Designing nanostructures with optimized surface-enhanced Raman scattering behavior

Investigations in the burgeoning field of nanophotonics have demonstrated that certain nanostructures act in previously unanticipated ways. One such behavior is surface-enhanced Raman scattering (SERS), an area of substantial interest, as demonstrated by the hundreds of scientific papers published on the subject during the past 5 years. SERS was discovered over 3 decades ago.1–3 It transforms the basic Raman technique (a measure of the structure and properties of molecules based on their interaction with light that normally has very weak intensity relative to other spectroscopies) into one that has highly sensitive detection capabilities. Whereas Raman scattering is useful for analyzing the structure of small molecules and for addressing traditional analytical issues such as a material's composition in bulk, SERS promises advances in ultrasensitive detection of a variety of molecule classes. The most important among these are biomolecules such as DNA, RNA, and proteins. Such detection capabilities (which can approach single-molecule limits) could lead to very sensitive and even mobile medical diagnostic assays. Yet the SERS phenomenon is still perplexing to scientists.