Detection of Molecular and Biomolecular Species by Surface-Enhanced Raman Scattering: Nanoengineered Substrates for SERS Detection

摘要

Our research has confirmed that the significant Raman enhancement from a nanoshell based substrate is generated by the electromagnetic enhancement of individual nanoshells, not aggregates (dimers, trimers, etc.). Unlike metal colloids and roughened surfaces, the significant Raman enhancements achieved are consistent across the substrate and are not related to 'hot spots' associated with aggregate geometries. This will allow the reproducible manufacture of a substrate with superior enhancement for use in future target specific SERS applications. The Raman enhancement achieved this individual nanoshell substrate equals or exceeds 10 exp 10, evaluated using direct comparison between the unenhanced and enhanced signal from the same molecule. It is important to note that when these enhancements are compared to those of Kneipp et a., who reported values of 10 exp 10, the nanoshell-based enhancement appears to be approximately 10 exp 15 using their analytical method. The enhancement factors demonstrated are consistent with reported enhancements factors necessary for single molecule detection. Nanoshell-based SERS substrates have been reproducibly manufactured and tested for stability under various conditions. The method of manufacturing will allow use with both dry and aqueous samples.