Supercritical solution impregnation (SSI) process was applied to prepare asymmetric chitosan films (ACFs) loaded with silver sulfadiazine (AgSD) suitable for wound dressing.ACFs with different dense layers (65 m and 125 m) and porous layers were first prepared using solvent casting and lyophilization method respectively

and then AgSD was loaded into ACFs using SSI process.The effects of impregnation pressure (from 8 MPa to 30 MPa) and temperature (40

50 and 60 ℃) on drug loading capacity (DLC) were investigated in detail

and the properties of AgSD-ACF were characterized such as morphology

water uptake (WU)

water vapor transmission rate (WVTR)

in vitro release

antibacterial and animal tests.The results showed that DLC of the AgSD-ACF increased with the elevation of the pressure and decreased when the pressure increased further; while the temperature affected the DLC in a complex manner

and the maximum DLC was achieved to be 5.0 mg/g at 20 MPa and 50 ℃.The in vitro release study indicated that the AgSD-ACF could prolong the release of AgSD to beyond 10 h under a sustained manner.The water uptake and water vapor transmission rate of AgSD-ACFs could be well adjusted by changing the thickness of the dense layer.AgSD-ACFs had a remarkable antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. The result of animal test showed that AgSD-ACFs could promote the healing of the wounds in SD rats.The supercritical solution impregnation method makes it possible to fabricate drug loaded polymer matrix without using organic solvents and high temperature

which provide a promising way to prepare drug loaded films for potential applications in wound dressing.