Combining electrospinning with hot drawing process to fabricate high performance poly (L-lactic acid) nanofiber yarns for advanced nanostructured bio-textiles

Fiber constructed yarns are the elementary building blocks for the generation of implantable biotextiles, and there are always needs for designing and developing new types of yarns to improve the properties of biotextile implants. In the present study, we aim to develop novel nanofiber yarns by combining nanostructure that more closely mimic the extracellular matrix (ECM) fibrils of native tissues with biodegradability, strong mechanical properties and great textile processibility. A novel electrospinning system which integrates yarn formation with hot drawing process was developed to fabricate poly(L-lactic acid) (PLLA) nanofiber yarns (NYs). Compared to the PLLA NYs without hot drawing, the thermally drawn PLLA NYs presented superbly-orientated fibrous structure and notably enhanced crystallinity. Importantly, they possessed admirable mechanical performances, which matched and even exceeded the commercial PLLA microfiber yarns (MYs). The thermally drawn PLLA NYs were also demonstrated to notably promote the adhesion, alignment, proliferation, and tenogenic differentiation of human adipose derived mesenchymal stem cells (hADMSCs) compared to the PLLA NYs without hot drawing. The thermally drawn PLLA NYs were further processed into various nanofibrous tissue scaffolds with defined structures and adjustable mechanical and biological properties using textile braiding and weaving technologies, demonstrating the feasibility and versatility of thermally drawn PLLA NYs for textile-forming utilization. The hADMSCs cultured on PLLA NY-based textiles presented enhanced attachment and proliferation capacities than those cultured on PLLA MY-based textiles. This work presents a facile technique to manufacture high performance PLLA NYs, which opens up opportunities to generate advanced nanostructured biotextiles for surgical implant applications.