Fig. 2.

(a) AFM image of TAO nanotube taken by tapping mode in air. The B tile layers are visible as brighter stripes (because of increased height) oriented perpendicular to the long axis of the tube. (b) Very-high-resolution image of nanotube taken by tapping mode under buffer. Single helix holes between adjacent tiles are visible as darker patches in several layers. (c) TEM image of negative-stained sample, showing a section of nanotube that appears to have split into flat lattice. (d and e) Negative-stained TEM images of TAO nanotubes with gold nanoparticles attached to the ends, apparently by interaction with thiol sulfurs partially exposed at the tube termini.