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Surface enhanced resonance Raman scattering (SERRS) combines enhancement of the
Raman signal by surface enhancement with resonance enhancement from a chromophore
contained in the analyte We have shown in both DNA and antibody assays that
this method of detection can be more sensitive than fluorescence and that the
ability to identify and determine the concentration of several analytes in a
mixture is much superior.
The advantages have been used to develop reliable and quantitative analytical procedures for disease conditions such as Cystic Fibrosis, Chlamydia and Gonorrhoea (1,2). The methods use specially designed probes which have a chromophore and surface attachment group. These are used with colloidal suspensions of silver to create SERRS. The use of colloidal suspensions has enabled us to add the superior detection capability to standard solution based molecular biology protocols.
Figure 1 Shows two probes synthesised. In probe 1 a chromophore which does not adhere well to the negative surface is forced onto it by adding positively charged propargyl amine groups and in the second, a positively charged dye which adheres directly is used.
Figure 1 The use of colloidal aggregates to obtain sensitive and specific SERRS from specially designed probes
The quantitative response is illustrated in figure 2. In one study sensitive detection limits were obtained for 8 probes (3) and we have more.
Figure 2 Quantitative response of the SERRS intensity for the rhodamine probe illustrated in figure 1
So far 6 differently labelled probes have been discriminated quantitatively in one sample without separation and this number will increase. Figure 3 illustrates the potential to do this for a mixture of 3.
Figure 2 Discrimination of three differently labelled probes in a mixture without separation
The huge potential for multiple analyte analysis is being exploited in the development of assay procedures suitable for use in hospital clinics.
References
- Simple Multiplex Genotyping by Surface Enhanced Resonance Raman Scattering, SERRS Graham, D.*, Mallinder, B. J., Whitcombe, D., Watson, N. D., Smith, W. E.,Analytical Chemistry, 2002, 74, 5, 1069-1074.
- Evaluation of Surface Enhanced Resonance Raman Scattering (SERRS) For Highly Sensitive and Quantitative DNA Analysis Faulds, K., Smith, W. E., Graham, D. Analytical Chemistry, 2004, 76, 412-417.
- Quantitative simultaneous multianalyte detection of DNA by dual-wavelength surface-enhanced resonance Raman scattering Faulds K., McKenzie F., Smith W.E., Graham D., Angewandte Chemie, 2007, 46, 1829 -1831.
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