Engineers, geneticists and microscopists have used carbon nanotubes to measure the electrical conductivity of single DNA molecules.

Understanding the electronic properties of DNA has been a controversial issue for a number of years, partly because it is difficult to be sure that you are measuring the DNA itself and not, for example, effects due to the electrodes or the surface that is supporting the DNA. Achieving good contact between the DNA molecule and the electrodes is a major challenge, which is why Wonbong Choi, an engineer at Florida International University in the US, decided to use carbon nanotubes for the electrodes rather than a traditional metal. Choi wanted to measure the electrical conductance of single- and double-stranded DNA, so he recruited experts in atomic force microscopy from POSTECH in Korea and geneticists from the National Institute of Genetics in Japan to work on the project.

The team suspended a single DNA molecule across a tiny trench and bonded each end to a single-walled carbon nanotube electrode that was deposited on a silicon wafer. Because the diameter of a nanotube (∼2 nm) is similar to that of a DNA molecule, it was possible to measure electrical signals passing through the DNA molecule more accurately than in previous experiments with much larger metal electrodes. Choi hopes that such a measuring platform will lead to a better understanding of the properties of DNA and therefore help in developing techniques for reversing DNA damage caused, for example, by mutations (Nano Lett. 8, 26–30; 2008).

Choi and his collaborators already knew each other, which helped them to overcome the cultural barriers between the US, Korea and Japan. “Communicating with a person who is in different research area and sending samples to foreign countries were the most difficult parts,” Choi recalls, “but the rewarding part was that we could reach our goal in the shortest time. We also learned a lot from working in a multidisciplinary collaboration. The meaning of collaboration is 'give and take'.”