Bio-inspired tissue adhesive chitosan/pluronic composite hydrogel

Tunicate-mimetic nanofibrous hydrogel adhesive with improved wet adhesion

The main impediment to medical application of biomaterial-based adhesives is their poor wet adhesion strength due to hydration-induced softening and dissolution. To solve this problem, we mimicked the wound healing process found in tunicates, which use a nanofiber structure and pyrogallol group to heal any damage on its tunic under sea water. We fabricated a tunicate-mimetic hydrogel adhesive based on a chitin nanofiber/gallic acid (a pyrogallol acid) composite. The pyrogallol group-mediated cross-linking and the nanofibrous structures improved the dissolution resistance and cohesion strength of the hydrogel compared to the amorphous polymeric hydrogels in wet condition. The tunicate-mimetic adhesives showed higher adhesion strength between fully hydrated skin tissues than did fibrin glue and mussel-mimetic adhesives. The tunicate mimetic hydrogels were produced at low cost from recyclable and abundant raw materials. This tunicate-mimetic adhesive system is an example of how natural materials can be engineered for biomedical applications.

Laser-activated adhesive films for sutureless median nerve anastomosis

A novel chitosan adhesive film that incorporates the dye 'Rose Bengal' (RB) was used in conjunction with a green laser to repair transected rat median nerves in vivo. Histology and electrophysiological recording assessed the impact of the laser-adhesive technique on nerves. One week post-operatively, the sham-control group (laser-adhesive technique applied on un-transected nerves) conserved the average number and size of myelinated fibres in comparison to its contralateral side and electrophysiological recordings demonstrated no significant difference with un-operated nerves. Twelve weeks after the laser-adhesive anastomoses, nerves were in continuity with regenerated axons that crossed the anastomotic site.