Investigating the Impact of Network Functionalization on Protein Adsorption to Polymer Nanogels

This study explores the impact of network functionalization and chemical composition on the pH-responsive behavior of polymer nanogels and their adsorption of proteins. Using a thermodynamic theory informed by a molecular model, this work evaluates the interactions of three proteins with varying isoelectric points (insulin, myoglobin, and cytochrome c) and pH-responsive nanogels based on methacrylic acid or allylamine motifs. Three different functionalization strategies are considered, with pH-responsive segments distributed randomly, at the center, or on the surface of the polymer network. Our results show that the spatial distribution of functional units affects both the nanogels' mechanical response to pH changes and the level and localization of adsorbed proteins. The dependence of protein adsorption on the salt concentration is also investigated, with the conclusion that it is best to encapsulate proteins at low salt concentrations and aim for release at high salt concentrations. These results provide valuable information for the design of pH-responsive nanogels as vehicles for protein encapsulation, transport, and administration.