Robust collagen filaments with aligned mesoscale aggregates as building blocks for surgical sutures

Collagen aggregates (CAs) with hierarchical mesoscale organization endow biological tissues with exceptional mechanical properties through their multiscale structural organization. Compared with artificial assemblies obtained from regenerated collagen solution, natural CAs offer enhanced biocompatibility and superior performance in tissue repair. In this study, CAs were utilized as structural building blocks to fabricate continuous collagen filaments (CFs) via an extrusion-based spinning approach. The obtained CFs and their assembled yarns, featuring aligned microstructure formed during extrusion, exhibited significantly improved strength and toughness (tensile strength of 412.6 ± 20.1 MPa, elongation at break of 24.6 ± 3.2 %, Young's modulus of 5.070 ± 0.096 GPa, toughness of 62.9 ± 9.2 MJ·m^-3), surpassing conventional collagen-derived filaments and outperforming most biomass-derived filaments. When applied as surgical sutures, the CFs and their assembled yarns demonstrated minimal tissue damage and higher cytocompatibility than commercial sutures. In both murine subcutaneous implantation models and Sprague-Dawley rat wound healing models, the CFs yarns showed controlled biodegradation, promoted tissue regeneration, and accelerated wound closure. These findings advance the design and fabrication of collagen-based biomaterials with naturally evolved architectures for regenerative medicine.