Whether Carbon Nanotubes Are Capable, Promising, and Safe for Their Application in Nervous System Regeneration. Some Critical Remarks and Research Strategies

Carbon nanotubes are applied in or considered for different fields of medicine. Among them is the regeneration or rebuilding of nervous system components, which still lack substantial progress; this field is supported by carbon nanotubes to a great extent as the principal material. The limited research on this issue has involved PU/silk/MWCNTs, PCL/silk/MWCNTs, PCL/PGS/CNTs, chitin/CNTs, PGF/CNTs, CNTs/PGFs/PLDLA, MWCNTs/chitosan, MWCNTs/PPy, PLA/MWCNTs, PU/PAA/MWCNts, GelMA/SACNTs, and CNTs alone, which have been subjected to different surface modifications and applied in the form of solid materials or scaffolds that are degradable or nondegradable. So far, these attempts have shown that the use of surface-modified MWCNTs is a promising way to improve the functions of nervous systems as a whole, even though some drawbacks, such as the potential cytotoxicity or the weak adhesion of CNTs to other components, may appear and be eliminated by their proper functionalization. The present review presents an idea of a nonbiodegradable scaffold structure composed of a chosen conductive polymer that is able to create a scaffold structure, a selected nanocarbon form (with MWCNTs as the first candidate), and a corrosion-resistant metal as a conductor. Other substances are also considered for their ability to increase the mechanical strength and adhesion of CNTs and their biological and electrical properties. The novelty of this approach is in the simultaneous use of nanocarbon and conductive metallic fibers in a polymer scaffold structure.