Nanotubes (NTs) are cylindrical hollow tubes similar in diameter to biological ion channels (a few nanometers). They can be fabricated from a range of materials, from the more commonly studied carbon to boron nitride (BN) and silicon carbide. In recent years there have been rapid advances in technologies for synthesizing NTs made from various materials and modifying their surface chemistry. An excellent summary of current techniques of fabricating NTs is given by Harris.