Fabrication of high-strength collagen fibers via a novel integrated liquid crystal and microfluidic spinning

Collagen is an ideal raw material for biological fibers, yet achieving long-range structural order and the resultant high-strength fibers without toxic crosslinkers remains a major challenge. This work integrates ultrasonic fragmentation with dialysis concentration to induce a stable lyotropic liquid crystalline (LC) collagen dope at a concentration as low as 3.3%, which is significantly lower than previously reported. Ultrasonic treatment reduced collagen fragment length to 10–30 nm, lowering steric hindrance and enhancing molecular mobility, thereby promoting nematic LC formation. Rheological analysis revealed that at 3.7%, the spinning dope exhibited a characteristic viscosity plateau in the low shear rate range of 1–5 s −1 , indicating shear-induced alignment of nematic LC domains, which defines the optimal spinning window. Using 4.0% LC dope and an optimized ethanol flow rate of 0.30 mL/min in microfluidic spinning process, the resultant collagen fibers achieved a high tensile strength of 2.21 cN/dtex and a thermal denaturation temperature of 120.8 °C. Increasing the spinning dope concentration progressively reduced lateral molecular packing distance, transformed the fiber surface from grooved to smooth, and enhanced thermal stability. This study establishes a rational, crosslinker-free strategy to fabricate high-performance pure collagen fibers with superior mechanical and thermal properties, providing critical theoretical and technical support for their application in absorbable surgical sutures and regenerative medicine. Download: Download high-res image (219KB) Download: Download full-size image