With its ultrahigh sensitivity with selected molecules such as Rhodamine 6G, crystal violet, etc., surface enhanced Raman spectroscopy (SERS) has attracted tremendous attention for its potential in analytical and bioanalytical applications.  Up to date, however, reliable prediction of analyte concentration on the basis of the SERS signal intensity has not been possible due to a series of sample-, SERS substrate-, and Raman instrument- related issues.  Presented here is a novel ratiometric SERS method that uses an isotope substituted version of the analyte as the internal reference.  Because isotope-substitution has no detectable effect of the analyte adsorption onto the SERS substrates, concentration ratio of the analyte and its internal reference is strictly proportional to their concentration ratio, regardless of the variations in activity of the SERS substrate, the composition of the sample matrix, and instrument performance.  Two example applications of this isotope substituted ratiometric SERS method will be presented.  The first is the SERS-based comparative carbohydrate quantification that uses a pair of isotope-substituted Rhodamine B derivative as the SERS tags.  The second one is for quantitative ligand adsorption to determine the structure, binding affinity, and orientation of mercaptobenzimidazole on gold nanoparticles.

Quantitative surface enhanced Raman spectroscopy

244th National Meeting (2012)

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