Organo-soluble chitosan salts and chitosan-derived biomaterials prepared thereof

1. A method for preparing chitosan derivative, comprising:

i) dispersing chitosan in an aqueous solution to form a first mixture;

ii) adding a chitosan salt forming acid to the first mixture;

iii) stirring the first mixture containing the chitosan salt forming acid to form a homogenous solution;

iv) adding a solvent to the homogenous solution to precipitate an organo-soluble chitosan salt, wherein the organo-soluble chitosan salt is selected from the group consisting of chitosan sulfonate, chitosan methanesulfonate, chitosan toluenesulfonate, chitosan camphorsulfonate, chitosan salicylate, chitosan trifluoromethanesulfonate, chitosan ethanesulfonate, chitosan phenylbenzimidazolesulfonate, chitosan 1-propanesulfonate, (1R)-(−)-10-camphorsulfonate, and chitosan camphorquinone-10-sulfonate;

v) recovering the organo-soluble chitosan salt;

vi) dissolving the organo-soluble chitosan salt in formamide to form a second mixture;

vii) adding a chitosan derivative forming compound to the second mixture;

viii) reacting the chitosan derivative forming compound with the organo-soluble chitosan salt to obtain a reaction solution containing the chitosan derivative;

ix) stopping the reaction;

x) adding a second solvent to the reaction solution to precipitate the chitosan derivative; and

xi) recovering the chitosan derivative.

2. The method according to claim 1 , wherein the organo-soluble chitosan salt is chitosan methanesulfonate, or chitosan toluenesulfonate.

3. The method according to claim 1 , wherein the chitosan derivative forming compound is N-carboxy α-amino acid anhydrides (NCA) or cyclic anhydride.

4. The method according to claim 1 , further comprising dialyzing the recovered chitosan derivative and freeze-drying the dialyzed chitosan derivative.

5. The method according to claim 1 , wherein the second solvent is acetone or isopropanol.