Solution Blow Spinning and Molecular Ordering of Regenerated Silk Fibroin: Linking Degumming, Rheology, and CNC-Induced β-Sheet Formation

Silk fibroin nanofibers are promising biomaterials for tissue engineering, wound healing, and controlled release, owing to their biocompatibility, biodegradability, and mechanical robustness. This study demonstrates a scalable route for producing regenerated silk fibroin (RSF) nanofibers using solution blow spinning (SBS) and establishes how degumming, doping rheology, and cellulose nanocrystal (CNC) reinforcement collectively govern fiber formation and performance. Three degumming methods, boiling water, autoclave treatment, and sodium carbonate, were systematically compared, revealing significant differences in sericin removal efficiency, viscosity-average molecular weight, and secondary structure. RSF was regenerated through lithium bromide dissolution and ethanol-induced phase separation, eliminating the need for dialysis. A 10 wt % RSF dope provided optimal rheological behavior for SBS, while CNC incorporation (0.5–1.5 wt %) increased viscosity moderately and promoted finer jet stretching. Furthermore, CNC addition enhanced molecular ordering, increased the β-sheet content and crystallinity, reduced the fiber diameter, and significantly improved tensile properties. Uniform, bead-free nanofiber mats were obtained, and characterization by scanning electron microscopy, Fourier transform infrared spectroscopy, wide angle X-ray diffraction (WAXD), thermogravimetric analysis, and mechanical testing confirmed CNC-induced structural refinement and reinforcement. Overall, this work establishes SBS as a practical platform for producing structurally tunable RSF/CNC nanofibers and identifies key processing–structure–property relationships relevant to biomedical applications, including future integration of bioactive agents for sustained release.