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Peripheral nerve injuries can lead to lifetime loss of function and permanent disfigurement. Different methods, such as conventional allograft procedures and use of biologic tubes present problems when used for damaged peripheral nerve reconstruction. Designed scaffolds comprised of natural and synthetic materials are now widely used in the reconstruction of damaged tissues. Utilization of absorbable and nonabsorbable synthetic and natural polymers with unique characteristics can be an appropriate solution to repair damaged nerve tissues. Polymeric nanofibrous scaffolds with properties similar to neural structures can be more effective in the reconstruction process. Better cell adhesion and migration, more guiding of axons, and structural features, such as porosity, provide a clearer role for nanofibers in the restoration of neural tissues. In this paper, basic concepts of peripheral nerve injury, types of artificial and natural guides, and methods to improve the performance of tubes, such as orientation, nanotechnology applications for nerve reconstruction, fibers and nanofibers, electrospinning methods, and their application in peripheral nerve reconstruction are reviewed.

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Poly-N-isopropylacrylamide was successfully grafted onto a polystyrene cell culture dish and γ-preirradiated in air. In this study, the effect of a γ-pre-irradiation dose of radiation (radiation absorbed dosages of 10, 20, 30, 40 KGy) under appropriate temperature and grafting conditions was investigated. The Fourier transform infrared spectroscopy analysis showed the existence of the graft poly-N-isopropylacrylamide (PNIPAAm) on the substrate. The optimal value of the dose for grafting was 40 KGy at 50°C. The scanning electron microscopy and atomic force microscopy (AFM) images clearly showed that increasing the absorbed dose of radiation would increase the amount of grafting. Surface topography and graft thickness in AFM images of the radiated samples showed that the PNIPAAm at the absorbed dose of radiation was properly grafted. The thickness of these grafts was about 50–100 nm. The drop water contact angles of the best grafted sample at 37°C and 10°C were 55.3 ± 1.2° and 61.2 ± 0.9° respectively, which showed the hydrophilicity and hydrophobicity of the grafted surfaces. Differential scanning calorimetry analysis also revealed the low critical solution temperature of the grafted sample to be 32°C. Thermoresponsive polymers were grafted to dishes covalently which allowed fibroblast cells to attach and proliferate at 37°C; the cells also detached spontaneously without using enzymes when the temperature dropped below 32°C. This characteristic proves that this type of grafted material has potential as a biomaterial for cell sheet engineering.