Free radical-quenched SERS probes for detecting H2O2 and glucose.

For developing a free radical-quenched surface-enhanced Raman scattering (SERS) probe, starch, a linear molecule, was used as a protective layer to coat gold nanoshells (GNSs) as enhancement substrates and then, methylene blue (MB) was absorbed on the starch-coated GNSs as a free radical-responsive element. By detecting the change of the SERS intensity of MB on GNSs, the free radical-quenched SERS probes were used to detect H2O2, a less active reactive oxygen species (ROS), which was first converted to free radicals, a highly active ROS, to react with MB absorbed on GNSs to quench its SERS. The free radical-quenched SERS probe was also used to detect glucose in the presence of glucose oxidase which converted glucose to H2O2. The free radical-quenched SERS probe would be a versatile platform for detection of biochemical processes. The integration of optically changed molecules and optical enhancement of nanomaterials provided a way for advanced materials and analytical science.