Using Surface-Assisted Laser Desorption/Ionization Mass Spectrometry to Detect ss- and ds-Oligodeoxynucleotides

We applied surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) with HgTe nanostructures as the matrix for the detection of single- and double-stranded oligodeoxynucleotides (ss-ODNs and ds-ODNs). The concentrations of surfactant and additives (metal ions, an amine) and the pH and ionic strength of the sample matrix played significantly different roles in the detection of ss- and ds-ODNs with various sequences. In the presence of Brij 76 (1.5 %), Hg2+ (7.5 mu M), and cadaverine (10 mu M) at pH 5.0, this SALDI-MS approach allowed the simultaneous detection of T-15, T-20, T-33, and T-40, with limits of detection at the femtomole-to-picomole level and sample-to-sample intensity variation < 23 %. In the presence of Ag+ (1 mu M) and cadaverine (10 mu M) at pH 7.0, this technique allowed the detection of randomly sequenced ss- and ds-ODNs at concentrations down to the femtomole level. To the best of our knowledge, this paper is the first to report the detection of ss-ODNs (up to 50-mer) and ds-ODNs (up to 30 base pairs) through the combination of SALDI-MS with HgTe nanostructures as matrices. We demonstrated the practicality of this approach through analysis of a single nucleotide polymorphism that determines the fate of the valine residue in the beta-globin of sickle cell megaloblasts.