Biomimetic Grooved Spinneret Enables High‐Performance Regenerated Silk Fibers Surpassing Natural Silkworm Silk

Abstract Natural silk fibers, particularly silkworm and spider silks, demonstrate remarkable strength and toughness, yet face limited applications attributed to their non‐uniform mechanical properties. Regenerated silk fibers (RSFs), uniformly produced by artificial spinning, thus hold potential as alternatives to natural silks. However, the mechanical properties of RSFs are often inferior to natural silks due to the challenge of replicating their hierarchical nanofibril structure. Here, a grooved spinneret, inspired by the structural features of a spider's spinneret, is demonstrated to greatly enhance the shear force in the wet spinning process, which effectively increases the pre‐assembly of regenerated silk proteins and therefore improves both the content and alignment of β ‐sheets within the silk. Consequently, the biomimetic RSFs (BRSFs) exhibit a hierarchical nanofibril structure akin to that of natural silkworm silk, yielding a tensile strength of 558.1 ± 25.2 MPa, even surpassing silkworm silk (439.2 ± 68.9 MPa). Significantly, the toughness of the BRSFs reaches 103.7 ± 20.9 MJ m − 3 , nearly three times that of silkworm silk (37.5 ± 7.1 MJ m − 3 ). This work provides a facile and effective biomimetic approach for producing strong and tough RSFs, with the potential to upcycle silk waste into high‐value products, showing substantial environmental and economic advantages for sustainability.