Injectable chitosan mixtures forming hydrogels

A process for preparing a stable pH-dependent and temperature-dependent chitosan hydrogel composition comprised of at least one acetylated chitosan having a degree of acetylation of from about 30% to about 60%, and at least one deacetylated chitosan having a degree of deacetylation that is about 70% to about 95%, which process comprises:

• d) dissolving said acetylated chitosan and said deacetylated chitosan in an acidic aqueous solution at a temperature between 0° C. to 10° C., to thereby form a composite solution, wherein the ratio of said acetylated chitosan and said deacetylated chitosan in said composite solution is in the range of 1:1 to 4:1;
• e) adjusting the pH of said composite solution to a value of 6.6 to 7.4 at a temperature between 0° C. to 10° C.;
• and
• f) increasing at least one of the temperature of said composite solution to about 37° C. and/or raising the pH to physiological pH.

A kit for producing a chitosan hybrid hydrogel, comprising:

• (i) a container containing a chitosan composition comprising at least one acetylated chitosan having a degree of acetylation in the range of from about 30% to about 60%, and at least one deacetylated chitosan having a degree of deacetylation that is about 70% to about 95%, wherein the ratio of said acetylated chitosan to said deacetylated chitosan in the solution is in the range of 1:1 to 4:1;
• (ii) a container containing a cross-linking agent in an amount sufficient to accelerate gelation of the chitosans;
• and
• (iii) instructions for preparing the chitosan hybrid hydrogel.