The fiber morphology was observed under scanning electronic microscopy (SEM) using a JEOL JSM-5800LV
machine with an acceleration voltage of 15 kV.
Before SEM observation, all of the samples cut from the electrospun fiber mats of 2.5–15% w/v mass concentrations were sputter coated with gold under a JEOL JFC-1200 fine coater for 60 s.
Typically representative SEM photographs of all the fiber mats with different gelatin concentrations are shown in Figs. 2–7. Based on these SEM photos, the fiber diameters of the different concentration nanofibrous mats were analyzed using an image visualization software ImageJ developed by Upper Austria University of Applied Sciences