Chitosan film was fabricated by freeze drying technique with
a ternary solvent system. Briefly, 1% (v/v) of acidic water solution
was prepared with a mixture of 0.9 ml of acetic acid and 89.1 ml of
water, then 10 ml of dioxane and DMSO mixed solution with different
volume ratios were added into acetic acid solution. Finally,
1.25 g of chitosan was dissolved in the as-prepared ternary solvent
system and the solution was stayed overnight with magnetic stirring.
Samples were divided into glass vials and frozen at
−18 ◦C for
at least 6 h. Chitosan films were obtained by freeze drying gelled
samples under 50 Pa and
−50 ◦C in a freeze dryer (FD-1C-50) and
stored in a desiccator until test