. Tailoring a polymer network’s chemical composition allows for the separation and localization of specific components from multiprotein solutions using pH.