Hydrogels formed by polyelectrolyte complexation

This chapter provides a comprehensive look at the process of polyelectrolyte complexation, that is, electrostatic attractions between oppositely charged polymers, and its application for the assembly of biofunctional hydrogels. Polyelectrolyte attraction is a spontaneous phenomenon occurring during many homeostatic events in the human body. It is thus a biomimetic method to fabricate hydrogels. It does not use aggressive solvents and extreme temperatures, which can compromise the constructs’ biocompatibility and the bioactivity of sensitive encapsulated drugs and biologics and therefore can be classified as a green processing approach. Moreover, the polyelectrolyte complexation can be tailored and upscaled to obtain hydrogels of variable dimensions and geometries—from nanocoacervates to macroscopic three-dimensional networks, which turns it versatile and industrially feasible. The properties of the generated hybrid materials can be tuned in terms of molecular composition, stability, and bioactivity, which is pivotal for biomedical and tissue engineering strategies.