Zwitterionic hydrogels and their biomedical applications: a review

The coexistence of anions and cations in zwitterionic hydrogels results in electrostatic interactions between the polymer chains. This structure endows zwitterionic hydrogels with higher ion sensitivity and promising properties, such as anti-polyelectrolyte and thermosensitive effects. Hydrophilic groups on the molecular backbone give zwitterionic hydrogels good biocompatibility, and they effectively resist the non-specific adsorption of proteins. The abundant functional groups on the molecular skeleton also facilitate the chemical modification of zwitterionic hydrogels. In recent years, these excellent properties have made zwitterionic hydrogels broadly interesting and they have been heavily studied for medical applications. A comprehensive review will help researchers have a deeper understanding of zwitterionic hydrogels and their potential applications. In this review, the types, functional characteristics, and applications in the biomedicine of zwitterionic hydrogels are summarized in detail. In addition, the challenges and opportunities for using zwitterionic hydrogels for biomedical applications are discussed.