These are representative data showing the T_m effect of using different modifiers on the oligonucleotide precursors. By carefully selecting the modifiers (numbers in red) and the positions of the precursor on the oligo we can select the optimal primers to inhibit primer-dimer extension and non-specific PCR for sequencing reactions. In addition, the width of the melting transition was narrower in the case of all modified oligonucleotides, implying that they have a higher annealing specificity compared to unmodified (normal) oligos.