Fig. 4

Morphology and properties testing of SNs, CNs, and ChNs. Transmission electron microscopy (TEM) observation of resultant a BS and b AS nanofibers that oxidized by 10 mM/g protein NaClO addition, c cellulose nanofibers (CNs), and d chitin nanofibers (ChNs) that achieved by TEMPO-mediated oxidation. The scale bar is 500 nm. e UV-Vis transmittance of approximately 50-μm-thick membranes that cast by BS, AS, cellulose (CN), and chitin (ChN) nanofibers. f Representative stress-strain curves of approximately 50-μm-thick membranes that cast by BS, AS, CN, and ChN nanofibers. g Young’s modulus of membranes that are casting from BS, AS, CN, and ChN nanofibers. Data represent the mean SD (n = 5). h–k The water contact angle of membrane cast by f BS nanofibers was 58.8 ± 1.5°, significantly reduced from that of regenerated BS membrane (71.0 ± 0.3°, the inset image). 55.7 ± 0.5, 40.3 ± 1.1, and 52.5 ± 0.6° of water contact angle was presented in AS, CN, and ChN membrane, respectively