Electroactive carbon nanofiber layer for enhancing osteogenic differentiation in vitro

Non-woven nanofiber mats, with high permeability, nutrient diffusivity, and mechanical robustness, are widely used as scaffolds for tissue engineering. Carbon nanofibers (CNFs) are often incorporated into biomaterials to enhance electroactivity and mechanical strength, yet their direct use as scaffolds remains underexplored. Here, we report the fabrication of CNF-coated polycaprolactone (PCL) nanofiber mats (CNF@PCL) via drop-casting of pyrolytically stripped CNFs. Morphological analysis confirmed uniform CNF deposition, producing a nanofibrous surface architecture. CNF@PCL exhibited dramatically enhanced electrical conductivity (2.921 (± 0.19) × 10⁻⁴ Ω⁻¹·cm⁻¹), four orders of magnitude higher than pristine PCL (3.253 (± 0.14) × 10⁻⁸ Ω⁻¹·cm⁻¹). MC3T3-E1 preosteoblasts proliferated comparably on both scaffolds, whereas CNF@PCL significantly promoted early osteogenic differentiation, as indicated by elevated ALP activity at day 14 and robust mineralized calcium deposition. These results demonstrate that electroactive CNF matrices can functionally mimic electrospun nanofibers, offering a promising platform for bone tissue regeneration and motivating further in vivo validation. Graphical abstract