Biosynthetic protein and nanocellulose composite fibers with extraordinary mechanical performance

Typical cellulose fibers exhibit a high mechanical strength but very low toughness, which severely limits their high-tech applications. It is thus becoming urgently important to develop new strategies to simultaneously improve their strength and toughness. In this regard, a new type of biomacromolecular composite fibers is fabricated by wet-spinning a solution of biosynthetic protein and nanocellulose. In stark contrast to pristine cellulose fibers, significantly improved mechanical performance, e.g., 551.2 MPa maximum breaking strength, 40.6 MJ m⁻³ toughness, and 12.5% extensibility were realized in a versatile way. Notably, robust fiber meshes with good impact resistance ability were developed. They can withstand a gravity potential energy of 0.020 J, which is 1.4-fold higher than their pristine nanocellulose counterparts. Moreover, their excellent biocompatibility and superior mechanical properties allow the composite biological fibers for efficient surgical suturing. This work offers a new strategy to fabricate high-performance biological fibers for high-tech applications.