Fig. 2
Representative SEM observation of resultant silk fibers in each process. a Disassembled BS fibers after formic acid pretreatment, b oxidized BS fibers, and c the BS nanofibers with a diameter of 105 ± 27 nm. d Disassembled AS fibers after formic acid pretreatment, e oxidized AS fibers, and f the AS nanofibers with a diameter of 112 ± 33 nm. The contour length of BS and AS nanofibers is more than 1 μm