Ultratough Fibroin Film Enables Composite Membranes with Superior Osteogenesis for Guided Bone Regeneration

Fibroin films hold promise as high-performance biomaterials for demanding biomedical applications, such as load-bearing tissue interfaces and implantable membranes. However, engineering protein-based films with both high toughness and strength remains a significant challenge. Here, we develop an ultratough fibroin film with an exceptional toughness of 104 MJ/m³ while maintaining a tensile strength of 232 MPa. This is achieved through near-complete cross-linking of high molecular weight (MW) regenerated fibroins, followed by controlled strengthening-plasticization treatment. The ultratough film closely mimics the unique nanostructure profile of spider dragline silk, featuring small β-nanocrystallites embedded within a matrix rich in noncrystalline β-sheets. We further fabricate a bilayer membrane by integrating nano/microscale silk fibers onto the ultratough film. The resulting composite exhibits substantially enhanced guided bone regeneration, surpassing clinical standard performance. This fibroin-based film and membrane system combine scalable fabrication, mechanical resilience, and biological functionality, offering a practical solution for tough, bioresorbable medical implants.