Catechol Hydrogel as Wet Tissue Adhesive

Wet adhesion plays an important role in the gestation and development of life. The research shows that hydrogel is a kind of intelligent material with both solid and liquid properties. They have been widely used in such areas as wound closure and repair, cell engineering and tissue engineering, owing to their noteworthy versatility and bio-compatibility. However, the physiological environment is usually wet, and the hydration layer on wet tissue surface prevents hydrogel from forming interfacial adhesion bonds with tissue surface. Faced with this challenge, inspired by the fact that the catechol group of DOPA is critical group for the underwater adhesion of mussels, the structure and functional unit design of catechol hydrogel have attracted wide attention. This review introduces the structure and wet adhesion mechanism of mussel foot proteins (Mfps), and the main types of catechol derivatives are classified into natural Mfps or Mfps synthesized by genetic engineering, catechol small molecular compounds, natural polymers modified by catechol groups and synthesized functional polymers containing catechol groups. Nextly, the research progress of catechol hydrogel as wet tissue adhesive in the past decade is summarized, such as tissue wound repair materials, biological coating materials, targeted drug delivery materials and bioelectronic equipment materials. Finally, the opportunities and challenges of catechol hydrogel are prospected.