1. X-Ray Diffraction Analysis

Supporting information

1. X-ray diffraction analysis

The X-ray diffraction of the nanofibers were acquired by X-ray diffractometer (XRD2000, Shimadzu, Japan) with Cu Kα characteristic radiation (wavelength λ=0.154 nm at 40 kV, 50 mA, and scan speed of 1°/min in the 2θ range of 5-70°).

Fig. S1 shows the XRD pattern of electrospun fibers. It could be seen that, MACS had one peak around 2θ =21.1° (Fig. S1a) and PVA powder had four typical peaks at 2θ = 11.3°, 19.3°, 22.5° and 40.6° (Fig. S1d). However, MACS/PVA nanofibers displayed more obtuse and broad peak around 20°, which indicated introduction of MACS decreased in the crystallinity of MACS/PVA blends, possibly because ordered chain associations of PVA was hindered by hydrogen bonding reaction between MACS and PVA during electrospinning process.

Fig. S1. XRD patterns of MACS, PVA and the nanofibrous membranes with different MACS/PVA weight ratio: (a) MACS; (b) 50/50; (c) 25/75; (d) PVA powder.

2. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy

To confirm the removal of PVA, ATR-FTIR was used to examine the mats after water immersion (Fig. S2). PVA shows typical peaks at 3285, 2911, 1730, 1086, 845 cm-1, attributed to O-H stretching, C-H (CH2) stretching, C=O stretching, C-O stretching and C-C stretching, respectively. The FTIR of MACS investigates the absorption bands at 1157 and 895 cm-1, attributed to its saccharide structure. However after photocrosslinked MACS based mats immersed in water for 48 h at 37 ℃, the peak at 845 cm-1 almost disappeared, which indicated PVA was nearly removed.

Fig. S2. ATR-FTIR spectrum of samples.

3. Mechanical properties

Tensile testing of dumbbell-shaped samples (2.5 mm wide at narrow space,15 mm long and ～0.2 mm thickness) was performed by using Instron Universal Testing Machine(5967, USA) at a 1 mm/min crosshead speed at room temperature. The results showed that the tensile strength and elongation value of photocrosslinked MACS/PVA (50/50) nanofibers were 3.37±0.91 MPa and 4.43±0.70 %,respectively. After soaked in purified water for 48 h at 37 ℃, its tensile strength and elongation value decreased to 2.36±0.11MPa,1.56±0.10 %, respectively. That indicated its mechanical properties decreased after PVA extraction. The presence of PVA improved effectively the mechanical properties of the mats.

4. Liquid-uptake capacity

To determine liquid-uptake capacity, photocrosslinked MACS-based mats were immersed in phosphate buffered saline (PBS) solution (pH=7.4) at 37 ℃ for 48 h. The results showed that the photocrosslinked MACS-based mats had water-uptake of 6.41±0.65 (g/g). The mats could absorb relatively high amount of water, probably due to formation of micro-pores structure resulted from leaking of PVA in the mats in PBS solution.