Credit: © 2006 ACS

Surface-enhanced Raman spectroscopy (SERS) is a popular technique for analysing material surfaces and identifying chemical compounds. SERS relies on detecting Raman shifts in light scattered by molecules and, as its name suggests, the signal is enhanced when the molecules are close to a surface. However, problems in getting the molecules of interest close to a SERS-active surface, while excluding non-target compounds such as proteins, has stopped the technique being used to detect biomolecules in living systems. Now, researchers at Northwestern University in the US have overcome this problem by adding a self-assembled monolayer of hydrophobic and hydrophilic molecules to a standard SERS substrate to make a glucose detector.

The extra monolayer introduced by Richard Van Duyne and co-workers1 improved the SERS signal by localizing the glucose molecules to within a few nanometres of the substrate surface, while excluding non-target molecules. When implanted under the skin of rats, their device was just as accurate as standard glucometers, and could detect changes in glucose concentration over timescales as short as 30 seconds. Although further refinements are needed, this approach could lead to improved glucose sensors for diabetics.