Cytocompatibility of carbon nanofibers for use as a neural biomaterial

Carbon nanofibers possess excellent conductivity properties, which may be beneficial in the design of more effective neural prostheses. The objective of the present in vitro study was to determine cytocompatibility properties of carbon nanofibers pertinent for neuronal prosthetic applications. Carbon fibers were compacted in a manual hydraulic press via a uniaxial loading cycle. The substrates were prepared from four different types of carbon fibers, two with nanoscale diameters and two with microscale diameters. In these two categories, both a high and a low surface energy fiber were investigated. Astrocytes (glial sear tissue-forming cells) were seeded onto the substrates for adhesion, proliferation, and long-term function studies. Astrocytes preferentially adhered, proliferated, and showed the greatest alkaline phosphatase activity on the carbon fiber that had the largest diameter and the lowest surface energy. For this reason, carbon fibers in the nanometer regime with high surface energies may limit astrocyte interactions. Positive interactions with neurons, and, at the same time, limited astrocyte functions leading to scar tissue formation are essential for increased neuronal implant efficacy.