what is the disulfide-bond analog for carbon nanotubes? unlike proteins, carbon nanotubes are rather regular. can they be doped in much the same way semiconductors are doped? could dopants be sites for disulfide-bond analogs to enable creation of nanotube bundles?
doping by replacing an occasional carbon with something else might be difficult; another possibility is to enclose atoms/molecules within the nanotube. can presence of ions inside be stable and affect things outside? or would ions simply repell each other and thus shoot out the ends of the nanotubes?