*2.2. Spinning Solution*

GA (12% *w*/*v*) solutions were obtained through dissolving 1.2 g GA in 10 mL glacial acetic acid after sufficient stirring overnight. PA66 (12% *w*/*v*) solution was obtained through adding 1.2 g PA66 pellets into 10 mL formic acid with stirring overnight. Blend solutions at a final concentration of 12% ( *w*/*v*) with gelatin/PA66 weight ratios of 1/2, 1/1 and 2/1 were obtained through dissolving gelatin and PA66 in glacial acetic acid and formic acid after stirring overnight. The solution was stirred for 6 h and ultrasonic treated for 30 min before the SBS process.

#### *2.3. Solution Blow Spinning (SBS) Process*

The JNS-SBS-01 SBS apparatus (Janus New-Materials Co., LTD, Nanjing, China) was employed to fabricate the nanofibrous films. Solutions were added into a syringe, and the feed rate of syringe pump was 3 mL/h. The distance between nozzle and reticular collector was 20 cm. An air pressure of 0.06 MPa was used to provide a stable shear force. The SBS process was performed at 30 ◦C with a relative humidity of approximately 50%. Obtained films were GA film, PA66 film and gelatin/PA66 (2:1, 1:1, 1:2) films, respectively.
