Biological applications of optical tags based on surface-enhanced Raman scattering

Detection tags are needed in biological assays to identify specific products or events from among the thousands of molecules and events present in a cell or biological extract. Although there are measurement techniques that can directly detect a wide variety of native molecules (including mass spectrometry and nuclear magnetic resonance [NMR]), in complex biological systems, it is often useful to tag a specific molecule of interest to make it “visible” to a detection system. Optical tagging techniques are often favored because they can be applied to virtually any measurement format, from microarrays to cellular assays to in vivo applications.