BSA Induced Domain Transformations in Polyelectrolyte Complex Hydrogels*

Hydrogels are water-laden three-dimensional (3D) networks which have a myriad of applications. Polyelectrolyte complex (PEC) hydrogels are physically-crosslinked hydrogels that expand the utility of hydrogel materials owing to their electrostatically self-assembled networks formed when two oppositely-charged ABA polyelectrolytes microphase separate (limited by their neutral middle blocks). The resulting polymer dense domains serve as connecting nodes in a 3D polymer network. PEC hydrogels have unique attributes including tunable shear properties, stimuli-responsiveness, and macromolecular entrapment, providing a distinct advantage over covalent hydrogels. The structural evolution of PEC hydrogels when varying polymer concentration, polymer length, and salt has been studied, but their behavior in the presence of proteins has not. In this presentation, we use PEC self-assembly as a tool to guide the model protein, BSA, into PEC hydrogel domains and use small-angle X-ray scattering to elucidate morphological transformations, while unveiling the limits of protein encapsulation. This work demonstrates the ability of PEC hydrogels to act as depots for therapeutics and provides a framework for future development of protein-containing PEC hydrogels for biomedical applications.