Without the semiconductor nanocrystal quantum dots, the nanotubes are difficult to see, because they absorb rather than reflect light. Dr. Baskin, a neurosurgeon, and Vladimir Didenko, PhD, at the Methodist Neurological Institute in Houston, Texas, used an enzyme to create a permanent bond to attach the dots to the nanotubes. The light absorption properties of the nanotubes are bypassed by using the fluorescent dots.

It is hoped that this labelling technique will enable nanotubes and other nanoscale devices to be used for biomedical research, including the precise delivery of medication to specific cancer cells, effectively sparing surrounding healthy cells.

"By attaching these Q-dots like beads on a string, we have the potential to link tens, hundreds, thousands of these strings together, creating nanomachines that can act like probes, giving researchers a new view into cancer cells, proteins, and DNA molecules," said Dr. Baskin.

Once fluorescent, nanotubes can be observed by microscopes, which could enable the construction of nano-size devices such as probes for biomedical research.

In addition to this research, Baskin and Didenko have also worked with the late Dr. Richard Smalley, one of the Nobel laureates who developed and researched "buckyballs" of carbon, closely related to nanotubes. Baskin, Didenko, and Smalley created a way to tightly wrap a polymer material around a nanotube, like a spool of thread, allowing them to create nanotubes labels. This resulted in a fluorescent probe and made individual nanotubes observable by a fluorescent microscope (see, for example, Nano Letters; 2005, Vol. 5, No. 8).