Strong Silk Fibers Containing Cellulose Nanofibers Generated by a Bioinspired Microfluidic Chip

As spider silks have extraordinary mechanical properties, the design of high-performance artificial silk fibers has been one of the focuses in the field of biomimetic fibers. Cellulose nanofibers (CNFs) have considerable potential being an effective reinforcing agent in biocompatible composites because of their high aspect ratio, good stiffness of the crystalline regions, and biocompatibility. In this study, regenerated silk fibroin (RSF)/CNF hybrid fibers were dry-spun through a microfluidic chip, which mimicked the shape of spider's major ampullate gland. The results showed that the presence of CNF can substantially enhance the mechanical properties of RSF. In specific, the breaking strength of the RSF/CNF fibers with 0.1 wt % CNF was increased to 486 ± 106 MPa with a maximum value of 686 MPa, significantly higher than that of silk fibers from silkworm. The enhancement could be attributed to higher orientation of crystalline and mesophase contents, higher crystallinity, and hydrogen bonds linked between RSF and CNF. This study outlined a simple and environmentally friendly pathway to generate artificial silks with high-performance properties.