Manufacturing Silk Fibroin Hollow Nanoyarns as Fundamental Units for Advanced Medical Textiles.

Nature-inspired designs aim to replicate the hierarchical structure observed in native tissues. Fibers serve as fundamental modular units, enabling the fabrication of complex architectures for the engineering of medical textiles and tissue equivalents. However, synthetic yarns lack inherent biological cues to support tissue integration, leading to a growing interest in yarns derived from natural materials. Here, we describe for the first time the fabrication of hollow nanoyarns from pure silk fibroin (SF) using an advanced funnel electrospinning process. This yielded long SF nanoyarns, spanning several meters, with adequate tensile strength (1.47 MPa) and stretching performance (166.4%). Moreover, the yarns were compatible with autoclaving, permitting effective sterilization and long-term storage, making them suitable for biomedical applications. Indirect cytocompatibility assessment of the scaffolds in accordance with ISO 10993-5 guidelines revealed high metabolic activity for human umbilical vein endothelial cells and human smooth muscle cells, confirming that the scaffolds were nontoxic. Analysis of TNF-α secretion by macrophages showed that the SF scaffolds exhibited low immunogenicity. Furthermore, the structural resilience and flexibility of the yarns supported bottom-up assembly into textile constructs by weaving. This study not only shows for the first time the feasibility of producing SF nanoyarns but also highlights their compelling potential in the field of sustainable and medical textiles.