Bioinspired polydopamine hydrogels: Strategies and applications

Polydopamine (PDA) is a fascinating bioinspired material for the construction of diverse functional materials. In particular, the growing trend of PDA hydrogels clearly reveals the global significance and the intense interest of scientific research in this field. The abundant functional groups make PDA serve as the important structural units for covalent or/and non-covalent interactions with polymers, and anchoring of transition metal ions for hydrogels formation. With these benefits, PDA not only endows hydrogels with various functions such as adhesion, photothermal effect, ultraviolet protection, antioxidant ability, antibacterial properties, but also has been rapidly incorporated into a wide range of applications across the biomedical, environment, energy, and electronic fields. This review strives to provide a comprehensive overview of the relevant advances in the field of bioinspired PDA hydrogels. We start to introduce the PDA as the structural units in hydrogels and dedicate a lot of space to discuss their design and PDA functions in the hydrogels. Furthermore, these functions would bring about various interesting applications of the hydrogels. Some key issues in this emerging field have been also exhibited into discussion which will inspire our thinking in functional hydrogels design.