Double-crosslinked PNIPAM-based hydrogel dressings with adjustable adhesion and contractility

Rapid post-wound closure is necessary to avoid wound infection and promote scar-free healing when skin trauma occurs. In this study, new types of hydrogel dressings with adjustable contractility were fabricated based on N-isopropyl acrylamide/sodium alginate/graphene oxide (P/SA/GO). Then, the chitosan (CS) solution was used as a bridging polymer to achieve tissue adhesion to the hydrogel. The results show that the hydrogel based on poly(N-isopropyl acrylamide) (PNIPAM) not only has the ability to self-shrink but also can adjust the rate of shrinkage through near-infrared thermal stimulation. At the same time, high adhesion strength (7.86 +/- 1.22 kPa) between the tissue and the dressing is achieved through the introduction of bridging polymers (CS), and the coating area of the bridging polymer can be adjusted to achieve regional adhesion. The mouse total skin defects experiments have shown that sutures-free wound closure in the early stages of wound healing could be obtained by adjusting the material temperature. Besides, the dressings can promote scar-free wound healing by reducing inflammatory cell infiltration and collagen deposition. These results indicate that double-crosslinked PNIPAM-based hydrogel dressings with adjustable adhesion and contractility proposed in this study provide a candidate material for achieving trackless wound healing.