Silver nanoparticles Iron nanoparticles Platinum nanoparticles Nanotechnology portal v t e Spinning Carbon Nanotube Carbon nanotubes ( CNTs ) are allotropes of carbon with a cylindrical nanostructure . Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, [ 1 ] significantly larger than for any other material. These cylindrical