Comparison of SE R RS and Fluorescence for Biological Studies

Sjostrom, C., and Harris, J.M. (2002) Journal of the American Chemical Society, 124, 2408. Copyright 2002 American Chemical Society. 

Compared to fluorescence, SERRS has some significant advantages. Unlike fluorescence-based methods, SERRS measurements are unaffected by quenching by oxygen or other species, are less sensitive to photobleaching, and are inherently 

For multiplex measurements, when compared to fluorescence, SERRS also offers significant advantages. In multiplex measurements fluorescence has the disadvantage that the electronic spectra produced are broad (typically 50 to lOOnm full width at half maximum) and therefore overlap so that the technique is limited to the simultaneous measurement of around four dye labels [69, 77]. In contrast, SERRS uses the vibrational Raman spectrum of the label as a spectroscopic molecular fingerprint As a result the information content of the spectra is much higher and, because the vibrational bands are much narrower (about 1 nm full width at half maximum), spectral overlap is much less of a problem. Thus using SERRS it is possible to readily identify the components of a mixture without extensive separation procedures [78] and it has been estimated in the literature that simultaneous measurement with up to 30 SE(R)RS labels should be possible [79]. 

SE(R)RS is well suited as a technique for the detection and discrimination of DNA due to its high sensitivity and advantages over fluorescence [63]. The first applications of SE(R)RS to DNA detection by Vo-Dinh s group used roughed silver surfaces to achieve surface enhancement [80-82] but this approach suffers from problems of reproducibility. Using silver colloids Faulds et al. have demonstrated the quantitative detection of dye-labeled ohgonucleotides by SERRS [83]. 

There are several examples of multiplexed SERRS measurements as apphed to DNA assays [69, 70, 73, 77, 84—89] reported in the literature and a few examples of immunoassays. Thus Woo et al. [90] described a triplex immunoassay for the detection of bronchioalveolar stem ceUs, Cui et al. [91] used two dye labels to carry out a duplex sandwich immunoassay, Jun et al. [92] reported a triplex immunoassay using SERS, and Lutz et al. [93] described a quadruplex platelet activity state plate binding assay. 

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