Carbon Nanotube String PlatformStudies have shown that the surface nanotopography of carbon nanotubes (CNTs) mimics that of the extracellular matrix, ECM, which has properties that provide structural and biochemical support to cells. CNTs have been shown to be able to promote differentiation; however, they can also provide neuronal guidance, influence neuronal growth at the morphological level, and alter the electrophysiology and behavior of neural stem cells through their surface morphology and electrical stimulation made possible by their intrinsic conductivity. Huang et al. investigated the efficacy of using a carbon nanotube (CNT) string substrate as a platform for electrical stimulation of neural stem cells in culture medium. Observations were made on the response of neural stem cells after electrical stimulation on morphology, gene and protein expression. The biocompatibility of the CNT rope substrate with cells was also analyzed. The ECM-like topography and electrical conductivity for electrical stimulation capabilities allow this CNT platform to be useful in promoting NSCs into mature neurons. Electrical stimulation may be important in the differentiation and maturation of neural stem cells because it has been shown that there is an endogenous electrical field, in vivo, that can serve as a guiding cue for the migration and differentiation of neural cells. CNTs are uniquely organized and have a specific structure that helps promote the controlled differentiation of neural stem cells. The CNTs are wrapped in bundles of approximately 20 nm in diameter; Each bundle is composed of individual nanotubes of approximately 1-2 nm (the typical width of single-walled CNTs). CNT topography was… half of the paper… 2), another neuron-specific marker involved in microtubule assembly in later stages of neuronal development. B-tubulin and MAP2 were chosen as maturity markers to distinguish NSC maturity, while nestin is used as an immaturity marker. After 1 week of culture, NSCs stained for nestin and B-tubilin tended to express more nestin, indicating that most NSCs are in a premature state. After 2 weeks, nestin expression was downregulated compared to B-tubulin, especially in the electrically stimulated group, indicating that NSCs matured after 3 weeks. There also tended to be greater neurite extension and elongation in the electrically stimulated group. When Nestin and MAP2 are stained simultaneously, MAP2 tended not to be expressed very highly during week 1, however, it appeared to be expressed more highly in electrically stimulated subjects. cells.