HYDROGEL PRODUCED FROM CHITOSAN DERIVATIVE
Provided is a technique for producing a chitosan-derived hydrogel which can be formed into a desired shape without requiring the use of any additive that is harmful to living bodies and which is useful as a wound-covering material. A chitosan derivative in which an aldonic acid (e.g., gluconic acid) is bound to an amino group in a glucosamine unit of chitosan. An aqueous solution containing the chitosan derivative can be transformed into a hydrogel having a desired shape merely by freezing and thawing. The hydrogel may additionally contain a polyvinyl alcohol to improve various properties of the hydrogel, such as strength.