Biofunctionalization of plasma-treated polylactic acid microfibers with silk fibroin for peripheral nerve repair

Peripheral nerve injuries (PNIs) cause severe functional impairments and represent a significant clinical and socio-economic challenge. Autologous nerve grafts remain the gold standard practice, but their use has many drawbacks. Nerve guide conduits (NGCs) are a promising alternative. However, their regenerative performance is still inferior to autografts. Filling NGCs with internal guidance structures such as microfibers, may enhance their ability to support nerve repair. Polylactic acid (PLA) microfibers are a widely used biomaterial for scaffold fabrication due to its biocompatibility and processability, yet its bioinert surface lacks specific interaction sites for neural cells, necessitating biofunctionalization. In this study, PLA microfibers were treated with oxygen plasma to enable the stable incorporation of silk fibroin (SF), a bioactive protein known to promote cellular adhesion and neurite outgrowth. In vitro assays with Schwann cells and dorsal root ganglia demonstrated that while plasma-induced surface roughness improved cellular attachment and axonal growth compared to untreated PLA, the incorporation of SF had a markedly greater effect. These findings position SF-PLA microfibers as promising internal guidance structures for next-generation NGCs in peripheral nerve repair.