SERS, analytical method Applications

Since SERS and SERRS are substance specific, they are ideal for characterisation and identification of chromatographically separated compounds. SE(R)R is not, unfortunately, as generally applicable as MS or FUR, because the method requires silver sol adsorption, which is strongly analyte-dependent. SE(R)R should, moreover, be considered as a qualitative rather than a quantitative technique, because the absolute activity of the silver sol is batch dependent and the signal intensity within a TLC spot is inhomogeneously distributed. TLC-FTIR and TLC-RS are considered to be more generally applicable methods, but much less sensitive than TLC-FT-SERS FT-Raman offers p,m resolution levels, as compared to about 10p,m for FTIR. TLC-Raman has been reviewed [721],... 

To demonstrate the application of these butterfly wing SERS substrates to the problem of protein-binding detection, Garrett et al. devised a protein-binding assay. There are a variety of methods for binding proteins to a metal surface, some of which depend on the amino acid composition of the protein, others of which do not. Direct adsorption via covalent bonds between sulfur groups in proteins and metal surfaces has been used with some success [43] however, this method is unsuitable for use in Raman spectroscopy-based assays, as nonspecific binding may result in a wide variety of conformational orientations of the molecules with respect to the metal s surface. This can lead to Raman spectra that are difficult to reproduce. Not only that, but the analyte may bind to the metal as well as the antibody, which can lead to noisy spectra. 

Figure 1 Number of journal publications devoted to environmental applications of various Raman techniques as a function of years. The resurgence of normal Raman spectroscopy in the late 1990s due to the improvements in Raman instrumentation is obvious. Also, a recent increase in SERS applications can clearly be seen. Moreover, the maturity of Raman spectroscopy as an important analytical tool in the analysis of complex environmental mixtures is seen in the steady growth of hyphenated techniques involving Raman spectroscopy. Note that publications reporting the use of hyphenated techniques were included in the tally for both hyphenated techniques as well as the specific Raman method employed (i.e., NRS, RRS, and SERS). In addition, publications reporting the use of the SERRS technique were included in the tally for both RRS and SERS. Hence, the Total category is not always equal to the sum of the NRS, RRS, and SERS applications.

S.E.J. Bell, A. Stewart, Quantitative SERS methods, in Surface Enhanced Raman Spectroscopy Analytical, Biophysical and Life Science Applications, ed. by S. Schliicker (Wiley, Weinheim, 2011), pp. 71-86... 

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