Design to multiscale engineering: continuous fibers fabrication from natural proteins and polysaccharides: A review

The adaptability in device construction, customizable mechanical properties, and biocompatibility of fibers have led to their extensive utilization in flexible sensors, biomedical devices, and environmental management. Biopolymer-derived fibers are promising materials for next-generation applications due to their abundant availability and exceptional biocompatibility. This review provides a comprehensive overview of biopolymer-derived fibers, aiming to summarize the advancements in fibers productions and applications. The focus is on elucidating the properties of spinning dope and the development of spinning techniques, with particular emphasis on the molecular structure and aggregate arrangement of natural polysaccharide polymers (cellulose, chitin) and natural protein polymers (silk fibroin, collagen). By conducting a comparative analysis of the rheological properties of biopolymer spinning dope, this review aims to elucidate the influence of viscosity and shear stress, etc., on both the fiber process and final fiber morphology. By elucidating the multiscale structure-property relationships from nanoscale hierarchical architectures and molecular assembly structures to macroscopic phase transitions (e.g., sol-gel transition, fiber solidification during solvent evaporation), this review also analyzes and proposes effective strategies for enhancing the mechanical properties of the resultant fibers. Moreover, current applications of these biopolymer-based fibers in various fields are provided. Finally, the opportunities and challenges associated with potential industrial-scale production are comprehensively discussed. This review article provides a forward-looking perspective on future research directions by proposing strategies to enhance the application potential of biopolymer-based fibers in high value-added fields through precise regulation of molecular structure and aggregate state, as well as optimization of and process parameters.