To detect cancer as early as possible, dozens of research groups are developing methods to detect trace levels of cancer-related proteins and genes in blood or other biological samples. The latest: carbon nanotubes can serve as highly sensitive optical labels for use in a wide variety of assay systems.

Researchers at Stanford University and the Center for Cancer Nanotechnology Excellence Focused on Therapeutic Response have developed a new type of coating for attaching any number of different types of targeting agents to the surface of single-walled carbon nanotubes. This coating, a branched form of the biocompatible polymer poly(ethylene glycol) (PEG), enabled the investigators to readily couple antibodies to carbon nanotubes. In the experiments reported in their current paper in Nature Biotechnology, the antibodies were designed to identify specific proteins immobilized on a standard protein array microchip.