Chemistry and physics join the fight against infectious diseases.

Ralph Tripp, professor of infectious diseases at the University of Georgia in the USA, was looking for a way to detect viruses that was both rapid and sensitive to different strains of the same virus, but did not involve the use of antibodies or costly polymerase chain reaction assays. It was at a nanotechnology meeting organized by his university that he heard about surface-enhanced Raman spectroscopy (SERS), a popular technique for analysing surfaces and identifying chemical compounds, and met colleagues from the physics and chemistry departments. This multidisciplinary collaboration has now demonstrated the potential of SERS for detecting trace levels of viruses such as the respiratory virus that infects children, the elderly and people with compromised immune systems (Nano Lett. doi:10.1021/nl061666f; 2006).

The SERS approach involves illuminating a sample and detecting Raman shifts in the light that is scattered. If the sample is placed on a suitably nanostructured metal surface, the signal is enhanced by orders of magnitude, which improves the sensitivity of the technique.

In the Georgia collaboration, Tripp prepared samples of different viruses, Yiping Zhao fabricated the substrates from silver nanorods, and Richard Dluhy made the measurements. The SERS spectra revealed that each virus had its own 'molecular fingerprint'. Moreover, the different strains could be easily identified by comparing the shifts and relative intensities of the peaks in the spectra.

As a Georgia Research Alliance scholar, Tripp was able to get the project started with funds from his own laboratory, and his colleagues did the same. However, he admits that “it is often difficult to 'learn the language' of different sciences, particularly physics”. It is also important to be persistent and to be a good communicator, he adds. “I guess it is a lot like being a salesman.”