The crosslinking process was carried out according to the
method reported by us [28]. Briefly, in a sealed desiccator containing
20 mL of aqueous glutaraldehyde solution (50%, v/v), the
membranes were placed on a holed ceramic shelf in the desiccator
and were crosslinked in the glutaraldehyde vapor at room temperature
for 4 days. After crosslinking, the samples were immersed in
deionized water for 5 days by changing the water every 6 h. Finally,
the crosslinked nanofibers were dried at 60 ◦C in vacuum for 24 h.