US Patent 7195780 - Nanotube with particle cap

http://www.freepatentsonline.com/7195780.html

This patent teaches a nanotube (silica or polymer rather than carbon) with a nanoparticle "cap" for delivering bio-active agents. Claim 1 reads:

1. A nanotube comprising: (a) a hollow tubular body defining an inner void, comprising a first end and a second end, wherein the first end is open; and (b) a first end cap positioned over the first open end, wherein the end cap is attached to the hollow tubular body by a covalent bond and the capped nanotube has a maximum dimension of less than 100 microns.