Quantitative analysis of mononucleotides by isotopic labeling surface-enhanced Raman scattering spectroscopy

A novel surface-enhanced Raman scattering (SERS) approach for accurate quantification of mononucleotides of deoxyribonucleic acid (DNA) is described. Reproducible SERS measurement was achieved by using isotopically labeled internal standard. By measuring the SERS spectra of mononucleotides and its isotope internal standard in combination with multivariate data analysis, the method was successfully applied to quantify mononucleotides. The independent validation of analyte concentrations gave a standard deviation of within 2%, which is comparable to HPLC result. Finally, a mixture of four mononucleotides of DNA was prepared to explore the possibility of quantifying the concentration of label-free, sequence-specific DNA strands by this approach. As compared to liquid chromatography/mass spectrometry (LC/MS), our method can be similarly precise but the SERS measurement is simple, rapid and potentially cheap.