Chronic neural biomaterials (usually composed of silicon) are frequently surrounded by scar tissue formation immediately after implantation, which clearly interferes with their functionality. It is believed that such traditional silicon materials induce a large gliotic response due to surface roughness values that may be rough at the micron-scale in some cases, but are smooth at the nanoscale; whereas neural tissue possesses a large degree of nanometer surface roughness due to the presence of numerous nanostructured proteins like laminin. The present study investigated two novel nanostructured materials: carbon nanofibers and nanostructured silicon. Carbon nanofibers were combined with polycarbonate urethane in varying weight percentages. Porous silicon was prepared by chemical etching treatments resulting in mesoscale pores with nanoscale roughness in between the pores. Results showed astrocytes preferentially adhered to the carbon nanofiber composites and silicon substrates with the greatest amount of micron scale porosity. In contrast, increased nanoscale surface roughness (the silicon with the least porosity (and hence the greatest nanoscale roughness) as well as the smallest dimensioned carbon nanofibers) reduced astrocyte adhesion. The nanoscale surface roughness of the composites reduced astrocyte adhesion unless micron scale pores were present. These results collectively indicate that materials without micron scale pores and with a large degree of nanoscale roughness may limit astrocyte adhesion which is needed for the design of the next generation of more successful neural prosthetics.