Well‐Aligned Hierarchical Design of High Strength Anisotropic Chitosan Fibers by Electrostatic Regulation for Absorbable Sutures

Chitosan fibers prepared by conventional wet-spinning methods result in significantly compromised wet-state mechanical strength, attributed to hydrogen bonding that hinders molecular chain alignment. To address this critical challenge, this study develops an electrostatically regulated sacrificial micelle-assisted alignment strategy to fabricate high-performance anisotropic chitosan fibers for absorbable sutures. Utilizing sodium dodecyl sulfate (SDS) micelles, electrostatic regulation disrupts intermolecular hydrogen bonds in chitosan, enables uniaxial chain alignment during drawing, and reconstructs a dense hydrogen-bonded network upon micelle removal with NaOH. The resulting pure chitosan fibers (Chit⁰) exhibit exceptional mechanical properties, achieving a dry tensile strength of 293.6 ± 31.0 MPa and retaining 105.0 ± 17.2 MPa under wet conditions-significantly surpassing conventional wet-spun chitosan fibers. Microscopically, the fibers exhibit aligned aggregates with reduced d-spacings, effectively enhancing mechanical properties. The fibers demonstrate outstanding cytocompatibility, negligible in vivo inflammatory response, and controllable degradation kinetics (44% strength retention after 2-week implantation). Animal experiments confirm accelerated wound healing with minimal scarring, outperforming commercial poly(glycolic acid) sutures in biocompatibility. This strategy offers a versatile paradigm for engineering anisotropic biopolymer fibers with balanced wet-strength and biofunctionality.