Abstract
Electrospun nanofibrous scaffolds which can mimic the architecture of the natural extracellular matrix (ECM) are potential candidates for peripheral nerve repair application. Multi-walled carbon nanotubes (MWCNTs) are used in peripheral nerve repair due to their ability to promote neurite extension and support neural network formation. In this study, surface-modified nanofibrous scaffolds composed of poly(lactic-co-glycolic acid) (PLGA) and various ratios of carboxyl-modified MWCNTs (MWCNTs-COOH) (PC0, PC2, PC4 and PC8) were fabricated by electrospinning. The effects of MWCNTs-COOH on the fibers' morphology, diameter distribution, mechanical properties and surface hydrophilicity were characterized by Scanning Electron Microscopy (SEM), ImageJ software, tensile testing and water contact angle. Furthermore, air plasma treatment was applied to improve the surface hydrophilicity of the scaffolds, and the optimal treatment condition was determined in terms of surface morphology, water contact angle and PC12 cell adhesion. Plasma treated nanofibers (p-PC0, p-PC2, p-PC4 and p-PC8) under optimal treatment conditions were used for further study. PC12 cell proliferation and differentiation were both improved by the addition of MWCNTs-COOH in scaffolds. Additionally, the proliferation and maturation of Schwann cells were enhanced on scaffolds containing MWCNTs-COOH. The neurite outgrowth of rat dorsal root ganglia (DRG) neurons was promoted on MWCNTs-COOH-containing scaffolds, and those cultured on p-PC8 scaffolds showed elongated neurites with a length up to 78.27 μm after 3 days culture. Our results suggested that plasma treated nanofibers under appropriate conditions were able to improve cell attachment. They also demonstrated that plasma treated scaffolds containing MWCNTs-COOH, especially the p-PC8 nanofibrous scaffold could support the proliferation, differentiation, maturation and neurite extension of PC12 cells, Schwann cells and DRG neurons. Therefore, p-PC8 could be a potential candidate for peripheral nerve regeneration application.