Detection of DNA probes using Diels Alder cycloaddition and SERRS

A number of methods for detecting specific DNA sequences have been used to provide data for use in diagnosis of disease states and examination of gene expression. This study shows how the use of labelled oligonucleotides created by Diels Alder cycloaddition can be used as surface enhanced resonance Raman scattering (SERRS) active probes that provide easily identifiable signals at low concentrations in a mixture. The probes were produced by first tagging the oligonucleotides with a furan residue at the 5'-terminus to act as the diene. Three specifically designed benzotriazole azo maleimide dyes were then used as dienophiles to undergo cycloaddition with the furan modified oligonucleotide to generate SERRS active probes. These probes gave excellent SERRS signals from a silver-PVA film. Surface mapping of the silver PVA film indicated that the distribution of the dyes was uniform and that the number of moles of probe detected at any one time was approximately in the attomole region.