Preparation of Antibacterial Biobased Fibers by Triaxial Microfluidic Spinning Technology Using Ionic Liquids as the Solvents

Bacterial infections have become a serious threat to public health. The utilization of antibacterial textiles offers an effective way to combat bacterial infections at the source, instead of relying solely on antibiotic consumption. Herein, efficient and durable antibacterial fibers based on quercetin and cellulose were prepared by a triaxial microfluidic spinning technology using ionic liquids (ILs) as the solvents. It was indicated that the structure and properties of the antibacterial fibers were affected by the type of IL and the flow rates during the triaxial microfluidic spinning process. Quercetin regenerated from [Emim]Ac underwent structural transformation and obtained an increased water solubility, while quercetin regenerated from [Emim]DEP remained unchanged, which was proven by FI-IR, XRD, and UV analyses. Furthermore, antibacterial fibers regenerated from [Emim]Ac exhibited the highest antibacterial activity of 96.9% against S. aureus, achieved by reducing the inner-to-outer flow rate ratio to 0 and concentrating quercetin at the center of fibers. On the other hand, when [Emim]DEP was used as the solvent, balancing the inner-to-outer flow rate ratio to concentrate quercetin in the middle layer of the fiber was optimal for achieving the best antibacterial activity of 93.3% because it promised both the higher encapsulation efficiency and release rate. Computational fluid dynamics (CFD) mathematically predicted the solvent exchange process during triaxial spinning, explaining the influence of IL types and flow rates on quercetin distribution and encapsulation efficiency. It was indicated that optimizing the distribution of antibacterial agents within the fibers can fully unleash its antibacterial potential while preserving the mechanical properties of the fiber. Therefore, the proposed simple triaxial spinning strategy provides valuable insights into the design of biomedical materials.