Nanoscale Synergy: Transforming First Formed Film of Bacterial Cellulose into High‐Performance Functional Fibers

Abstract Bacterial cellulose (BC) biosynthesis is a dynamic process where its 3D nanofibrous network evolves with culture time, offering ample opportunities to tailor the network for specific applications. Herein, BC‐derived macrofiber with exceptional mechanical and functional properties is reported. The biosynthesis parameters are set to get the First Formed Film (FFF) at the liquid‐air interface on the second day of culture, which has a homogeneous network structure, unlike the layered structures observed in subsequent films. The FFF ultralong nanofibers are converted into macrofiber through controlled plastic deformation and twisting along the fiber length. The resulting fibers exhibit exceptional mechanical properties, including a tensile strength of (2.5 GPa) and a specific strength of (856.16 MPa g⁻¹cm ^{− 3} ), the highest reported for cellulose‐based fibers. The fibers retain approximately 95% of the stiffness of BC nanofibers, demonstrating excellent nanoscale‐to‐macroscale property transfer. Notably, this high strength is achieved without any chemical modification or cross‐linking. Also, FFF hydrogels are functionalized in situ to fabricate magnetic, antibacterial, and conductive fibers. They demonstrate excellent functionality transfer from hydrogel to fiber‐ positioning them as ideal candidates for surgical sutures and soft robotics applications. This study successfully highlights the synergy between BC biosynthesis and its morphology in designing high‐performance materials.