The prepared DHC/chitosan hydrogel was immersed in a 2% AgNO3 aqueous solution in the dark for 24 h at room temperature, ensuring the Ag ions could be absorbed into the hydrogels. Then, the hydrogel was immersed in aqueous ammonia (NH3:H2O = 1:5, v/v) to ammoniate the residual Ag ions. Using this procedure, uniform Ag nanoparticles were present in the DHC/chitosan hydrogel. The obtained hydrogel was washed with distilled water several times to remove the ammonia and Ag ions.