Being particular about DNA

Surface-enhanced Raman spectra (SERS) of DNA and RNA mononucleotides can be detected with high sensitivity, according to UK researchers. Using citrate-reduced silver colloidal nanoparticles aggregated with magnesium sulfate instead of the more common halide ions, reduces inappropriate enhancements and produces spectra that are sufficiently different to allow each to be distinguished.

“The main advantage of our SERS approach is that it allows direct label-free identification of mononucleotides in aqueous solution,” Steven Bell, Director of the Innovative Molecular Materials Group, at Queen’s University Belfast, explains, “There is no requirement for labels because the Raman signals of each of the mononucleotides are intrinsically different due to the differences in their chemical structures.” He adds that spectra can be obtained at ten nanograms per millilitre. “We were working with large samples but reducing the sampling volume to a few microlitres would move the sample down to tens of picograms,” he says.


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