Polymerase chain reaction (PCR) is an invaluable diagnostic tool, but its complexity prohibits the development of a more precise and quick-to-use system. In August 30 Science, Yun Wei Charles Cao and colleagues from the Institute for Nanotechnology, Northwestern University, Evanston, IL, US describe a new method for detecting genetic material that doesn't rely on the polymerase chain reaction.

Cao et al. used gold nanoparticles of approximately 13 nanometers in diameter, which function as a surface-enhanced Raman scattering promoter for dye-labeled particles. The dye-labeled particles are captured by target molecules on a chip and send a signal after being scanned by a laser. Using six Raman-labeled nanoparticle probes, they could distinguish six dissimilar DNA targets, as well as two RNA targets with single nucleotide polymorphisms.

The current unoptimized detection limit of this method is 20 femtomolar. "By providing a near infinite number of signals, this advance allows researchers to quickly...

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