▎ 摘　　要

NOVELTY - Composite hydrogel comprises chitosan and nitrogen-doped graphene chitosan and nitrogen-doped graphene which are chemically crosslinked. The molecular weight of chitosan is 8000-12000 daltons and the mass ratio of nitrogen-doped graphene to chitosan is 0.1:1-5:1. USE - The hydrogel is useful for preparing chronic wound repair product (claimed). ADVANTAGE - The hydrogel has good biocompatibility and high mechanical strength, is non-irritating to tissues and simple, improves local micro-environment of the wound, accelerates wound healing and prevents infection. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the hydrogel comprising (i) dissolving chitosan in water, sequentially adding crosslinking agent and nitrogen-doped graphene and stirring under sealing condition, and (ii) dialyzing the solution obtained in step (i) and pouring the dialyzed solution into a mold and irradiating under sealed conditions.